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Re: Wallet full of $100 bills
Quote:
Originally Posted by ddt0725
Usually very true but since John just purchased a couple very nice lenses, spending time enjoying them should make the wait less painful than purchasing the 35mm or 50mm now & having improved versions come out in September.
Denise
Here is the train of thought I had when I purchased my 35L a few months ago:
The likelihood of the 35L being replaced doesn't seem immanent to me. It is very sharp, it can easily keep up with the densely populated modern sensors. Nikon doesn't have a equivalent coming (that I know of).The 24L II was produced because it had lots of issues and just to be in the IQ ball park of the 35L.The 135L is 8 years older than the 35L and yet to be replaced. I would expect the 135L to be replaced long before the 35L since it could really reap the benefits of IS. Lastly, if the 35L was replaced. wouldn't I still be happy with the mark I at a substantial savings.
If you listen to rumor sights you will be afraid to buy anything unless it came out yesterday.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Keith B
The likelihood of the 35L being replaced doesn't seem immanent to me. The 135L is 8 years older than the 35L and yet to be replaced. I would expect the 135L to be replaced long before the 35L since it could really reap the benefits of IS.
I'm not so sure. I think Canon will do something at the 35mm focal length. Of course, that something might be an EF-S 35mm f/1.8 announced along side a 60D. But, given the way they've been marching through the shorter L primes with updates and new releases, I think an update to the 35L is a reasonable possibility.
Incidentally, the 135L (released in 1996) is only 2 years older than 35L (released in 1998). But, a 135L with IS would sure be a nice lens!
Quote:
Originally Posted by ddt0725
...since John just purchased a couple very nice lenses, spending time enjoying them should make the wait less painful...
This is true - I'm pretty well covered, and looking to fill some niches. A fast prime will be great for portraits (50/85, not so much 35), but my main use will likely be indoors in low light. Sure, I want it now...but the real need for a a low-light lens will start picking up in Fall when the days start getting shorter, not now when daylight is still streaming in the windows after 7pm - f/2.8 is ok there.
Quote:
Originally Posted by crosbyharbison
Unless your losing money or potentialclients...then there is noinherentreason to not wait forsomethingyou'd rather have.
Purely a hobby for me. If I decide that the 85L is the way to go, the end of the rebate will be a factor. If I decide on the 50L, there's no reason not to get it now. But if I decide on the 35L, I'll most likely wait until later in the summer.
Quote:
Originally Posted by bburns223
I know the 85L is awesome and all but it has a weird focus mechanism (yeah, I don't known the tech photo term) that makes it AF much slower that than non-Ls including the 85mm 1.8. the 50mm f/1.2 is weather sealed and doesn't have the crap AF of the 85L.
Electronic manual focus. Yeah, it's odd, but 'crap AF' seems a little harsh. [:P] AF is relatively slow, compared to the 85mm f/1.8, for example - but I bet the 85L focuses faster than most non-USM lenses. However, the relatively slow AF is not a result of the electronic MF, but rather due to the front focusing design and the fact that the front element on that lens is so large. I think the real annoyance of the electronic MF will be the need to remember to focus the lens to infinity (so the front element is fully retracted) prior to unmounting the lens, since it won't focus without power from the camera.
Quote:
Originally Posted by ddt0725
Getting back to your original questions and being the totally non-analytical person that I am, I think you should at least narrow your choices down to #3 & #5. First off, you know you are going to want the Mk II as soon as it hits the stores and your going to have one sore butt after kicking yourself so many times if you don't wait it out! As for #3, I LUST for this lens and it is on my never will be able get list! Well, maybe never!
Thanks, Denise! I agree about the MkII comment - intellectually, I know that if I get and like a lens, and a MkII comes out a few weeks later, it doesn't change the performance of the lens I'd have already bought, and I'd have saved some $. But, I do tend to prefer the latest and greatest, and it would bother me, a lot. That's just me.
No question, the 85L is a lust-worthy lens. I'm still working through the focal length issues, though.
So, I'd narrow it down to #2, #3, or #5 - 50L, 85L, or wait. If I get the 50L, I won't kick myself if they announce a 50mm f/1.4 MkII - I'll have an L lens. [:)]
From a focal length standpoint, the 50L is seeming like the best choice - wide enough for indoor shots of wife and daughter interacting, but long enough for reasonably tight portraits, too. 35mm is plenty wide enough, but I suspect too wide for portraits. 85mm is perfect for tight portraits, but a bit long for indoor family shots. I really need to try the experiment of shooting for an evening with each focal length!
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
Quote:
Originally Posted by Keith B
The likelihood of the 35L being replaced doesn't seem immanent to me. The 135L is 8 years older than the 35L and yet to be replaced. I would expect the 135L to be replaced long before the 35L since it could really reap the benefits of IS.
I'm not so sure. I think Canon will do
something at the 35mm focal length. Of course, that something might be an EF-S 35mm f/1.8 announced along side a 60D. But, given the way they've been marching through the shorter L primes with updates and new releases, I think an update to the 35L is a reasonable possibility.
Incidentally, the 135L (released in 1996) is only 2 years older than 35L (released in 1998). But, a 135L with IS would sure be a nice lens!
OOPS! For some reason I thought the 135L was from 1991.
Also, if you asked me to bet on Canon NOT replacing the 35L in the next year or so, I wouldn't. I just have a gut feeling it isn't on there priority list.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
Thanks again for the great discussion, Jon - feel free to 'pester' more tomorrow!!! [img]/emoticons/emotion-2.gif[/img]
Okay, here goes :)
Quote:
Originally Posted by neuroanatomist
how does a shot of an ISO 12233 chart with an 85mm f/1.2 @ f/1.2 using a FF body, being less sharp than a shot with a 135mm f/2 @ f2 using the same FF body, show anything about comparing crop sensor IQ with FF IQ.
All right, I'll tell you how.
I wasn't being clear at all, but my point was only: consider a hypothetical dude - perhaps a neruoanatomist, perhaps someone of a different profession, it hardly matters- who is considering the $1500 50mm f/1.2 to go on his 1.6x crop camera(which may or may not be a 7D). Sure, the 50 1.4 is cheaper, but he really wants that bit more speed and the slightly better IQ the f/1.2 gives beyond f/2.
I say, dude in question might instead consider getting an85 f/1.8 and a full frame camera (if said dude already has a 85 1.8, so much the better). On the full frame the 85 is pretty close to 50mm f/1.2 (slightly faster, even).
To compare the two options, compare an 50mm f/1.2 @ f/1.2 with an 85mm f/1.8 @ f/1.8 (don't compare the lenses at the same f number... f/1.8 on the ff camera acts like f/1.2 on the crop). Ideally, we would use ISO charts for the cameras in question, but we don't have that. Instead, compare them on full frame (thats all we have for those two lenses). To imagine what 50mm f/1.2 on the cropcamerais like, think of throwing away 60% of the full frame 50mm f/1.2 picture. 50mm f/1.2 starts out worse, and gets worse still when you throw most of it away.
Now 1) I realize you're throwing away the worst 60% and keeping the best. Still, though, I think cropping would make the image much worse than it already is. After all, few lenses get *better* when we add extenders, and that's pretty much what we're doing when we crop (modulo optical abberations of the extender itself, which I *guess* are secondary). 2) I realize that a 7D has far more resolution than what you would have if you cropped the full frame camera used to make the chart. But with these small f numbers and with these lenses, I think we're in a zone where our image is more lens-limited than megapixel-limited. 3) A 7Ddiffersfrom thecameraused to make the chart in other ways, including but not limited to a different OLPF. True.
So it isn't exactly right to say "throw away 60% of the 50 1.2 picture on the 1DsIII to see what 50 1.2 would look like on the 7D", but it is an approximation. I think (and you're free to disagree... if I don't convince, that's fine, I just want to be understood :) ) that it is clear that the cheaper 85mm f1.8 on a 5DII doesn't just do better than the expensive 50 f 1.2 on a 7D, it does far better. My point is only, why pay a large premium for a marginal increase on one lens when you can have a big increase on *all* your lenses?
I don't claim that there are no reasonable answers to this question and that no one should buy a 50 f/1.2 for a 7D. I just think it is a question people paying a large premium for a very fast lens on a 1.6x camrea should ask themselves.
Quote:
Originally Posted by neuroanatomist
But in other ways, IQ probably suffers a bit even with good lenses (since sharpness and light both often fall off as you move to the edges of the image circle projection, and distortion increases at the periphery, and 'corner' on a crop sensor is 'mid-frame' for the image circle of an EF lens.
Fair enough. But unlike lack of sharpness, both of these are correctable in postprocessing(not without compromise, I admit). And anyhow, both of these problems havebotheredme much less than I expected they would. If I was shooting a bunch of straight lines with my 24-105 @ 24mm, I would probably feel differently about that lens.
Quote:
Originally Posted by neuroanatomist
You would have been better served by pointing me to a
comparison of the 200mm f/2L IS on the 5DII vs. the 7D - that comparison shows a slightly better IQ with that fast lens on FF, but I wouldn't call it dramatically better. Had you pointed me to that comparison, I would have probably pointed you to a similar comparison,
the200mm f/2L IS on the 7D vs. the 1DIV, where the 7D has slightly better IQ
than the 1DIV, and then I'd have been patting myself on the back for getting slightly better IQ with a camera that costs $3400 less!!
First, you should compare the 200 @ f/3.2 on the 5DII to f/2 on the 7D. On most lenses this will make a *big* difference, but for the 200 f/2... well, that thing is a freak. Second, an essential component of my above argument was that at these large apertures, we are lens-limited, not megapixel-imited. If we're not lens limited, then the camera with more megapixels wins-- 7D in this case. Once again, I can only say that the 200 f/2 is a freak. If you decide to pick up a 200 f/2 for your 7D I will not only agree with your decision, but I'll move in next door to you [;)]
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
All right, I'll tell you how.
Sorry, still not buying it. [:O]
The effects of crop factor apply to apparent focal length (really, a change in the angle of view) and apparent depth of field (because of the need to change subject distance for equivalent framing). So, in that context, yes - a 50mm f/1.2 lens on a crop body behaves like an 85mm f/1.8 lens on FF, and an 85mm f/1.2 lens on a crop body behaves like a 135mm f/2 on FF. But again, these equivalencies apply to angle of view and the associated depth of field when maintaining subject framing. Let's take the 50/85mm example. Say this hypothetical dude shoots a full-body portrait shot at 85mm f/1.8 on FF, and takes the shot so the subject's body vertically fills the frame - we'll say he's 10 feet from the subject. There's a certain DoF associated with that aperture and subject distance. Now that dude sets down the FF camera and puts the 85mm f/1.8 lens on the 1.6x crop. To take 'the same shot' (i.e. so the subject'sverticallybody fills the frame), he has to move further from the subject, out to about 16 feet. He's taking the shot at f/1.8. But, because he's further away, the depth of field is deeper - equivalent to that of the f/2.9 on FF. However, if instead that dude didn't move, and used the 1.6x crop + 50mm f/1.2 to take a torso shot that filled the frame, the depth of field would be similar to the 85mm f/1.8 on FF. (If Daniel weren't otherwise occupied, he'd jump in here and correctly remind us that perspective and compression would be changed in that case, too). But, the effect of a crop factor on DoF is due to the need to change subject distance to maintain a framing that would otherwise be changed by the crop.
You can read more about that on the DOFMaster tutorial on dSLR DoF. Actually, he states it much more succinctly that I just did: "Digital SLR (DSLR) cameras use lenses designed for 35mm SLR cameras. The physical performance of a lens doesn't change when you mount it on a DSLR. And yet, we see more depth of field (DOF) in photographs taken with the DSLR. Why? Because we change the DOF with our feet; we move further away from the subject."
These changes in apparent aperture, as they affect DoF, are not real changes in aperture. When you state, "...f/1.8 on the ff camera acts like f/1.2 on the crop..." it's important to remember that we're talking about apparent DoF, not IQ. We all know there's an optical benefit with most lenses when you stop them down from their maximum aperture - heck, even the nifty-fifty is pretty darn sharp at f/8. But moving a lens from a crop body to a FF body (and changing position to maintain subject framing) is not stopping down a lens by a factor of 1.6x. There's no inherent gain in the optical resolution of a lens (which contributes to 'sharpness' in an image) when you move it from a crop to a FF body.
The other point here is that you're talking about effects of sensor size on depth of field.ISO 12233 charts measure sharpness, which is different than DoF.
Quote:
Originally Posted by Jon Ruyle
First, you should compare the 200 @ f/3.2 on the 5DII to f/2 on the 7D.
The saga continues. You should compare them at f/2. Or f/3.2. But with the same aperture on both bodies. Yes, Bryan had to change the position of the camera relative to the chart, so the chart filled the crop frame vs. the full frame. Yes, doing that changed the apparent depth of field. But we're looking at pictures of a flat chart - DoF is irrelevant. Stopping down changes the optical performance of the lens (ok, not much on this particular lens). Changing the sensor size does not alter the optical performance of the lens. Un-cropping a sensor ≠ stopping down a lens.
Quote:
Originally Posted by Jon Ruyle
To imagine what 50mm f/1.2 on the cropcamerais like, think of throwing away 60% of the full frame 50mm f/1.2 picture.
Yes, you're 'throwing away' a lot of the total light gathering ability of the lens with a crop sensor, relative to FF. Because of that, the FF sensor will have less noise than the crop sensor. I'll admit - since one reason I want a fast lens is for use in low light, a FF body is another way - arguably a better way - to accomplish that goal.
So, to the extent than noise reduction also reduces sharpness, the crop sensor will be less sharp. But, these are subtle differences, compared to the more obvious effects on angle of view and apparent DoF.
Quote:
Originally Posted by Jon Ruyle
it is clear that the cheaper 85mm f1.8 on a 5DII doesn't just do better than the expensive 50 f 1.2 on a 7D, it does far better.
It is clear that the angle of view and DoF for thecheaper 85mm f/1.8 on a 5DII are equivalent to the expensive 50 f/1.2 on a 7D, for the same subject framing. It is clear that anything shot on the 5DII with any lens will have less noise at higher ISOs than anything shot on the 7D with any lens.
It's also clear that you could take a shot with the 5DII, crop it to the size of the 7D's image, and have less noise, but also much lower resolution.
To reverse your argument that a cheap lens on FF is better than an expensive lens on 1.6x, I'd argue that the high pixel density of the 7D's sensor demands lenses with the best optical performance, else it's just wasted resolution. Put another way, spending more for a FF body means you have a camera with a sensor that's more forgiving and tolerant of poor lenses.[^o)]
EDIT:Thinking about this overnight,I guess the way I view it is that as I've said, I'm quite happy with my 7D body. At this point, I'd perfer to stick to that one body and meet my current needs with additional high-quality lenses. When I do add a FF camera to my kit, I'm quite prepared to say "WOW!" as I finally see what noise at ISO 1600 and the DoF and associated OOF blur of an f/1.2 lens canreallybe like. I'll be even happier if I can do that while keeping a great AF system.
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Re: Wallet full of $100 bills
<span style="font-size: 10pt; color: black; font-family: 'Arial','sans-serif';"]
Quote:
Originally Posted by neuroanatomist
Changing the sensor size does not alter the optical performance of the lens
<o:p></o:p>
<span style="font-size: 10pt; color: black; font-family: 'Arial','sans-serif';"]Once again, we NEED Daniel! I do believe that he has said in the past that it does...I think it has to do with the optical design and its performance relating to a specific "special frequency". I'll look for the quote.<o:p></o:p>
<span style="font-size: 10pt; color: black; font-family: 'Arial','sans-serif';"]EDIT:<o:p></o:p>
<span style="font-size: 10pt; color: black; font-family: 'Arial','sans-serif';"]Here we go:<o:p></o:p>
<span style="font-size: 10pt; color: black; font-family: 'Arial','sans-serif';"]
Quote:
Originally Posted by Daniel Browning
Quote:
Originally Posted by adam
I've read various assertations that switching from a 40D to a 5D is like upgrading all of your glass,
Correct. All EF lenses have MTF curves optimized for full frame, so there is higher contrast and sharpness for a given print size.
<span style="font-size: 10pt; color: black; font-family: 'Arial','sans-serif'; mso-themecolor: text1;"]<o:p></o:p>
This whole thread is a good read. Check it out here:
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Re: Wallet full of $100 bills
I will stand firmly by my statement as you quoted it. "Changing the sensor size does not alter the optical performance of the lens." That must absolutely be true. It cannot. The lens is the lens. A better or worse image may be acquired by the same lens, depending on which camera body it's mounted on. But, whatever the camera does with the light coming out of the back of the lens is independent of the lens itself. The lens is the lens.
Obviously, that's a bit of atautology. The lens doesn't produce a usable image all by itself - that requires a camera. Really, we're talking about the optical performance a system - and the sensor is an integral part of that system. Clearly, changing the sensor size affects the optical performance of that system.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
"Changing the sensor size does not alter the optical performance of the lens." That must absolutely be true
You've got me there! I posted in haste [:$]
Quote:
Originally Posted by neuroanatomist
Really, we're talking about the optical performance a system - and the sensor is an integral part of that system
Agree again. This is a much better way to describe what we're talking about.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Daniel Browning
If you upgrade to full frame...and you have to crop the sensor down to APS-C size anyway, then you've effectively thrown away all that sensor you paid for.
...and for me, that is the main reason I'm sticking with the 7D for the time being. I already find myself needing to crop my wildlife shots - and that's with 400mm ona 1.6x crop sensor.
When I'm ready for a second body, it will be FF for landscapes/portraits. At that point, I'll enjoy the 'whole set of new glass' that all of my L-series lenses will become.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
EDIT:Thinking about this overnight,I
guess the way I view it is that as I've said, I'm quite happy with my 7D
body. At this point, I'd perfer to stick to that one body and meet my
current needs with additional high-quality lenses. When I do add a FF
camera to my kit, I'm quite prepared to say "WOW!" as I finally see what
noise at ISO 1600 and the DoF and associated OOF blur of an f/1.2 lens
canreallybe like. I'll be even happier if I can do that while
keeping a great AF system.
I absolutely respect that and I
hope you don't think I'm still trying to persuade you to buy a 5DII. But I do still hope to make you understand that my suggested IQ comparison is valid, or else
have you convince me that I'm wrong (and in this latter case I'll be especially
grateful to you for correcting my worldview [:)]) In any case, if this is becoming too tedious, I won't blame you if you give up on me, but I'm still enjoying it :)
The first step is for us to agree on one fact.
Quote:
Originally Posted by neuroanatomist
Say this hypothetical dude shoots a full-body portrait shot at 85mm f/1.8 on FF, and takes the shot so the subject's body vertically fills the frame - we'll say he's 10 feet from the subject. There's a certain DoF associated with that aperture and subject distance. Now that dude sets down the FF camera and puts the 85mm f/1.8 lens on the 1.6x crop. To take 'the same shot' (i.e. so the subject'sverticallybody fills the frame), he has to move further from the subject, out to about 16 feet.
With respect, I *believe* you are mistaken here (and of course I admit that it could be me). The hypothetical dude would not move at all. He would stay 10 feet from the subject to maintain the same framing.
What we mean when we say "50 f/1.2 on a crop body is like 85 f/1.8 on ff" we mean same subject distance, same framing, same DOF.
Quote:
Originally Posted by neuroanatomist
However, if instead that dude didn't move, and used the 1.6x crop + 50mm f/1.2 to take a torso shot that filled the frame, the depth of field would be similar to the 85mm f/1.8 on FF. (If Daniel weren't otherwise occupied, he'd jump in here and correctly remind us that perspective and compression would be changed in that case, too). But, the effect of a crop factor on DoF is due to the need to change subject distance to maintain a framing that would otherwise be changed by the crop.
If the dude does not move, he'll not have a head and torso shot. He'll have the same framing as with full frame, and (I'd be shocked if Daniel wouldn't agree) same compression and perspective. There's even the same amount of light striking the CCD, so assuming same sensor sensitivity, same photon noise. Lens aberrations aside, IQ aside, he has the same picture.
(All this is true only to a very close approximation... with high magnification, the effective crop factor changes from 1.6x, but for a full body shot, we may as well say it is exactly 1.6)
Do you not agree? I mean, if you have to move to get the same shot, then in what sense is it true that "50mm on 1.6fovcf is effectively 80mm on ff"
Quote:
Originally Posted by neuroanatomist
Un-cropping a sensor ≠ stopping down a lens.
I never meant to say that it was. The 200mm example is a bad one because we're getting different effective focal lengths when we use the same lens with different sized CCD's.
Okay, one more thing:
Quote:
Originally Posted by neuroanatomist
Put another way, spending more for a FF body means you have a camera with a sensor that's more forgiving and tolerant of poor lenses.[img]/emoticons/emotion-40.gif[/img]
This is, in a way, exactly my point. FF is more forgiving and tolerant of lenses. Isn't that a good thing? With ff, you get better IQ with an inferior lens. That's one reason I like it.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Mark Elberson
Once again, we NEED Daniel!
Ah, there you are, Mark. I was thinking that what we needed was you :)
Don't you agree that at much larger than macro distances, 50mm @ f/1.2 is equivalent in terms of framing at a given subject distance, compression angle, etc to 85mm @ f/1.8? (Not exactly, because 50 * 1.6 is 80, not 85, and 1.2 * 1.6 is not exactly 1.8, but never mind these small differences).
And if you agree with that, don't you agree that to compare the IQ of these systems (modulo differences inherent in the specific cameras such as pixel density, OLPF, etc etc) it is valid to compare 50 @ f1.2 taken on full frame with the outer 60% of the picture thrown away (because that's what you get when you take a picture with the crop camera) to 85mm @ 1.8?
And yes, I know, it would be better to just take a picture with 50 @ f/1.2 with the 7D and compare it to 85mm f/1.8 on the 5DII, but we don't have that 'cause Bryan didn't take pictures with the 50 @ f/1.2 and the 7D.
That's all I'm sayin'. I'm not telling anyone what they should or should not buy [:)]
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
The first step is for us to agree on one fact.
Quote:
Originally Posted by neuroanatomist
Say this hypothetical dude shoots a full-body portrait shot at 85mm f/1.8 on FF, and takes the shot so the subject's body vertically fills the frame - we'll say he's 10 feet from the subject. There's a certain DoF associated with that aperture and subject distance. Now that dude sets down the FF camera and puts the 85mm f/1.8 lens on the 1.6x crop. To take 'the same shot' (i.e. so the subject'sverticallybody fills the frame), he has to move further from the subject, out to about 16 feet.
With respect, I *believe* you are mistaken here (and of course I admit that it could be me). The hypothetical dude would not move at all. He would stay 10 feet from the subject to maintain the same framing.
Here, I think you're wrong. 85mm f/1.8 on FF - put that 85mm on a 1.6x crop, I hope we can agree that you now have the equivalent of 136mm f/2.9. We changed the camera, not the lens. To maintain the same subject framing now that 'the dude' has the equivalent of a 136mm lens, he'd have to move back. Put another way, you've got a 5DII with a 70-200mm zoom. Frame a shot at 85mm. Now, zoom your lens to 135mm (which is what the 1.6x crop factor does to the angle of view). You have step backward (to 1.6x the original subject distance) to maintain the same framing, right? When you do move further from the subject to maintain framing, if you leave your aperture setting the same, your DoF will get deeper. Those are the effects of cropping we're talking about - longer effective focal length, and narrower effective aperture because the distance changed to keep framing the same.
I remember a discussion with Daniel on the noise/compression/perspective issue, and I brought up subject framing - his response was that in the example photos he posted, he changed the focal length (using 70-200mm zoom lens) to 'simulate' the cropping effect. Here's a relevant quote, it's from this post:
Quote:
Originally Posted by Daniel Browning
If you wanted to see what happens when you change just subject distance and not focal length, here's what you would compare:
* 5D2 70mm f/6.4 at 10 ft
* 7D 70mm f/4 at 16 ft
That results in the same subject framing ("field of view"), but not the same angle of view and not the same perspective.
So, his example is essentially the same as mine - to get the same subject framing with the same lens on a crop body, compared to FF, you'd need to move further back, and that would result in the deeper DoF. You mentioned that, "The 200mm example is a bad one because we're getting different effective focal lengths when we use the same lens with different sized CCD's." When you compare different sensor sizes with the same lens, you're always going to get different effective focal lengths. Keep in mind, the sensor is not affecting the iris diaphragm diameter of the lens. A 100mm lens at f/2 is going to have a 50mm diameter iris diaphragm, regardless of what camera the lens is mounted on. The effects of decreasing sensor size on DoF are due to the fact that with the same focal length, you've got to move further away from the subject to get the same framing.
Here's a second excerpt from that same thread with Daniel:
Quote:
Originally Posted by neuroanatomist
In other words, as Bryan
states, "...as a generalization, using a higher FOVCF DSLR will yield more DOF in your similarly cropped pictures because you will be farther from the subject."
Quote:
Originally Posted by Daniel Browning
That's correct. The same focal length and f-number combined with further distance results in deeper DOF for smaller sensors.
So, that would seem to be the first fact to agree on, yes?
Quote:
Originally Posted by Jon Ruyle
Quote:
Originally Posted by neuroanatomist
However, if instead that dude didn't move, and used the 1.6x crop + 50mm f/1.2 to take a torso shot that filled the frame, the depth of field would be similar to the 85mm f/1.8 on FF.
If the dude does not move, he'll not have a head and torso shot. He'll have the same framing as with full frame, and (I'd be shocked if Daniel wouldn't agree) same compression and perspective. There's even the same amount of light striking the CCD, so assuming same sensor sensitivity, same photon noise. Lens aberrations aside, IQ aside, he has the same picture.
You're right, I'm wrong here (I actually edited the first example after I wrote it, but neglected to make this one match - that's what I get for posting before heading home from work). By changing both the lens (the actual focal length goes from 85mm to 50mm) and the body (1.6x crop brings the equivalent focal length back up to 80mm (close enough to 85mm for me), you'd get the same framing. To get the head/torso shot, our friend 'the dude' would have to move forward. The point I was trying to make is that if he took that head/shoulder shot (by moving forward), he'd get a thinner DoF than the body shot. But yes, it would be even thinner if he shot the head/torso shot with FF
Quote:
Originally Posted by Jon Ruyle
I'm still enjoying it
Me, too! Your turn...
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
Don't you agree that at much larger than macro distances, 50mm @ f/1.2 is equivalent in terms of framing at a given subject distance, compression angle, etc to 85mm @ f/1.8? (Not exactly, because 50 * 1.6 is 80, not 85, and 1.2 * 1.6 is not exactly 1.8, but never mind these small differences).
And if you agree with that, don't you agree that to compare the IQ of these systems (modulo differences inherent in the specific cameras such as pixel density, OLPF, etc etc) it is valid to compare 50 @ f1.2 taken on full frame with the outer 60% of the picture thrown away (because that's what you get when you take a picture with the crop camera) to 85mm @ 1.8?
And yes, I know, it would be better to just take a picture with 50 @ f/1.2 with the 7D and compare it to 85mm f/1.8 on the 5DII, but we don't have that 'cause Bryan didn't take pictures with the 50 @ f/1.2 and the 7D.
That's all I'm sayin'. I'm not telling anyone what they should or should not buy [img]/emoticons/emotion-1.gif[/img]
I thought the way you explained it first, although at first sounded backwards, was dead on. To evaluate the lenses based on one camera.
The 85 1.2 @ 1.2 on a crop acts like a 135 2.0 (136 1.92) but you can clearly see as great as 85 1.2 is, it is a huge trade off to use it wide open on a crop rather than the 135 2.0 on a FF.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Keith B
I thought the way you explained it first, although at first sounded backwards, was dead on. To evaluate the lenses based on one camera.
Not if your goal is to evaluate the cameras. Nor if you're goal is to evaluate the lenses as they would perform on different cameras. That's because lenses generally perform better when stopped down, so 'simulating' the effect of a crop sensor on DoF by stopping down on an ISO 12233 chart isn't valid. But, it's fine to compare just lenses, e.g. if the 85mm f/1.8 is sharper than the 50mm f/1.4 on a 1DsIII, it's reasonable to surmise that the85mm f/1.8 will sharper than the 50mm f/1.4 on a Rebel XSi, as well, even though Bryan didn't test either lens on that body.
Quote:
Originally Posted by Jon Ruyle
to compare the IQ of these systems ... it is valid to compare 50 @ f1.2 taken on full frame with the outer 60% of the picture thrown away (because that's what you get when you take a picture with the crop camera) to 85mm @ 1.8?
I'm interested in Mark's response to this. Personally, I don't think it's valid to compare two different lenses like that and assume those differences would hold up or be representative a of crop vs. FF comparison. We're talking about systems here - camera and lens, two variables. If you want to make a comparison, you have to make one of the variables a constant. To compare lenses, you use the same camera. That's why Bryan has shots of pretty much every lens with a 1DsIII - most people want lens comparisons. To compare cameras/sensors, you use the same lens, and vary the camera. Read Bryan's article about the test charts - "Lenses should be critically compared to each other only with test samples from the same camera body as it is the combination that is tested. Camera can be critically compared to each other using the same lens (theCanon EF 200mm f/2 L IS USM LensandCanon EF 200mm f/2.8 L II USM Lenshave results from many cameras included)..." That's why my FF vs. crop sharpness comparison used the EF 200mm f/2L IS USM lens.
Here's an example of why I don't think you can compare two different lenses on the same body, but crop one of them to simulate comparing sensors. Take the following, both using the same FF camera - 85mm @ f/4 with the outer 60% cropped away(to simulate the crop sensor), should be compared to uncropped 135mm @ f/6.4, right? By that logic, you could compare an image taken with an 85mm f/1.2L II @ f/4 on FF with the outer 60% of the image thrown away with a complete FF image taken with an EF 28-200mm f/3.5-5.6 @ 135mm f/6.3. Here's the comparison. Wow - that 'crop-simulating' 85L is making the crop sensor look way better than the FF.
Wait, I like that logic - FF IQ is just horrible, I'll stick with that nice sharp (simulated) crop sensor. [6]
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
Here, I think you're wrong.
Yes, of course I was :) I misread your post, and I apologize. I thought we were comparing the 50mm f/1.2 to the 85mm f/1.8. But if the dude is using the same lens with two different sized sensors, then of course he has to move to get the same full body picture, and of course the pictures will be different pictures (even if they're both full body)
Quote:
Originally Posted by neuroanatomist
The point I was trying to make is that if he took that head/shoulder shot (by moving forward), he'd get a thinner DoF than the body shot.
True.
Quote:
Originally Posted by neuroanatomist
But yes, it would be even thinner if he shot the head/torso shot with FF
Yes, if he shot it with the same actual f/ number.
But none of this bears on the point I am trying to make (and not doing a very good job). What I am saying is, first: 50mm @ f/1.2 on 1.6 crop is equivelant to 85mm @ f/1.8 on full frame (or very close) in pretty much all ways except image quality (at non-macroish distances). So if you have a 50mm f/1.2 on your 7D and I have an 85mm f/1.8 on my 5DII, we can take the same pictures with the same working distance. I think we agree on this part.
The second part of what I'm saying is: because I'm getting the same picture at 85mm f/1.8 @ f/1.8 as you are with the 7D + 50 f/1.2 @ f/1.2, then to compare IQ, it makes sense to compare 50 @ f/1.2 with 85 @ f/1.8. This is where you disagree with me, if I understand correctly. But... why would you want to compare the two lenses at the same f/number? At the same f/number, we're getting different DOF's, different noise, etc. Shouldn't we compare IQ in a situation where the *picture* is otherwise the same?
The third part of my point is that, while we would like to just take a picture of a chart with the 7D + 50 f/1.2 @ f/1.2 and compare to 5DII + 85 f/1.8 @ f/1.8, we don't have a picture of the chart taken with the 7D. So instead of 7D + 50 @ 1.2 we use 5DII + 50 @ 1.2, and throw away the outer 60% of the image. This is an approximation. The 7D has higher pixel density, and there are other differences, but I believe it is a pretty good approximation.
Finally, it seems to me that the 85 @ f/1.8 picture would be far better than the cropped 50 f/1.2, but if you disagree on this last, I won't argue.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
first: So if you have a 50mm f/1.2 on your 7D and I have an 85mm f/1.8 on my 5DII, we can take the same pictures with the same working distance. I think we agree on this part.
Absitively posolutely. [8-|]
Quote:
Originally Posted by Jon Ruyle
because I'm getting the same picture at 85mm f/1.8 @ f/1.8 as you are with the 7D + 50 f/1.2 @ f/1.2, then to compare IQ, it makes sense to compare 50 @ f/1.2 with 85 @ f/1.8. This is where you disagree with me, if I understand correctly. But... why would you want to compare the two lenses at the same f/number? At the same f/number, we're getting different DOF's, different noise, etc.
Correct - because we cannot compare50 @ f/1.2 with 85 @ f/1.8 with the same lens. I'd want to compare images of a test chart using the same lens, because different lenses have different optical characteristics and performance. I'd want to use the same aperture, because the selected aperture affects optical performance of the lens, and for a test chart, I don't care about DoF since the subject is a flat chart parallel to the sensor - if it's well-focused, DoF is irrelevant (when you see sharpness on Bryan's charts change with aperture, that's not DoF, that's the effect of the changing aperture on the optical properties of the lens - at the wide end, stopping down helps most lenses; the sensor only comes into play when diffraction starts setting in). You could use a zoom lens on the charts, so you can vary focal length and aperture in the same lens. Even doing this simulation with most zoom lenses isn't ideal, since their optical performance changes through the zoom range. But, trying it with the 70-200 II (a very good zoom lens, as we know), there's really not much difference going from 70mm f/3.2 to 135mm f/5.6, or from 135mm f/3.2 to 200mm f/5.6 (the closest I could get to a 1.6x factor).
So, I think there's no real way to "compare the IQ in asituation where the picture is otherwise the same."
*sigh*
Quote:
Originally Posted by Jon Ruyle
The third part of my point is that, while we would like to just take a picture of a chart with the 7D + 50 f/1.2 @ f/1.2 and compare to 5DII + 85 f/1.8 @ f/1.8
Exactly. But, we've established that those two pictures would have (essentially) the same framing and DoF. It's also apparent that for these specific lenses (which we can compare, since they are both tested with a 1DsIII), the85 f/1.8 @ f/1.8 is sharper than the50 f/1.2 @ f/1.2 (not surprising, I suppose, sinceoptically-speakingthe 85/1.8 is really a great value, and the 50L is optimized for bokeh over sharpness). Added to the reduced noise of a FF sensor vs. an 18 megapixel crop, it's obvious that overall IQ will be better with the85 f/1.8 on a 5DII than the50 f/1.2 on the 7D. So, do I agree with your final point, too.
All of this really just reinforces my sentiment that I'll eventually want a crop body with the shooting performance of the 7D for wildlife and action, and a FF body with the IQ of the 5DII for portraits and landscapes.
Your point that I may be better off getting a 5DII (instead of an ultrafast prime for use on a crop body) is valid, especially for one of the reasons that's been only a minor part of these discussions - significantly better noise performance.
Quote:
Originally Posted by Jon Ruyle
Consider the 5DII, dude. It would be like getting a whole new set of fast lenses.
I am definitely considering it.
The only problem I see with that is exemplified by a story I read (for the umteenth time) to my daughter last night - "If You Give a Mouse a Cookie," ... as in, if you give John a 5DII, he's going to want an 85L to go with it...
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
The only problem I see with that is exemplified by a story I read (for the umteenth time) to my daughter last night - "If You Give a Mouse a Cookie," ... as in, if you give John a 5DII, he's going to want an 85L to go with it...
**sigh** After all that, we're back to what I said to begin with ...you should get the 85L! [I] [:P]
I guess sometimes it just takes a non-analytical mind to spot the obvious! [:D]
Denise
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
The only problem I see with that is exemplified by a story I read (for the umteenth time) to my daughter last night - "If You Give a Mouse a Cookie," ... as in, if you give Keith a 5DII, he's going to want an 85L to go with it...
Huh? What?
The best way for me to describe the 85 1.2, is like being addicted to heroine without ever trying it. You don't know why, your body just needs it.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
Take the following, both using the same
FF camera - 85mm @ f/4 with the outer 60% cropped away(to simulate the
crop sensor), should be compared to uncropped 135mm @ f/6.4,
right?
Yes! (Though we're now in a much higher IQ zone- closer to being pixel limited. In this case, throwing away all those pixels is unfair to the 7D. I still think the 135 will do better, though.)
Quote:
Originally Posted by neuroanatomist
By that logic, you could compare an
image taken with an 85mm f/1.2L II @ f/4 on FF with the outer 60% of the
image thrown away with a complete FF image taken with an EF 28-200mm
f/3.5-5.6 @ 135mm f/6.3. Here's
the comparison. Wow - that 'crop-simulating' 85L
is making the crop sensor look way better than the FF.
Of
course I don't mean any lens in the world will do better on FF than any
effectively equivalent lens on a crop body. :) Even here, though,
after cropping, the difference might not be as great as you think. (I
dunno). Anyhow, making a non-stellar 7x zoom improve beyond a legendary
prime might be a little much to ask, but I think that often, cheap primes on FF will
far outperform expensive primes on crop.
Here's the thing. If you want a faster shorter lens, you can buy it. It will be expensive and the IQ will be worse than your longer slower lens. Or you can go FF and *all* your lenses will act like more expensive faster shorter lenses, only the IQ will get *better* rather than worse. (In some situations you'll like the longer slower version of the lens better, so I suggest you don't throw your 7D away [:)])
Quote:
Originally Posted by neuroanatomist
So, I think there's no real way to "compare the IQ in asituation where the picture is otherwise the same."
True. But what I've been doing is comparing a cheap lens on the 5DII to an expensive lens on the 7D, and trying to convince you that the cheap lens comes out way ahead. I gave the example of the 85 f/1.8 compared to the 50 f/1.2 and the 135 f/2 compared to the 85 f/1.2, but in general, lenses get faster and IQ gets better when you go to FF.
Quote:
Originally Posted by neuroanatomist
The only problem I see with that is exemplified by a story I read (for the umteenth time) to my daughter last night - "If You Give a Mouse a Cookie," ... as in, if you give John a 5DII, he's going to want an 85L to go with it...
Oooh, my daughter loves that one, too.
I say if John wants an 85L he should get one. The only problem I see is, if you give John an 85L, he's going to want a 5DII to go with it...
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Keith B
I thought the way you explained it first, although at first sounded backwards, was dead on. To evaluate the lenses based on one camera.
The 85 1.2 @ 1.2 on a crop acts like a 135 2.0 (136 1.92) but you can clearly see as great as 85 1.2 is, it is a huge trade off to use it wide open on a crop rather than the 135 2.0 on a FF.
Ah, good. I was starting to think I was going crazy :)
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
Quote:
Originally Posted by Keith B
I thought the way you explained it first, although at first sounded backwards, was dead on. To evaluate the lenses based on one camera.
The 85 1.2 @ 1.2 on a crop acts like a 135 2.0 (136 1.92) but you can clearly see as great as 85 1.2 is, it is a huge trade off to use it wide open on a crop rather than the 135 2.0 on a FF.
Ah, good. I was starting to think I was going crazy :)
The only thing I think you could test to SEE what the differences between 5DII and 7D would be, set a tripod up, shoot ISO chart with both bodies with the same lens. Not moving the distance and then examine the frames obviously they won't be the same perspective but I don't thin we are talking about that.
Pardon me if I'm off course, this is a hefty post and I have a short attention span.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Keith B
The only thing I think you could test to SEE what the differences between 5DII and 7D would be, set a tripod up, shoot ISO chart with both bodies with the same lens.
Keith, is that an offer to perform such a test? [A] You seem to have the necessary components (85L, 5DII, and 7D)...
Actually, photozone.de's Imatest results (testing the MTF of lenses) come close, although you can't 'see' the results as the testing is quantitative, not qualitative like Bryan's. They tested a EF 85mm f/1.2L II on both a 5DII and a 50D (15 vs. the 18 megapixels of the 7D, but pretty close). The data are presented as line widths per picture height (LW/PH), which is a resolution measurement that's a surrogate for sharpness. The results were:
85mm f/1.2L II @ f/1.2 on 50D: 2400LW/PH at thecenter, 2075LW/PH at the border
85mm f/1.2L II @ f/1.2 on5DII: 3157LW/PH at the center, 2120LW/PH at the border
So, from those data, the lens 'seems' sharper on a FF than on a recent crop body at the center - ~30% sharper. At the border, performance is identical (the numbers are±10% or so). Of course, that's partially a reflection of the fact that the picture height of the 5DII's sensor vs. the 50D - the 5DII's sensor is ~18% taller, meaning the relative sharpness of the lens on the two bodies is not very different (in fact, the difference would fall within the ~10% measurement error, meaning from a statistical standpoint, there's probably no significant difference in those measurements). At the borders, the resolution of the 85L on FF is no better than at the borders of the 1.6x crop sensor.
Although the 50mm f/1.2L was not tested on the 50D, it was tested on the 5DII, as was the 85mm f/1.8, which was also tested on the 50D (the two lenses from our previous comparison), and those results are worth mentioning:
50mm f/1.2L @ f/1.2 on5DII: 2473 LW/PH at the center, 1332 LW/PH at the border
85mm f/1.8 @ f/1.8 on5DII: 3082 LW/PH at the center, 2916 LW/PH at the border
85mm f/1.8 @ f/1.8 on50D: 2267 LW/PH at the center, 2183 LW/PH at the border
So, from these and the above results, I conclude the following:
- The 85mm f/1.8 is an optically excellent lens - as sharp at f/1.8 at the center as the 85mm f/1.2L @ f/1.2 with either the 5DII or the 50D, and the non-L lens is actually sharper wide open at the borders than the L lens wide open on both bodies(a reasonable penalty for being at f/1.2!)
- The 85mm f/1.8 has such good resolution, sharpness is not a reason to get the 85mm f/1.2L II regardless of the body you have - in fact, based on sharpness, I'd argue that getting the 85mm f/1.2L II for a FF body is a waste of money, as much as for getting it for a crop body. But sharpness isn't everything - DoF, an extra stop of light, and color/contrast/bokeh are big advantages.
- Both of the 85mm lenses are significancy sharper at their respective maximum apertures than the 50mm f/1.2L @ f/1.2.
- 'Simulating' the effect of sensor cropping by comparing resolution of the85mm f/1.8 @ f/1.8 on FF to the 50mm f/1.2 @ f/1.2 on 1.6x is just plain unfair (and invalid) because of the dramatic differences in optical performance between those lenses even on the same body - the 85mm f/1.8 is simply sharper wide open than the 50mm f/1.2 (presumably because Canon chose to design the lens for better bokeh at the expense of sharpness).
I can't say for sure what significance these MTF measurements have in terms of 'real world' performance. But, if you compare those numbers to the visual appearance on Bryan's ISO 12233 charts, they are well aligned (for example, the 85mm f/1.8 @ f/1.8 is sharper in the corners than the 85mm f/1.2L @ f/1.2).
If those numbers are at all accurate as a comparable measure of performance of a given lens on different cameras, it suggests the 85L would not be dramatically better on FF than on a 1.6x crop - at least, in terms of sharpness. Likewise, color and contrast should be equivalent. Obviously, there are other factors - DoF and bokeh being huge ones in terms of image characteristics, and as I stated previously regarding the bodies themselves, sensor differences in terms of noise performance are significant.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
Keith, is that an offer to perform such a test? [img]/emoticons/emotion-13.gif[/img] You seem to have the necessary components (85L, 5DII, and 7D)...
Well I won't have the 85L until Monday but I did compare the 35L on both. The pixel density actually makes the 7D's image larger which actually threw me when I opened them to 100% in PS. Then I notice how poorly the ISO chart printed out of my laser printer. I didn't post them due to the quality and confusion. It still gave me an idea of how much sharper the 5DII's image was. The 35L is mind boggling sharp on the 5DII with just a +2 MA. I'll redo it Monday after the 85 arrives or if you want to see the 35L again since it is comparing the sensors, I can reshoot with a dollar bill or something.
It's funny how confusing it is, with the pixel density the small sensors image is actually larger just cropped. This is too much for my wee non-scienctific brain.
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Re: Wallet full of $100 bills
Wow! I have beenaway for about a week and this thread is huge! Oh well, time to start reading!
John.
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Re: Wallet full of $100 bills
Okay. I don't think this will ever help anything. I couldn't think of anything better to shoot. The 7D looks better, the pixel density cause magnification over the 5DII. I probably didn't do this the best either. If anyone has any suggestions on how to do this better, I'm willing.
These are exact pixel representation. I can understand now how the smaller pixels exploit lens deficiencies.
5DII
[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.25.81/5DbarcodeC.jpg[/img]
7D
[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.25.81/7DbarcodeC.jpg[/img]
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Keith B
Okay. I don't think this will ever help anything. I couldn't think of anything better to shoot. The 7D looks better, the pixel density cause magnification over the 5DII.
Thanks for taking the time to satisfy (perhaps) our collective curiosity!
I don't know that I'd say the 7D looks better - but I can't say that it looksworse, either - as I said above, either way, the difference is certainly not dramatic. I'm not saying that FF doesn't have advantages over crop in terms of IQ - but apparently not in sharpness between these two cameras, which is fine. Keep in mind, the sensor technology improved somewhat between the 5DII and the 7D (e.g. gapless microlenses).
Keith, if you turned down the lights and raised the ISO a bit, you'd see a difference in noise (in fact, the 7D image above looks like it already has slightly more noise than the 5DII).
Jon, I'm not sure if this 'convinces' you that the main differences in terms of images here are angle of view and DoF with a given lens, and noise performance. Clearly, the DoF of f/1.2 on FF is never going to be possible on a 1.6x crop body. As I tried to show above, the IQ differences you were highlighting in your example of FF vs. crop (85mm f/1.8 vs/ 50mm f/1.2L) were principally due to inherent differences in the lenses, not the sensors. Keith's test here, with the same lens on both of the relevant cameras, really supports that assertion.
--John
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Re: Wallet full of $100 bills
These were shot at ISO 100. I'll redo this Monday night after I get the 85L. I'LL use a higher ISO also. I'll post pics of micro-adjustment process too. Since I had never had my 35L on the 7D I had to do MA on it order to make it a fair demo. I was kind of taken how less shallow the DOF of 1.4 was on the 7D.
Yeah after looking at them again, it is just that the 7D image is magnified. When I first mention this test I didn't take in account about pixel density and I was thinking the magnification would be the same if the camera didn't move.
I think somewhere back in this thread it was mentioned about barrel distortion differences. I think the difference between a gapless pixel sensor and one with gaps might have slight effect on that (maybe). It seems when the pixels from are slid together they could exaggerate the effect ever so slightly. On a gapless there is no adjusting.
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Re: Wallet full of $100 bills
Thanks, Keith. Do I understand correctly that these were both shot with the 35L wide open? If so I'm impressed with the IQ of the 35L.
It's hard for me to tell which is sharper. The 7D shows more detail (as expected, just because the image is bigger) but the 5DII looks sharper (again as expected because the chart is smaller). Ideally, one would frame the chart the same way in both cameras, then
resize the larger (in terms of resolution) image to the smaller.
There seems to be a good deal more CA in the 7D image (again, this is expected: when you crop, you magnify CA along with all the other aberrations).
Once again I'm impressed with the IQ of the 35L... the situation here is probably more pixel limited than I would have guessed.
Quote:
Originally Posted by neuroanatomist
Jon, I'm not sure if this 'convinces'
you that the main differences in terms of images here are angle
of view and DoF with a given lens, and noise performance.
That's right, it does not[:)]
While it is an interesting
comparison and I appreciate Keith's posting, I don't see this as
relevant to what I was talking about. To me the relevant comparison is
between two systems that take the same pictures (if we find a 22mm f/0.875, we can
put it on the 7D and compare to the 35 f/1.4 on the 5DII [:P] )
Quote:
Originally Posted by neuroanatomist
As I tried to show above, the IQ
differences you were highlighting in your example of FF vs. crop (85mm
f/1.8 vs/ 50mm f/1.2L) were principally due to inherent differences in
the lenses, not the sensors.
I don't believe that at all. I
still believe that differences in IQ between two high quality primes
(even between a $400 prime and a $1500 prime) are overwhelmed by the
difference in the sensor size. Don't you think that if we reversed the lenses (ie, stopped down the shorter lens and cropped the longer), the stopped down lens would come out ahead?
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
Thanks, Keith. Do I understand correctly that these were both shot with the 35L wide open? If so I'm impressed with the IQ of the 35L.
It's hard for me to tell which is sharper. The 7D shows more detail (as expected, just because the image is bigger) but the 5DII looks sharper (again as expected because the chart is smaller). Ideally, one would frame the chart the same way in both cameras, then
resize the larger (in terms of resolution) image to the smaller.
There seems to be a good deal more CA in the 7D image (again, this is expected: when you crop, you magnify CA along with all the other aberrations).
Once again I'm impressed with the IQ of the 35L... the situation here is probably more pixel limited than I would have guessed.
No problem. Both samples are the 35L opened all the way at 1.4. It is a a great, fun lens. That is why I say don't hold your breath for mark II version. IMO, CA is the lens' only weakness and in some instances can be pretty strong.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
Quote:
Originally Posted by neuroanatomist
As I tried to show above, the IQ
differences you were highlighting in your example of FF vs. crop (85mm
f/1.8 vs/ 50mm f/1.2L) were principally due to inherent differences in
the lenses, not the sensors.
I don't believe that at all. I
still believe that differences in IQ between two high quality primes
(even between a $400 prime and a $1500 prime) are overwhelmed by the
difference in the sensor size. Don't you think that if we reversed the lenses (ie, stopped down the shorter lens and cropped the longer), the stopped down lens would come out ahead?
In that case, we'll have to agree to disagree, I suppose. Look at the photozone.de MTF numbers for these two lenses -50mm f/1.2L @ f/1.2 on5DII: 2473 LW/PHvs. the85mm f/1.8 @ f/1.8 on5DII: 3082 LW/PH (the 85 1.8 is ~25% sharper by the numbers) on the same body. Bryan's ISO 12233 comparison of those two lenses shows clearly that the 85 f/1.8 is sharperon the same body.
Lenses, even 'high quality primes', are different. Hopefully, you can acknowledge that fact - if not, I'm not sure what else it would take to convince you.
Because of the crop factor, you're going to have differences in angle of view with the same lens on different cameras. There's no way to correct for that by using different lenses to compare the systems - different lenses are different lenses.
I suppose you could use a zoom lens on each body, and keep the subject distance the same, using the zoom to 'simulate' the effect of the crop body apparently changing focal length. You'd stop down the zoom to 'simulate' the apparent effect on aperture. If you used a high quality zoom like the 70-200 II, which doesn't get appreciably better as you stop down from wide open, that would be a fair comparison. I'd bet real money that if you did that, you'd see about the same difference that Keith saw with the 35L - i.e., almost none if shot at ISO 100.
The two systems in question have different sensors - they aren't going to take the same pictures. The only reasonable way to perform that comparison is to use the same lens with a different distance from the subject, and live with the fact that perspective and compression are different. That way, you are comparing bodies. You cannot change both lenses and bodies and expect to compare the two systems. You need to perform two independent comparisons each with one constant and one variable. Keith's comparison came pretty close to a 'real' comparison of the two bodies, and confirmed for me that there's very little difference in sharpness between the 7D and the 5DII. As I've said, ISO noise is a clear differentiator.
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
In that case, we'll have to agree to disagree, I suppose. Look at the photozone.de MTF numbers for these two lenses -50mm f/1.2L @ f/1.2 on5DII: 2473 LW/PHvs. the85mm f/1.8 @ f/1.8 on5DII: 3082 LW/PH (the 85 1.8 is ~25% sharper by the numbers) on the same body.
But that's comparing the lenses wide open and uncropped. The result is exactly as expected: the slower uncropped lens wins. This isn't what I meant by "switching the lenses". I meant, instead of making the 50mm faster and cropping it, make the 85mm faster and crop it.
Quote:
Originally Posted by neuroanatomist
The two systems in question have different sensors - they aren't going to take the same pictures. The only reasonable way to perform that comparison is to use the same lens with a different distance from the subject, and live with the fact that perspective and compression are different.
They wont take exactly the same pictures, of course. One will have better IQ. But you can compare two systems, one FF and one APS-C in which each system has the same framing, same working distance, same DOF, same compression and same noise. Yes, the two systems will use different lenses, and this effects the outcome. But if I consistently get far better IQ taking the same picture (modulo IQ) with cheaper lenses using one of the two systems, that's the one I want.
Quote:
Originally Posted by neuroanatomist
You cannot change both lenses and bodies and expect to compare the two systems.
This is the core of our disagreement. I say you not only can change the lens, you *must* change it. You must compare systems with the same *effective* focal length and *effective* f numbers. You seem to feel we must compare systems with the same actual focal length and same actual f number.
Quote:
Originally Posted by neuroanatomist
You need to perform two independent comparisons each with one constant and one variable.
I agree. But I think you're using the wrong variables. If we change the point (3,4) in Cartesian coordinates to the point (6,8), we've changed two variables because x and y both changed, right? Maybe. But in polar coordinates, I've kept theta the same, and only changed the variable r.
Keep everything else the same and change only the sensor. Yes, you have to change the lens, too. That's too bad. Try to choose lenses that aren't too different. (Don't compare a cheap zoom to an expensive prime, for example). One system will consistently win, and the lenses you need to perform the test for that system will consistently cost less.
If you insist that it makes sense to compare IQ in systems that take pictures with different DOF, compression, exposure time, etc, then I agree that we must agree to disagree (don't read that ten times fast [:)])
Anyone else out there want to weigh in? Is anyone else still there? Can you say "hijacked thread"? My apologies, John. :)
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
Anyone else out there want to weigh in? Is anyone else still there?
Sigh....haven't been active the last few days and I missed A LOT on this thread obviously [:P] Outlook almost considers this thread as SPAM [;)]I'm not sure if I do want to catch up though [A] It's a lot of technical talk, but I might give it a try when I got more time...like two weeks time [8-|]
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
But that's comparing the lenses wide open and uncropped. The result is exactly as expected: the slower uncropped lens wins.
You're saying that the 85mm f/1.8 'wins' because it's slower, and becauseit's a longer focal length (no cropping). Yes, the 85mm f/1.8 does win, for sharpness. But not because it's slower and not because it's uncropped/longer. It 'wins' because it is a sharper lens (as I and many reviewers have said, because Canon designed the 50mm f/1.2L to favor bokeh, not sharpness).
Let's extend the comparison in the same direction - compare the 85mm f/1.8 with a lens that is just about exactly 1.6x slower and longer - the 135m f/2.8 Softfocus. In that comparison, the shorter, faster lens is a bit sharper - it still 'wins', with both lenses wide open. Why is the 135mm f/2.8 softer? If you tell me that the slower, longer lens is softer because it's just not as well-designed a lens in terms of sharpness, well...you're right. Of course, if that's your reason...you'll also have proved my point about the 50 1.2L vs. 85 1.8 comparison. If you have another reason, well, I'd be interested to know what that is!
Now, the 135mm f/2L is slower and longer than the 85mm f/1.8, and it's also sharper wide open than the 85mm f/1.8 - but again, because it's simply a sharper lens, not because of the aperture or focal length. The 135mm f/2L is sharper than the longer, slower EF 200mm f/2.8L II for the same reason, it's just a damn sharp lens!
Quote:
Originally Posted by Jon Ruyle
But if I consistently get far better IQ taking the same picture (modulo IQ) with cheaper lenses using one of the two systems, that's the one I want.
So, a slower, longer, cheaper lens will give better IQ on a FF than a faster, shorter, more expensive lens will give on a crop body. In that case, someone with a crop body who needs the 'normal' FF-equivalent angle of view shouldn't even consider the 35mm f/1.4L that Keith just showed us is very sharp on a crop body. Instead, they should go FF and just get theslower, longer, cheaper EF 50mm f/1.8 II - that lens will have better IQ on a 5DII than the35mm f/1.4Lon a 7D. At least, that's what your statements indicate. If you can prove to me that the nifty-fifty has better IQ on a 5DII than the35mm f/1.4Lon a 7D, I'll buy a 5DII - and I'll give you my 7D!
The other factor is that a system has many parts and features. The faster frame rate and better AF tracking are significant differences between the 5DII and the 7D. If the 5DII with it's better IQ misses a shot because the subject was running toward you too fast for the AF to track it, or misses the perfectly-timed action shot of the burst because it's frame rate is half as fast as the 7D, better IQ doesn't help.
To frame this discussion a little differently, I think it may help to differentiate between imagequalityand image<span>characteristics. 'Quality' comprises factors like sharpness, noise, color, and contrast. 'Characteristics' comprise factors like depth of field, perspective, and angle of view.
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The 50mm f/1.2L on the 7D will have similar image 'characteristics' to the 85mm f/1.8 on the 5DII - but, the image quality will be different, because of the inherent differences in the lenses.
I think it's possible to 'simulate' differences in image characteristics by using different lenses on different bodies - butnotpossible to compare image quality by using different lenses on different bodies. My contention is that when comparing the 7D and the 5DII, themaindifferences (with the notable exception of noise) will be in the image<span>characteristics.
IMO, if you take an excellent prime like the 85mm f/1.2L II and put it on the 7D vs. the 5DII, the main differences (again) will be in the image characteristics, not the image quality (as I've defined them).
From that perspective, you're absolutely right aboutchoosing a system where thelenses you need to perform 'better' will consistently cost less. But better is relative. If 'better' means shallowerdepth of field, ok - the cheap, slow lens on FF wins. If 'better' means narrower angle of view to avoid the need to crop away resolution, the crop body wins, especially from a cost perspective at the supertelephoto end. In terms of image quality, the FF will win for noise, no question. Sharpness, color and contrast are all critically dependent on the lens, and much less dependent on the sensor.
Not sure if we can agree on that (I suspect the answer there is 'no'). But, we can agree to disagree, 'eh?
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Re: Wallet full of $100 bills
I wont have time to reply fully until tomorrow (I've got to put the kids to sleep, then early to bed to get up at 4:30am :) ).
But one statement you made *really* caught my eye.
Quote:
Originally Posted by neuroanatomist
If you can prove to me that the nifty-fifty has better IQ on a 5DII than the35mm f/1.4Lon a 7D, I'll buy a 5DII - and I'll give you my 7D!
According to photozone, the 35 f/1.4 @ f/1.4 on an APS-C has the following MTF 50:
Center: 1873.5
Border: 1574
Nifty fifty @ f/1.8 on 21mp full frame:
Center: 2821
Border: 2460
Extreme border: 2359
Don't worry. I'm not ready to take your 7D yet [:)]
We're comparing an 8mp APS-C to a 21mp full frame, which is unfair, I admit. If *only* they had done the test with a 15mp APS-C I'd have my proof!
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Re: Wallet full of $100 bills
Ok, I have backtrack this thread and have come to a conclusion. FF is better than 1.6 so I will get a FF. Simple.[:D]\
Although using a longer slower lens is in a sense unfair but is inherente in the two optical systems. But is't that great? Same DOF for a slower cheaplens, andsharper for the same apparent DOF.
John.
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Re: Wallet full of $100 bills
On 8mp APS-C, the 85 f/1.8 has similar results wide open to the 35 f/1.4. Photozone tests the 85 on both 8 mp and 15 mp APS-C.
On 15mp APS-C, the results are:
Center: 2267
Border: 2183
Assuming the 35 f 1.4 which has similar scores at 8mp also has similar scores on the 15mp APS-C, it would still fall far short. I admit that isn't proof. But, well, I pretty confident that the nifty fifty *would* win this. (But then, I was pretty confident of that before looking at photozone [:)])
Hopefully I didn't mess up any of this data... I'm in more of a hurry than usual.
I've gotta put the kids to sleep :)
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Re: Wallet full of $100 bills
Quote:
Originally Posted by Jon Ruyle
We're comparing an 8mp APS-C to a 21mp full frame, which is unfair, I admit.
Yeah - PZ's wide open center MTF for the 85mm f/1.8 is 1813 with the 8 MP 350D, and 2267 on the 15 MP 50D.
If Keith's test with the 35L didn't convince you that the 7D can deliver images with (approximately) the same quality as the 5DII, I guess we have no choice but to agree to disagree...
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Re: Wallet full of $100 bills
I haven't read too much of this thread (mostly because it's ENORMOUS!!!) but I will say one thing - I a little jealous that Keith gets to play with both the 5D MkII and the 7D.
[:D]
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Re: Wallet full of $100 bills
Quote:
Originally Posted by neuroanatomist
If Keith's test with the 35L didn't convince you that the 7D can deliver images with (approximately) the same quality as the 5DII, I guess we have no choice but to agree to disagree...
Sensor only the 7D and 5D II are not even close in terms of sharpness WITH the same lens. I downloaded Bryansnoise cropsand I needed a lot moresharpening tostillget inferior results to the 5D II,downrezed to the same resolution and at native resolution. I used 85 units for the 5D II and I needed 110 units for the 7D.
John.
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Re: Wallet full of $100 bills
I couldn't tell anything really from my test. The difference in magnification made it impossible to tell and therefore not a good way to compare them at all IMO. At first it seemed right but I'm kind of a dumb guy.
I'm definitely not a pixel peeper but I don't mind helping out if anyone has a different test they'd like to see. I saw the zoom theory mentioned. I don't have the mention 70-200 II but I have the mk I, 16-35II and 24-70 if anyone wants to see the results from any of those lenses. I think the 24-70 is pretty consistent through out the range.
