Re: Canon Releases Six New L-Series EF Lenses And Accessories
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Originally Posted by neuroanatomist
[You might find [url="http://www.bobatkins.com/photography/technical/field_of_view.html]Bob Atkins FOV Calculator[/url] handy (scroll down a bit) - you can enter focal length, crop factor, and distance and it will calculate the XY dimensions of your field.
For example, with a 300mm lens on a 7D, at 15 feet from a subject, the FOV is 13.5x9". If that subject is a pretty, yellow goldfinch on a branch, that 4" tall bird will occupy 6.6% of the image frame. With a 400mm lens in that scenario, the bird will occupy 11.7% of the image. Either way, the shot is probably going to require some cropping, but the extra 100mm of focal length means only about half as much cropping, and therefore less noise in the final image. Then again, if all you intend is posing images here and printing 4x6" photos, crop away...
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First of all, I should say that I agree with the point you are making (and thanks for taking the time to respond). Playing with the analysis a little more, at 18 MP (5184 x 3456), the FOV at 15 ft300 mm has <span style="text-decoration: line-through;"]232 horizontal pixels per inch and 386 <span style="text-decoration: line-through;"]vertical pixels per inch. The 400 mm has <span style="text-decoration: line-through;"]310 horizontal ppi and 515 <span style="text-decoration: line-through;"]vertical ppi. Throw in the fact that the 70 to 300 L is sharper, I am thinking that I'd still have a good picture of the goldfinch at 15 ft. Maybe not AS good, maybe I would lose some ability to crop or enlargea print. So, this is the potential compromise, weight/size/limited to 300 mm vs cost/having 1 lens instead of two/some aperture benefits. Definitely has me thinking.
Anyways, I can't wait for the review. [:D]
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I believe I just found an error in my calcs (thus the strikethroughs). Also, others probably know, but resolving power appears to be linear with focal length. Thus the gain in resolving power is the same from 200 mm to 300 mm as it is from 300 mm to 400 mm. FOV is not linear.
Re: Canon Releases Six New L-Series EF Lenses And Accessories
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Originally Posted by Sheiky
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Originally Posted by neuroanatomist
Tom, Jan - where are you getting the information that this lens doesn't extend with zooming?
You're right, my imagination and drooling played a big role in saying this I think ...If I would look at the picture I would be tempted to say it as well, but indeed I'm not sure.
Looks like it extends with zooming. The Canon Digital Learning Center article on the new lens shows the optical diagram, which shows the front element of the lens extending with increasing focal length.
Re: Canon Releases Six New L-Series EF Lenses And Accessories
There has been discussion about the 70-300mmL with extenders. I just noticed on the Canon Learning center article on the 300/400+extendersthat the new 70-300L isn't listed as compatible. Search for "Lens Compatibility" to see the chart of supported lenses.
Re: Canon Releases Six New L-Series EF Lenses And Accessories
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Originally Posted by JJphoto
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Originally Posted by HDNitehawk
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Originally Posted by JJphoto
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Originally Posted by neuroanatomist
That gives me an idea - since I'm a neuroscientist working for a pharmaceutical company, maybe I should push for development of a drug to treat <span style="color: #ff0000;"]L-disease. [img]/emoticons/emotion-15.gif[/img]
I guess I have different type of L disease, my symptom is that instead of using different lens for different situation, I tend to use my 300mm 2.8 for everything to get best IQ I can, sure sometimes it looked so ridiculous by holding a big white lens in my kids kindergarten but couldn't help it at all... and I guess there is no drug for that since we want to be sick like that. sorry, sounds like way off the subject.
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This is classic confirmed "L Prime".If you find yourself saying things like "nothing but the best IQ will do" and "I can always crop, I don't need a Zoom" then you may have the first tell tale signs.
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thank you Doc for your correct diagnosis , but I don't want to be treated anyway[img]/emoticons/emotion-2.gif[/img]
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Not a Doc.I am a fellow suffer that just knows the symptoms. I can relate to your kindergaten story. I have grandsons who play baseball andwhohave there games photographed with the same gear that the big league players making millions do. And I have birds in the back yard who get their picture taken with the same stuff asthe ones on the front of national geographic. L Prime addicted.
Re: Canon Releases Six New L-Series EF Lenses And Accessories
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Originally Posted by DavidEccleston
That's what I thought, but I wasn't positive:
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Originally Posted by neuroanatomist
I don't believe that I read anywhere that this new 70-300mm f/4-5.6L is compatible with the extenders...It depends on the physical configuration of the mount end of the lens, and whether or not there's room for the protruding optical element of the extender to fit into the back of the lens. I'll point out that the extenders do not fit into the back of the 70-300mm non-L lenses, and that the new 70-300mm L lens is the same physical length as the old 70-300mm non-DO, meaning a pretty compact design.
Given the compact design of the new lens, there's no room at the back end for the protruding optical element of the extender.
Interestingly, looking at the optical design Canon showed for the new 70-300mm L, it looks like with the floating element design, the rear element also moves with zooming (between 135mm and 300mm). I don't know a lot about zoom lens design (microscopes don't have zoom lenses!), but I hope there's a clear glass cover at the back end - if the rear element moves with zooming and there's nothing between the rear element and the sensor, Canon must think their anti-dust sensor coating and vibrating sensor cleaning are really effective...
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Re: Canon Releases Six New L-Series EF Lenses And Accessories
Canon EF 70-300mm f/4-5.6L IS USM lens
It certainly looks like this lens extends when it zooms. So the question is as follows...if it extends..why bother with the weathersealing? When the lens extends it must create a weakspot that the non-extending lenses do not have, right? How do you properly seal the area where the lens creeps outwards? When it retracts it must be hard not to pull moisture and dust back inside the body of the lens.
Dan
Re: Canon Releases Six New L-Series EF Lenses And Accessories
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Originally Posted by neuroanatomist
I noticed...we'll see what it will look like [^o)]
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Originally Posted by Ulfarin
.if it extends..why bother with the weathersealing? When the lens extends it must create a weakspot that the non-extending lenses do not have, right?
Uh...the 24-70L, 24-105L are also weathersealed extending zoom-lenses... And as far as I know they work great.
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Originally Posted by Ulfarin
How do you properly seal the area where the lens creeps outwards? When it retracts it must be hard not to pull moisture and dust back inside the body of the lens.
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I have no clue. I wondered myself a couple times since when I dry my 24-105 after rain when it's extended and I pull the extended part back in and out it will be wet again, so there must be some rubber sealing or something inside the barrel.
No clue, but I bet you can find the answer online.
Jan
Re: Canon Releases Six New L-Series EF Lenses And Accessories
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Originally Posted by Ulfarin
How do you properly seal the area where the lens creeps outwards? When it retracts it must be hard not to pull moisture and dust back inside the body of the lens.
Perfect application for an o-ring or two.
Tom
Re: Canon Releases Six New L-Series EF Lenses And Accessories
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Originally Posted by Tom Wertman
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Originally Posted by Ulfarin
How do you properly seal the area where the lens creeps outwards? When it retracts it must be hard not to pull moisture and dust back inside the body of the lens.
Perfect application for an o-ring or two.
Tom
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I've found it interesting in reading descriptions of several "L" lenses online thatvery few are stated as"weather proof" and most others, including the 70-300 L are listed as "weather resistant." Perhaps to the author, those aren't that different, in my world, those are very different.A couple of o-ringson an extending tube are probably"weather resistant."
As for me, I am still interested in the 70-300L, but I think I've decided to rent the 70-200 f/4 L IS and the 100-400 L. I have a trip coming up to Acadia NP, anyone recommend one lens rental shop over another? Thanks.
Re: Canon Releases Six New L-Series EF Lenses And Accessories
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Originally Posted by Kayaker72
A couple of o-ringson an extending tube are probably"weather resistant."
That is all most of us need. There are a variety of covers for lens and body if one plans on being out in a downpour or underwater.
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Originally Posted by Kayaker72
I have a trip coming up to Acadia NP
Went there last summer. Great park, very rocky without a lot of trees. Most of the top soil was pushed south by the glaciers. 90% of my shots required a wide lens (24-105 4L). The landscape is awesome. Did not have much use for telephoto.
Tom
