Lots of Focus Points

<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language: EN-US;"]<o:p><span style="font-family: Calibri; font-size: small;"]</o:p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language: EN-US;"]<span style="font-size: small;"]<span style="font-family: Calibri;"]With the impending release of the 1D X with its lots of focus points. There has been a lot of discussion about how good this will be. From all of the information I have gleaned from books, articles and even professional photographers, they have all talked about using a single focus point. <o:p></o:p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language: EN-US;"]<o:p><span style="font-family: Calibri; font-size: small;"]</o:p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language: EN-US;"]<span style="font-size: small;"]<span style="font-family: Calibri;"]Well at the risk of highlighting my ignorance, when do you use lots of focus point?<o:p></o:p>

On my 7D, with its glorious number of 19 AF points, I generally only ever use the

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Originally Posted by Raid

<p class="MsoNormal" style="margin:0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language:EN-US;"]<span style="font-family:Calibri;font-size:small;"]
<p class="MsoNormal" style="margin:0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language:EN-US;"]<span style="font-size:small;"]<span style="font-family:Calibri;"]With the impending release of the 1D X with its lots of focus points.... From all of the information I have gleaned from books, articles and even professional photographers, they have all talked about using a single focus point.
<p class="MsoNormal" style="margin:0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language:EN-US;"]<span style="font-family:Calibri;font-size:small;"]
<p class="MsoNormal" style="margin:0cm 0cm 0pt;"]<span lang="EN-US" style="mso-ansi-language:EN-US;"]<span style="font-size:small;"]<span style="font-family:Calibri;"]....when do you use lots of focus point?

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I'll make an attempt to clarify what I thinkis happening depending on which article you read, some of the reviewers use the term "single AF point" and that confuses people with "single center" AF point. There are two ways of selecting AF points; one is by letting the camera decide called "Automatic AF Point selection," and the other way is by "Manual Point selection" in which you decide which point to select.


People can let the camera choose between "a lot of AF points" when using Automatic AF point selection, that is when the camera decides which sensor points it should use, but that is very unreliable since the camera is technically guessing what you would like to focus on. The camera usually focuses on the forward most subject in the frame or the subject with the most contrast. Most people except for beginners will never use this setting.


I'm less familiar with the new 1D X focusing system, but hopefully I can clarify what the confusion may be, when you're reading about the AF specs. For example, on the 1D MKIV, when choosing Automatic AF point selection (letting the camera choose the points) with an f/2.8 Lens, the camera will only choose amongst 19 points for Camera decided AF point tracking, however when the photographer selects a "single point AF selection manually," that means that they have chosen where to start the tracking process amongst the 45 points that are available (this becomes more accurate since you will pick the correct point that benefits your subject regardingthe compostional starting point.Theuserwill now have45 points to choose from ("also a lot") for tracking (39 of those points are cross sensitive and 6 are horizontal sensitive) when using an f/2.8 lens.


I think the terminology confuses people, since "single point manual point selection" sounds like there are less points available to you (because of the word "single") as oppossed to Automatic AF selection, however, remember that this single point is just where the AF starts but you also haveother points (45 points) availableto choose from when compared to Automatic AF point selection (19 points). A better term than single point, would be "manual point selection," but since it's AF and not manual focus, they sometimes call it "Single Point" AF Manual selection. Single point AF manual selection does offer"a lot" of AF pointsfor AI Servo tracking.


Another term is "the single center point"when someone chooses this,they are in fact limiting the focus point to onesingle "center point" only, which on lower camera models is the most accurate, however, when you go up the Canon line to the more expensive models like the 1D MKIV, then the 39 cross sensor points are still very accurate for AI Servo tracking, plus you have more points availableto choose from.


So when you're reading these articles note the difference between "Single point AF manual selection" and the difference between "Single center point selection" and "Automatic AF Point selection".


I hope you got mypoint.


Rich

I think Rich's explanation is excellent. To summarize, most photographers use 'single point' in that they select which AF point to use, rather than letting the camera do that for them. Generally speaking, having more points is better for AI Servo tracking of moving subjects. Having lots of points could make manually selecting a point slower, e.g. 5 presses of the joystick to get from center to side, but previous 1-series bodies have have C.Fn options to limit the number of available points for manual selection, and likely the 1D X will have similar options.

To expand on what neuro said, using a single point is great for portrait work, macro work, etc. Especially when using a shallow depth of field. i.e. using a single af point to focus on the eye of your subject. Like him, I also use more points for fast moving subjects like wildlife (never know when they

Raid, The two big reasons I like the idea of "lots of focus points" are as follows:


1. When you select a focus point, it doesn't have to be the middle one---the more focus points you have the more likely you are to have one that falls where you want on the subject, such as an eye. More focus points normally offer greater frame coverage (although this hasn't always been the case, for the 1DX they have spread more focus points over a wider area of the frame--acoording to he literature.


2. When shooting sports, wildlife or fast moving subjects, I like using zone focus where the camera selects the point based on the zone or area of the frame you are trying to keep on the subject. The more points you have, the larger or more variety of zones will be available.


hope this helps

Thanks everybody


I have never attempted to use lots of focus points before, I will give it a try and see what happens.

Thanks everybody


I have never attempted to use lots of focus points before, I will give it a try and see what happens.

Raid,


The goal is not to arbitrarily use lots of focus points at once, it's more about selecting the right point or points for better precision and tracking composition. The goal is to only have the camera focus on your subject while ignoring the other components in the frame.You'll have lots of focus points to choose from by using "single point" AF manual selection. You can choose these points by using the multi-controller or the manual AF point selection button (in the back of the camera). I'm not sure which camera you have. Once you select your point, then you'll want to have that point locked onto your subject while you try to track it.


Once you understand this concept, then you can add "extra" focus points to your single point selection. You can add these extra surrounding points; above, below and to the sides of the single point that you had selected manually. These points will take over the focus if your single point should temporarily lose your subject. I highly recommend this feature when tracking difficult subjects.


As Bob has mentioned, the 7D also has zone AF which will allow you to pick a certain zone on the sensor for it to AF on your subject. So.., as long as you keep your subject in that zone then you'll be fine.


If you're interested I can go into more detail. Just let me know if you have any questions.


Rich

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Originally Posted by Bob Williams

More focus points normally offer greater frame coverage (although this hasn't always been the case, for the 1DX they have spread more focus points over a wider area of the frame--acoording to he literature.

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This subject comes up quite frequently. In fact, one of the (or at least, one of my...) chief complaints about the 5DII's Af system is the relatively inadequate spread of the AF points. Canon advertised the fact that they have the same lateral spread as the 1DsIII, but conveniently omitted the fact that the vertical spread was much less (a full 'row' of points less), meaning the 'corner' points of the 5DII come no where the rule of thirds.


A common question is, "What does the relative spread of AF points look like?" On the web, I ran across a file which has scaled versions of the focus screen representations of the AF points for the 1D IV, 5DII, and 7D. I took that file, and added in scaled versions of the points for the 1DsIII and the 1D X:


[img]/cfs-file.ashx/__key/CommunityServer-Components-UserFiles/00-00-00-35-15/xD_5F00_Focus_5F00_Screens.jpg[/img]


The 1D IV 7D are about tied for the broadest spread in both dimensions (relative to frame size). The 1D X has the same lateral spread as the 1D IV and 7D, and slightly less spread in the vertical dimension (about half a row shorter). The 5DII is in blue, and you can see the narrow spread relative to the other xD bodies.


The above image is pretty busy. But, if you click the image, you'll get a download of a layered pdf file. If you open that in Photoshop (CS, even Elements, I tried as far back Elements v6), you'll see each of the xD bodies' AF points in a separate layer of the file, along with a layer showing a rule-of-thirds grid. You can toggle them on and off as you like to compare the spreads.


Enjoy!


--John

Hmmm, doesn

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Originally Posted by Dr Croubie

The f/2.8-sensitive points, are completely controlled in firmware, not the amount of light. ...If i take an f/5.6 lens in bright sunlight, i get less AF points than with an f/2.8 lens in a candlelit room. Ditto with using an ND.


Why?

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It's not really about the amount of light, nor is it completely controlled in firmware. Daniel previously explained using a nice analogy, so I'll just paste his text from this thread: "<span>Imagine you are looking at the world through a 3cm cardboard tube. There is a 1cm hole in a wall, so when you look through the tube your view is restricted by the hole, not the tube. If the hole is expanded to 3cm, you'll have the maximum 3cm view possible. If the hole is expanded to 10 cm, the view is restricted by the tube, not the hole, so you can still only see 3cm. <span>The high precision f/2.8 autofocus sensor can only look at the world through an f/2.8 tube. If there is an f/5.6 hole in the wall, AF wont work. If the hole is expanded to f/2.8, then it will have an unobstructed view and work normally." Now, there's a little more to it than that, because f/2.8 is not a hard limit. But f/5.6 wouldn't work, even in bright sunlight. Nor does f/11 on an f/5.6 sensor with taped pins. Have you ever tried the pin taping? I did, with the 100-400mm + 1.4x II, and in bright light it's ok, but very slow and tends to hunt a bit, while in dim light it fails. Live View works, and is faster. I suspect Canon won't let it try because it's not very reliable, so from that standpoint, it's partly firmware.

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Originally Posted by Dr Croubie

Would it not be preferable to have a situation in which the camera meters the available light, and then decides on what AF points to enable/disable?

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It really seems that Canon took a stab at your idea, although not in quite the way you intend. Rather than relying on something variable, like amount of light, they coded in a known quantity - the lens you're using. As you can see on this translated page, they're pretty specific about which lenses can activate which AF points. The wide, fast primes and the 24-70mm only get one of the f/2.8 points, not all 5. The 28mm f/2.8 only gets the inner rows of f/4 points, and uses the outer rows of f/4 points at f/5.6. Since all these lenses have the same image circle, it must have to do with other optical properties that make those lenses less optimal with the higher sensitivity points. With some older, variable aperture zooms (and the 800/5.6) you start to lose even the f/5.6-sensitive points at the edges, dropping form 61 points to 47 points.


Macro lenses also 'suffer' - the 50mm f/2.5 and two of the100mm f/2.8 macro lenses L and old non-USM) don't even activate any f/2.8 points (they are f/2.8 lenses, right?!?), and the 100mm f/2.8 Macro USM doesn't get f/2.8 or even f/4 points. The 180mm f/3.5L Macro not only fails to activate f/4 points, but only gets the central 33 points out of the 61 available f/5.6 points. Probably not a big deal as MF is the norm for macro shooting, but I'm curious as to why the macro lenses take such a bit hit on AF point activation.

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Originally Posted by Dr Croubie

And on the spread of AF points on an APS-C body. Sure, there's a reason not to put them too wide because of vignetting, but if the camera detects an EF-mount (FF) lens, can't it enable some more AF points wider?

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Maybe on the 7D. But on all the other APS-C bodies, the AF points are etched onto the focusing screen. I'd think it would be pretty confusing to see them there, but not be able to select them. Imagine the tech support nightmare if they sold an xxD or xxxD with an EF-S kit lens, and users not being able to select some of the AF points they clearly see in the viewfinder.

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Originally Posted by Dr Croubie

True, there's other factors, like the size of the secondary mirror and AF sensor. But they just proved they can make a secondary mirror the size of an APS-Cframe move 12 times a second each way, and an AF sensor that size too.

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It's not the movement speed of the secondary mirror, it's size of the secondary mirror that limits the vertical extent of the AF point spread. <span>There is limited space behind the main mirror, based on the necessary geometry (i.e. the main mirror has to be at a 45&deg; angle to the incoming light, and the secondary mirror has to be behind the main mirror and at an angle of 90&deg; to the main mirror, so it's length is limited by the distance between the main mirror and the image sensor). You can see that in this cutaway schematic:


http://www.ted.photographer.org.uk/s...away_slr_t.jpg


That's why the 1D IV, 7D, and 1D X all have about the same vertical extent. As seen in the diagram I posted, the 7D, 1D IV, and 1D X have the widest horizontal spread, and it's the same for all of them. That suggests they are hitting the limit of how far apart they can be (yes, that's relative, and the actual spread of the AF points on the 7D is much less - but then, all the components of the mirror box are scaled down, too, so the limits are relative just like the spacing). And again, except on cameras with a transmissive LCD (currently only the 7D and 1D X), inactive AF points can't be hidden.

John


So this discussion gets confusing, as I am trying to figure out what the 1D X article is telling me in relation to the 500mm f4.


This is what the 1D IV book says:





Maximum f/stop: f/4


High-precision, cross-type AF with the center AF point is possible. The remaining 44 AF points will be horizontal-line sensitive only.


Which with the 1D IV I take this to mean I have one Cross Point and it is the center point only. Any other chosen would be second best, albeit that would probably be good enough.


So am I interpreting the 1D X charts wrong on the article, which I take it to mean we would get 21 cross type points instead of just one?


The 1D IV has a function with the supertele you can program the little button on the barrel and get several functions, one of which shrinks the size of the 1D IV center point, this is a good function for small birds in the bushes. I wonder if the 1D X will have the same function, I haven't found anything on this yet.








On another note


This is what the 1D IV book says about certain lenses





The following lenses and lens combinations have a maximum aperture of f/4, but cross-type focusing on 39 AF points is still possible as with lenses having an f/2.8 maximum aperture.


EF17-40mm f/4L USM, EF24-105mm f/4L IS USM, EF70-200mm f/2.8L IS USM + Extender EF1.4X II, EF200mm f/2L IS USM + Extender EF2X II, EF300mm f/2.8L IS USM + Extender EF1.4X II, EF400mm f/2.8L IS USM + Extender EF1.4X II


This kind of muddiesthe water and what was being explained about the f2.8 points and how many can be used. With my 500mm there is 1 point, with these combinations I can have as many as 39. It would make sense that Canon would focus intensely on these lenses to make them more diverse, since they are the bread and butter of the big league sports photographers and it is one of the best advertisements they can have.


Looking at the charts for the 1D X are we loosing some of the f2.8 cross points that we have going from the 1D IV to the 1D X?








Rick

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Originally Posted by HDNitehawk

So am I interpreting the 1D X charts wrong on the article, which I take it to mean we would get 21 cross type points instead of just one?


The 1D IV has a function with the supertele you can program the little button on the barrel and get several functions, one of which shrinks the size of the 1D IV center point, this is a good function for small birds in the bushes. I wonder if the 1D X will have the same function, I haven't found anything on this yet.

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Rick,


The 500mm f/4L IS and 600 f4/L IS will now have 41 cross type points on the 1D X. These are the blue and pink squares in the article below:


http://translate.google.com/translate?sl=auto&amp;tl=en&amp;js=n&amp;prev=_t&a mp;ie=UTF-8&amp;layout=2&amp;eotf=1&amp;u=http%3A%2F%2Fcweb. canon.jp%2Fcamera%2Feosd%2F1dx%2Ffeature-afae.html&amp;act=url


The 1D-X will still have spot focus for the super-telephotos and they have also added in camera support for spot focus for many other lenses.


Rich

Rich


I thought it might mean 41, but I wasn't sure if that is what the chart was trying to say. Our 1D IV booksayswe have one "High-Precision" cross type point when using the 500mm (f/4). I wonder how this would apply to the 1D X, if all points are considered equal ie: "High-Precision" or are the blue points going to be superior to the pink points?It looks like an improvement over the 1D IV, but it can't be a giant leap for me since my keeper rate for in focus pics is very high out of the 1D IV already.


Those moving from the 7D or 5D II will think they found the holy grail of AF systems if they make the move to a 1D X. Wich I guess they have since it will be the best available on a Canon.


Rick

<span>

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Originally Posted by HDNitehawk

<span>Looking at the charts for the 1D X are we loosing some of the f2.8 cross points that we have going from the 1D IV to the 1D X?<span>

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<span>Yes, you're losing some f/2.8 cross-type points, but gaining more f/4 cross type points. So, with an f/2.8 lens on 1D IV, you get 39 cross-type points, but with an f/4 lens you only get one cross-type point, with the exception of the list of lens and TC combos you posted above. With an f/2.8 lens on a 1D X, you'd get 25-41 cross type points (depending on lens), and you'd also 25-41 cross-type points with an f/4 lens. With an f/5.6 lens on a 1D IV (such as your 500/4 + 1.4x TC), you get zero cross-type points, whereas on the 1D X with an f/5.6 lens, you get 15-21 cross-type points (usually 21, as would be the case for the 500/4 + 1.4x).


<span>

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Originally Posted by HDNitehawk

Our 1D IV booksayswe have one "High-Precision" cross type point when using the 500mm (f/4). I wonder how this would apply to the 1D X, if all points are considered equal ie: "High-Precision" or are the blue points going to be superior to the pink points?

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<span>Something of a trade-off here. Prior to the 1D X, Canon bodies with a high-precision AF point only had one, the center point. On non-1-series bodies, that center point is high precision with an f/2.8 or faster lens, while on the 1-series, it is high precision with f/4 or faster lenses. The 1D X has 5 high precision points, but they require an f/2.8 or faster lens. So, your 500/4 on the 1D IV had a high-precision center point, whereas on the 1D X, your 500/4 will not activate a high precision point at all, not even the center one.


Lots of confusion here, lots of jargon. Time permitting, I'll try to post something that makes some sense of it all...

I think it will be helpful once they get the owners manual on line. Many of the questions everyone will be answered then.


Here is something I wonder as well. It has always seemed to me that the AF points and specifically the center point on the 1D IV covers a noticeably larger area than the 7D or 5D II seem to. I wonder with the new 1D X if the points will be smaller and much finer, since you are gaining so many new points.


Keep in mind I am not talking size of the etchings that you see when you get confirmation. I am talking actual area that the point focuses on which seems to be a larger area than the etching.

It's hard to say. The 1D IV and 1D X have approximately the same coverage, and the same number of 'columns' (11), but the 1D X has more 'rows' (7 vs. 5). But, how much 'blank space' between points exists on the 1D IV sensor? No idea...

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Originally Posted by neuroanatomist

<span>Yes, you're losing some f/2.8 cross-type points, but gaining more f/4 cross type points. So, with an f/2.8 lens on 1D IV, you get 39 cross-type points, but with an f/4 lens you only get one cross-type point, with the exception of the list of lens and TC combos you posted above. With an f/2.8 lens on a 1D X, you'd get 25-41 cross type points (depending on lens), and you'd also 25-41 cross-type points with an f/4 lens. With an f/5.6 lens on a 1D IV (such as your 500/4 + 1.4x TC), you get zero cross-type points, whereas on the 1D X with an f/5.6 lens, you get 15-21 cross-type points (usually 21, as would be the case for the 500/4 + 1.4x).


<span>

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John,


Isn't it true that if we have 41 cross type points that are f/4 sensitive on the 1D X, thenthose same 41 points will alsobe cross type points that are also f/2.8 sensitive. So, sincethe MKIV had 39 cross type points and the 1D X has 41 cross type points, then it means that we are actually gaining 2 extra f/2.8 cross type points and that we are not losing any.


In addition to gainingtwo moref/2.8 cross type points, we are alsoupgrading 5 points to higher precision "dual-cross" type points, out of the total 41 cross type points.


I don't think that the MKIV had any dual cross points, but I believe that you mentioned that the 7D hadone dual-cross type point at the center.


It's amazing that a lot of the 7D technology has found it's way to the 1D X or that the1D X technology made it's way to the 7D for testing. Either way,I always thought that the 7D was pretty advanced.


Thanks!


Rich

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Originally Posted by HDNitehawk

Rich


I thought it might mean 41, but I wasn't sure if that is what the chart was trying to say. Our 1D IV booksayswe have one "High-Precision" cross type point when using the 500mm (f/4). I wonder how this would apply to the 1D X, if all points are considered equal ie: "High-Precision" or are the blue points going to be superior to the pink points?It looks like an improvement over the 1D IV, but it can't be a giant leap for me since my keeper rate for in focus pics is very high out of the 1D IV already.
<div style="CLEAR: both"]</div>

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The blue points will bebetter than the pink points,for those using slower lenses. The solid blue points are newer dual cross type points, which means the point is an X with a cross layed over it. So, those will provide the most precision.


I don'town the 500mm f/4L so I never realized that, that lens only used one cross type center point. My 300mm f/2.8L IS with or without the 1.4X extender had 39 cross type points available on the MKIV. I agree that people using the500mm f/4L IS and MKIVcombo, never seem to have any complaints about it's AF ability.


I just thought of a new feature. Wouldn't it be cool if the focus points inside the viewfinder lit up "different colors" to let you know which type of focus point you were using, similar to the focus point graphics that we're looking at on the above link?


Rich

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Originally Posted by Richard Lane

I just thought of a new feature. Wouldn't it be cool if the focus points inside the viewfinder lit up "different colors" to let you know which type of focus point you were using, similar to the focus point graphics that we're looking at on the above link?

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It might be interesting tothose of uswho pour of camera specs so they know exactly what their camera is doing. But then all this information seems to go out the window in my brain when some rare bird or animalpops up in front of my lens. Usually all my brain puts together in that situation is thatthe red flashy light just told me the bird is in focus.


I am sure you would see multiple posts on this site with the title "what do the different colorAF lights mean?".

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Originally Posted by neuroanatomist

But, how much 'blank space' between points exists on the 1D IV sensor? No idea...

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You know this is frustrating. At some time in the past I found an article that actually shows this. It also had a detail of the actual area the af point covers in relation to each other. If I remember right it was put out by Canon.


I spent 30 minutes looking for it with no luck.

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Originally Posted by Richard Lane

don't think that the MKIV had any dual cross points, but I believe that you mentioned that the 7D hadone dual-cross type point at the center.


It's amazing that a lot of the 7D technology has found it's way to the 1D X or that the1D X technology made it's way to the 7D for testing. Either way,I always thought that the 7D was pretty advanced.

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Correct - no 1-series body before the 1D X has had a dual cross point, although the 7D has one...as do the 40D/50D/60D. Indeed, many of the 7D's features were brought to the series with the 1D X, or improved - you mentioned one earlier, Spot AF. It was interesting that Spot AF was available on the 1D IV, but only with a supertele lens attached, whereas on the 7D you can use Spot AF with any lens, which will be the case with the 1D X.

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Originally Posted by Richard Lane

In addition to gainingtwo moref/2.8 cross type points, we are alsoupgrading 5 points to higher precision "dual-cross" type points, out of the total 41 cross type points.

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True - but there's a trade off. Seems to be the story with the 1D X AF system. Yes, the 1D X brings 5 f/2.8 high-precision dual cross points to the 1-series...but it eliminates the ability to AF at f/8 with the center AF point, and while the center point of previous 1-series bodies operated in high-precision mode with an f/4 lens (like Rick's 500/4), the 1D X requires an f/2.8 lens for high-precision functionality with those 5 points.

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Originally Posted by Richard Lane

Isn't it true that if we have 41 cross type points that are f/4 sensitive on the 1D X, thenthose same 41 points will alsobe cross type points that are also f/2.8 sensitive. So, sincethe MKIV had 39 cross type points and the 1D X has 41 cross type points, then it means that we are actually gaining 2 extra f/2.8 cross type points and that we are not losing any.

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Technically, yes...but there's an additional implication that should be discussed, and it's yet another of those trade-offs that make it tough to say which is better. An f/2.8-sensitive sensor line has a wider baseline, meaning it can achieve a more accurate focus than a sensor with an f/4 baseline (but of course, the f/4 sensor works with more lenses).


With an f/2.8 lens, the 1D IV has 39 very accurate f/2.8-sensitive cross-type points, with the center one as high-precision. With the same f/2.8 lens on a 1D X, you have 5 even more accurate f/2.8 dual cross-type points, all of them high-precision, but 20 slightly less accurate f/4-sensitive cross-type points, and 16 slightly even less accurate f/5.6 cross type points. Also, on the 1D IV the f/2.8 points are spread across the frame, while on the 1D X the most accurate points are right in the middle. IMO, that means with an f/2.8 lens, the 1D IV is the winner - 39 spread out highly accurate cross-type points vs. 41 less spread out and mostly less accurate cross-type points.


With an f/4 lens, the 1D IV has just one cross-type point, although it operates at high precision. That same lens on a 1D X will have 20 equally accurate f/4-sensitive cross-type points at the sides, and 21 slightly less accurate f/5.6-sensitive cross-type points in the center block, for a total of 41 cross-type points vs. just one. So, the 1D X is the clear winner with an f/4 lens.


Here's where the exceptions on that list of Rick's from the 1D IV manual matter, since you have the 300/2.8 + 1.4x that is one of the exceptions. On the 1D IV, it will behave like an f/2.8 lens, as will the very commonly used 24-105mm and 17-40mm, and based on the criteria above, those lenses will be better on the 1D IV than on the 1D X. I honestly don't know if you'll get more accurate focus when using an exception-list f/4 lens on an f/2.8 sensor, compared to that lens on an f/4 sensor. I suspect not, but it will still be acting as a cross-type sensor - and the cross-type geometry is probably more important in overall performance than the aperture baseline, because in most situations, line orientation determines whether an AF point works at all, vs. subtle difference in accuracy.


So, based on the raw specs of the AF sensors, the lens(s) you have will impact which 1-series AF system is actually better for you (although that will be impacted by the benefit imparted by contributions from the metering sensor, no way to really quantify that). For example, I think you'd be better off with the 1D IV for your 300/2.8 + 1.4x, while Rick would be better off with the 1D X for his 500/4, unless he wanted to use it with the 2x TC, in which case he'd be better off with the 1D IV.


Head spinning yet? Mine is.....

Quote:

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Originally Posted by neuroanatomist

So, based on the raw specs of the AF sensors, the lens(s) you have will impact which 1-series AF system is actually better for you (although that will be impacted by the benefit imparted by contributions from the metering sensor, no way to really quantify that). For example, I think you'd be better off with the 1D IV for your 300/2.8 + 1.4x, while Rick would be better off with the 1D X for his 500/4, unless he wanted to use it with the 2x TC, in which case he'd be better off with the 1D IV.


Head spinning yet? Mine is.....

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I think the gains and losses will be only marginally noticed. But I havedecided that I am not going to pre-order the new 500mm or 600mm, or the 1D X. I am going to wait for the reviews.


Even thoughit only works with the supertele's, thespot focus on the 1D IV is superior to the 7D's IMO. The 1D IV puts the toggle function right at your fingertips on the big lenses, the 7D you had to go in and set the feature. I guess there is the possibility that I could have set a short cut for it, I didn't use the 7D long enough to figure out how.

Quote:

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Originally Posted by neuroanatomist

A common question is, "What does the relative spread of AF points look like?"

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John, Wow, Great info. The way I understood the literature, the 1DX had a wider spread of AF points (I was hoping it would be enough to cover the "rule of thirds" intersections-----another dissapointment)-----By the way, the graphic (and explanation) is outstanding--I have never thought of saving a PS file as a PDF and have it retain the layers. I love this forum:)

Quote:

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Originally Posted by neuroanatomist

So, based on the raw specs of the AF sensors, the lens(s) you have will impact which 1-series AF system is actually better for you (although that will be impacted by the benefit imparted by contributions from the metering sensor, no way to really quantify that). For example, I think you'd be better off with the 1D IV for your 300/2.8 + 1.4x, while Rick would be better off with the 1D X for his 500/4, unless he wanted to use it with the 2x TC, in which case he'd be better off with the 1D IV.


Head spinning yet? Mine is.....

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Sounds good to me, thanks!


Yes, you had my head spinning at "Reply."


-Rich

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Originally Posted by neuroanatomist

I'm curious as to why the macro lenses take such a big hit on AF point activation.

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It's rare for me to enter a discussion on technical matters for fear of embarrassing myself, but I think I can help with this. At macro distances, the effective focal length of a macro lens increases, so the effective f number also increases. The following tables show the effective f number for different magnifications for two of Canon's macro lenses. I suspect that this has something to do with the limitation on AF point activation.

EF 180mm f/3.5L Macro USM

Magnification	1:10	1:5	1:3	1:2	1:1.5	1:1.2	1:1
Effective f/No.	3.8	4.0	4.3	4.7	5.0	5.4	5.8

EF 100mm f/2.8L Macro IS USM

Magnification	1:5	1:3	1:2	1:1.5	1:1
Effective f/No.	3.6	4.1	4.6	5.0	5.9