Archive 2012 · FX AF point coverage....

NathanHamler
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p.1 #1 · p.1 #1 · FX AF point coverage....

So why is it that both Canon and Nikon wont move outside AF points closer to the edge of the frame on their full frame cameras?? The only thing i can think is that AF points closer to the edges would actually perform worse due to decreased sharpness at the edges of the frame...

This is one of the MAIN issues with why i haven't gone full frame (at least i tell myself that), b/c i LIKE using the outside points, and the coverage SUCKS on the Nikon FX offerings...who needs 51 points all in the same place....i like that my d300 and d7000 basically go all the way to the edge....

Any thoughts??

Aug 07, 2012 at 03:41 PM

Tommy_D
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p.1 #2 · p.1 #2 · FX AF point coverage....

There are probably a number of factors that come in to play. One could be light fall off. Another could be field curvature. A third could be distortion. Basically think of every lens problem that could occur in any lens design from 6mm fisheyes to 1200mm super-telephotos and you probably see why they keep the A/F points in the middle, and why the center point just so happens to always be the most accurate.

Aug 07, 2012 at 05:37 PM

Scott Grant
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p.1 #3 · p.1 #3 · FX AF point coverage....

NathanHamler wrote:
So why is it that both Canon and Nikon wont move outside AF points closer to the edge of the frame on their full frame cameras?? The only thing i can think is that AF points closer to the edges would actually perform worse due to decreased sharpness at the edges of the frame...

This is one of the MAIN issues with why i haven't gone full frame (at least i tell myself that), b/c i LIKE using the outside points, and the coverage SUCKS on the Nikon FX offerings...who needs 51 points all in the same place....i like that my...Show more →

Yeah man! I think that is a crazy reason not to shoot FX!

Aug 07, 2012 at 05:43 PM

tobicus
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p.1 #4 · p.1 #4 · FX AF point coverage....

I agree that it would be nice to have wider coverage, but there are lots of folks who shoot full frame and just use focus & recompose anyway.

Aug 07, 2012 at 06:25 PM

Jammy Straub
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p.1 #5 · p.1 #5 · FX AF point coverage....

There's a detailed explanation about 2/3 of the way down this page:

http://www.the-digital-picture.com/Photography-Tips/Canon-EOS-DSLR-Autofocus-Explained.aspx

Aug 07, 2012 at 07:04 PM

hidden_Markov
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p.1 #6 · p.1 #6 · FX AF point coverage....

NathanHamler wrote:
who needs 51 points all in the same place

people who do action photography and like fx over dx. racing pics be real fun otherwise. Most recommendations I have read and applied say crank up the point count. Your subject not exaclty sitting still posed for portraiture and you can run minimal point focus on say an eye.

Article above recommends live view as it bypasses this. So will MF glass, you pick what is in focus and can blow off the red box if you so desire.

Lens' no longer follow strict classic build design of heavy center focus favoritism but until an egghead devises some new optical recipe chances are you won't be getting
this for a while. Then you'd have to wait for sensor makers stopping rubber stamping the same designs with tweaks like pixel count and such. Even these tweaks cost money. Recent heads up thread from a camera tech was nice enough to post d800 sensor replacement price, not a very pretty price lol.

Aug 07, 2012 at 07:58 PM

NathanHamler
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p.1 #7 · p.1 #7 · FX AF point coverage....

Jammy Straub wrote:
There's a detailed explanation about 2/3 of the way down this page:

http://www.the-digital-picture.com/Photography-Tips/Canon-EOS-DSLR-Autofocus-Explained.aspx

hmm, that's interesting...the 1Dx has the best coverage out to the edges (well, as close as you can get...)...i'm wondering how that compares to FX nikon...

as for whatever someone else said about needing all points to shoot auto racing....i've never heard of a sports photographer shooting higher than the 21 point dynamic, which most people agree doesn't react as quickly as 9 point dynamic, which doesn't react as quickly as a single AF point....the more points, the more time it takes the camera's AF processor to figure out what's going on...sure, it's easier to control and stay on the subject, but the AF performance decreases.......anyway, my original point was that even sometimes on DX i find that i could use AF points closer to the edges, so on FX i think there's really no way i'd be happy....

I used to focus and recompose, but i find that i miss shots that way...not really miss the moment, but miss focus...say you focus and recompose, then you grab a followup shot, well that 2nd shot is going to focus on the background, unless you go back a focus on the subject again....that is unless you use the AF on button, and do the whole "press, release, then recompose" bit....which is just one more step....plus if your subject moves, you gotta do the whole process over again.......that's why i'm starting to love the outside points more...put them where the subject is, or where you want the composition to fall, shoot in AF-C, works very, very well for me lately...only time i cant use it is in a DARK wedding reception, when i'm using AF assist on my flash...gotta shoot AF-S, Center point only for that stuff...

Aug 07, 2012 at 11:55 PM

hjanssen
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p.1 #8 · p.1 #8 · FX AF point coverage....

NathanHamler wrote:
So why is it that both Canon and Nikon wont move outside AF points closer to the edge of the frame on their full frame cameras??
NathanHamler wrote:
Any thoughts??

I think the seize of the piggy back mirror will be the limitting factor.

Aug 08, 2012 at 03:34 AM


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