Have soft images? This helped me a ton!

[Robert Welch]

I've been doing some testing with my 5DmkIII, primarily testing various lenses and comparing files vs. a 1DmkIII (that has been pretty reliable with AF) and the same lenses. I can say the 5DmkIII is proving to be the most reliable Canon body I've owned for AF (at least since my EOS 3 camera, but that was film so it was harder to evaluate for critical focus). Anyway, after about 200 shots, I've found 2 photos that were clearly out of focus, just missed it. The rest are either right on, or within a reasonable range that the photo would be entirely usable for most purposes. As compared to my 1DmkIII, which the best I've ever acheived was about 90% accurate, and as bad as about 75% accurate. My 5D original was worse, and my 7D is probably worse, though I've never really tested it since I never use it for really critical photos.

One other thing, the image quality of the 5DmkIII in mRAW mode compares favorably to the 1DmkIII at ISO 200-400 (obviously, the 5DmkIII will be much better at much higher ISOs, so I haven't tested these two at higher ISOs yet). This impresses me, because I've always felt the 1DmkIII has extremely good IQ at those lower ISOs, on a pixel per pixel basis, probably one of the best, maybe?! (I believe Rob Gailbraith has stated as much.) This is very encouraging to me, as I'm going to part with my trusty old 5D, and am now feeling like I'll probably replace my 1DmkIII with a 2nd 5DmkIII body one day (or maybe another body not announced yet?), once I've absorbed the cost of the first one anyway.

BTW, the main lenses I've focused on testing were the 24-70 (first version, of course...a rather good copy, knock on wood) and my trusty 24-105, both were tested wide open. The 24-105 barely beats out the 24-70, but not by a very appreciable difference, and that was on either camera, the 5DmkIII or the 1DmkIII. I was encouraged by this as I can freely use either lens on either camera without worry.

 

[idratherplaytennis]

Did you read the manual?
Apparently the AF points are lens dependent and specified by group.

Specifically:

24-105 F/4 = Group C
24-70 F/2.8 = Group B
70-200 F/2.8 II = Group A
Most primes = Group A

Does this imply we have to adjust the focus style based upon the lens?
That's a major usability issue if true

OK, after re-reading it I think it just tells you what AF points are available with a given lens.
Curious why the 24-105 they bundled as a kit lens does not have the Dual Cross type AF points, which are superior?

ET

I actually have so many +1's or +2's in this thread that I wanted to quote but chose this as I discovered this fact tonight after getting the camera today. I haven't loaded any images yet onto my comp to check the sharpness but something seemed off til I read the manual about the AF mode (coming from a 20D, I have SOOOO much reading to do now, I realize ><) but caught the Spot Focus mode and it seemed to help a bit with the focusing. Sad that the 24-105 is in Group C and not at least B, which I was really hoping for since I central focus almost exclusively but I'll see how things go in time. I do plan to eventually go for a 24-70 2.8 but that's in a few years. Also weird to see is that they didn't list the version II of the lens.. which puzzles me because it was announced before the Mark III (I think...) and so you'd think they would know which category it falls in. Oh well- time will tell. Time to go read me a manual before falling asleep!

 

[Drizzt321]

Did you read the manual?
Apparently the AF points are lens dependent and specified by group.

Specifically:

24-105 F/4 = Group C
24-70 F/2.8 = Group B
70-200 F/2.8 II = Group A
Most primes = Group A

Does this imply we have to adjust the focus style based upon the lens?
That's a major usability issue if true

OK, after re-reading it I think it just tells you what AF points are available with a given lens.
Curious why the 24-105 they bundled as a kit lens does not have the Dual Cross type AF points, which are superior?

ET

I actually have so many +1's or +2's in this thread that I wanted to quote but chose this as I discovered this fact tonight after getting the camera today. I haven't loaded any images yet onto my comp to check the sharpness but something seemed off til I read the manual about the AF mode (coming from a 20D, I have SOOOO much reading to do now, I realize ><) but caught the Spot Focus mode and it seemed to help a bit with the focusing. Sad that the 24-105 is in Group C and not at least B, which I was really hoping for since I central focus almost exclusively but I'll see how things go in time. I do plan to eventually go for a 24-70 2.8 but that's in a few years. Also weird to see is that they didn't list the version II of the lens.. which puzzles me because it was announced before the Mark III (I think...) and so you'd think they would know which category it falls in. Oh well- time will tell. Time to go read me a manual before falling asleep!

The reason the 24-105 is in Group C is that it's f/4 not f/2.8. The dual cross points down the center line require f/2.8 as the as narrowest aperture to work. I believe they become normal cross type points since those operate up to f/5.6 I believe.

Totally agree with everyone else, the number of AF points is astounding, and in my brief usage so far, it usually picks the point(s) that I don't want it to focus on. I'm probably going to be using expanded or surround mode, but I'm going to have to start getting really quick about switching AF point areas because I'm so used to the 5d2 where I only use the center + recompose.

 

[idratherplaytennis]

Thanks for the info! No more f/4's for me!! Good and bad news, hahaha. Bad for the wallet, great for the shots.

 

[Drizzt321]

Thanks for the info! No more f/4's for me!! Good and bad news, hahaha. Bad for the wallet, great for the shots.

Why? You still have all of the normal cross type points, and while the dual-cross are assuredly nice to be able to use, but it's hardly necessary for all shots.

Besides, with so many AF points, I'm expecting I'll start using more off-center point points/expansion for shots. Going to take a lot of practice and effort to break the habit, but on wider apertures (f/2 and below) I'm expecting it'll help me get more usable shots since the plane of focus won't be shifting when I focus with the center, then recompose.

 

[bp]

+1. spot AF on the MK3 is the shizzle rizzle

The MK3 has breathed new life into super wide aperture for me. The 85L II is like a whole new lens. With the 5D2, I'd become so frustrated with constant focus misses, that I rarely shot at 1.2 anymore - even after MA'ing it - it wasn't the MA, the body was just... missing.

Without any MA at all, the MK3 has changed everything. Keeper rate (from focus anyway) has gone from 1 out of 5, to 9 out of 10.

 

[Bosman]

I have never used auto AF. Why would anyone let the camera decide that one? Single point is what i will continue to use and maybe with the 4 assist too since they look like spot af points surrounding as backup. When you have a static subject like portraiture you can use single spot af but the manual recommends or at least i have read this that its not good to use for moving subjects because it is a very finely tuned focus point. I removed the points i wont use from the options when i go to change them. One i removed was zone, if i was shooting animals in the sky thats prob the only time id use that setting. The others were the last two auto focus settings that are full auto. I like that i dont have to scroll thru them. I also made it so my rate button was a 5 or it was nothing since i only want to find my choice images quickly.
Like others I have found the 5dm3 has tamed my beast F1.2 50mm lens. It looked pretty dang good outta the box but i have since tuned it +5 micro-adjustment which is so minuscule but then so is F1.2.