5d3 AF hit rate

So I just shot another wedding, and I'm starting to get frustrated with the 5dIII AF. I feel I should be getting a better hit rate. I use BBAF on both the body and my non-OEM battery grip. I keep the camera in AI Servo and have an equally high miss rate when tracking a moving person as opposed to focus and recompose. I'm not trying to focus and recompose on a moving subject. When I focus and recompose I'm hitting the eye, then releasing the AF-On button, recomposing, and hitting the shutter. I only use the cross-type AF points. Shutter speeds equal to or greater than reciprocal focal length rule. Seems to be happening with a variety of even fast lenses: 50mm f/1.2L, 70-200mm f/2.8 II, etc. In the AF Config screen, I'm using Case 1. For sensitivity for both the first shot and second shots I have it set in the middle between |- release - and - focus -| I hope that should cover all the diagnostic questions--I don't think my technique sucks.

It seems as though the AF design of the 1dx and the 5dIII are the same? Getting a case of GAS?

Silver-Halide wrote in post #18062787
So I just shot another wedding, and I'm starting to get frustrated with the 5dIII AF. I feel I should be getting a better hit rate. I use BBAF on both the body and my non-OEM battery grip. I keep the camera in AI Servo and have an equally high miss rate when tracking a moving person as opposed to focus and recompose. I'm not trying to focus and recompose on a moving subject. When I focus and recompose I'm hitting the eye, then releasing the AF-On button, recomposing, and hitting the shutter. I only use the cross-type AF points. Shutter speeds equal to or greater than reciprocal focal length rule. Seems to be happening with a variety of even fast lenses: 50mm f/1.2L, 70-200mm f/2.8 II, etc. In the AF Config screen, I'm using Case 1. For sensitivity for both the first shot and second shots I have it set in the middle between |- release - and - focus -| I hope that should cover all the diagnostic questions--I don't think my technique sucks.

It seems as though the AF design of the 1dx and the 5dIII are the same? Getting a case of GAS?

I know people poo poo AI focus but I run my 5DIII on that pretty much all the time regardless of if Im shooting moving or still subject usually on case 2, I have a very good in focus rate, Id say at least 97%

Plus one for a change to ai focus. If the light was particularly bad I would also defocus for each shot as it seemed the further the lens had to focus the more accurately it acquired. I would try using a focus point closer to the area you want to focus on rather than focus and recompose.

I used my 5D3 with the 70-200 2.8 during NBA seasons, and AF was good enough to track players. I think I used case 4 though. I am sure the 5D3 is adequate for wedding action shots if basketball posed no real issues. If you are having issues with all lenses (I wouldn't think the 50L is a good test mule for a good AF system though, but the 70-200 should be), then perhaps try resetting everything and resetting them, or send it in for a once-over.

Agreed that AI Focus is the best of both worlds. Not to mention worry-free.

Silver-Halide wrote in post #18062787
So I just shot another wedding, and I'm starting to get frustrated with the 5dIII AF. I feel I should be getting a better hit rate. I use BBAF on both the body and my non-OEM battery grip. I keep the camera in AI Servo and have an equally high miss rate when tracking a moving person as opposed to focus and recompose. I'm not trying to focus and recompose on a moving subject. When I focus and recompose I'm hitting the eye, then releasing the AF-On button, recomposing, and hitting the shutter. I only use the cross-type AF points. Shutter speeds equal to or greater than reciprocal focal length rule. Seems to be happening with a variety of even fast lenses: 50mm f/1.2L, 70-200mm f/2.8 II, etc. In the AF Config screen, I'm using Case 1. For sensitivity for both the first shot and second shots I have it set in the middle between |- release - and - focus -| I hope that should cover all the diagnostic questions--I don't think my technique sucks.

It seems as though the AF design of the 1dx and the 5dIII are the same? Getting a case of GAS?

You say you are using the AF-ON button to BBF; you did disable focusing from the shutter button first didn't you?

john crossley wrote in post #18064101
You say you are using the AF-ON button to BBF; you did disable focusing from the shutter button first didn't you?

Yes, thank you. Great question.

Missing from your initial description is information about what apertures you're shooting at, and how much you're recomposing. With fast lenses, it certainly matters. Also, what is the lighting like, bright, dim, colored? I ask because I've noticed that when shooting with my 85L, it is sometimes tricked in very low light and strongly-colored lighting situations (e.g. club with blacklights). It will appear to find and lock focus normally, but it's consistently off. The 100/2.8L on the other hand nails focus in the same situations. In bright light, the 85L has no such issues.

Also, if you're shooting wide apertures like f/1.8 or wider, there is no such thing as a "non-moving subject" unless you're actually using a tripod and shooting a still life. If you're handholding the camera and shooting people, any time recomposing or between button presses allows for critical focus to be lost after AF lock. And of course recomposing itself could be an issue, and not just at the widest apertures depending on subject distance, focal length, etc.

absplastic wrote in post #18065168
Missing from your initial description is information about what apertures you're shooting at, and how much you're recomposing. With fast lenses, it certainly matters. Also, what is the lighting like, bright, dim, colored? I ask because I've noticed that when shooting with my 85L, it is sometimes tricked in very low light and strongly-colored lighting situations (e.g. club with blacklights). It will appear to find and lock focus normally, but it's consistently off. The 100/2.8L on the other hand nails focus in the same situations. In bright light, the 85L has no such issues.

Yes, thanks. I know that if I'm shooting at f/1.2 and focusing half a meter away, that a large arc of focus-and-recompose will put an eye out of the depth of field. That's largely not my expectation and I DO look at the depth of field charts for the wider apertures I often, but not always, shoot at.

I'm not sure what you mean here, could you maybe try explaining this another way? Thanks.

He means that at such narrow apertures any delay between focus and shoot is enough for your stationary child to twitch or your hand move fractionally thus moving the paper thin DoF and throwing the intended area of focus off, so you get a nose instead of an eye.

I've been pleased with my 5D III AF, and I've shot everything from portraits and weddings to sports (soccer and softball) with it. I haven't had any consistent issue with out of focus shots except when used in low light with AF-assist and non-Canon (YN) flashes. A switch to an OEM Canon flash solved that.

Lyndön wrote in post #18065602
I've been pleased with my 5D III AF, and I've shot everything from portraits and weddings to sports (soccer and softball) with it. I haven't had any consistent issue with out of focus shots except when used in low light with AF-assist and non-Canon (YN) flashes. A switch to an OEM Canon flash solved that.

Ditto, It mine has been a rock solid performer.

Silver-Halide wrote in post #18065535
Yes, thanks. I know that if I'm shooting at f/1.2 and focusing half a meter away, that a large arc of focus-and-recompose will put an eye out of the depth of field.

Shooting at f/1.2 from a half meter away and your motion from breathing can put the eye out of focus, it does not take a large arc or recomposing. Even just moving the AF point from the eye to between the eyes can lose focus, especially when considering also the moving subject issue:

absplastic wrote:
Also, if you're shooting wide apertures like f/1.8 or wider, there is no such thing as a "non-moving subject" unless you're actually using a tripod and shooting a still life. If you're handholding the camera and shooting people, any time recomposing or between button presses allows for critical focus to be lost after AF lock. And of course recomposing itself could be an issue, and not just at the widest apertures depending on subject distance, focal length, etc.

Silver-Halide wrote in post #18065535
I'm not sure what you mean here, could you maybe try explaining this another way? Thanks.

I mean that people move slightly and continuously, even when they are standing "still", including both photographer and subject. Depth of field at f/1.2 or f/1.4 can be a few millimeters in a 1:1 crop or large print. Between the time you lock focus, and the fraction of a second later when you release the shutter, either the photographer or the subject could move or sway enough for something other than what was focused on to be in focus--bangs or eyebrows instead of irises of the eyes, for example.