5d3 slow to react/respond autofocus AF

Hi gang!

Was out shooting at a wedding this past weekend. Was a bright sunny day so plenty of light. Shooting with my 70-200 f4 IS and on numerous occasions, when using autofocus (I use back button) the camera doesn't respond until like (what feels like) 1 second. It's like so slow that I wonder whether I pressed it properly. After the lag, then the focusing kicks in and locks on. I've seen this with other lenses I have. On other cameras I've had, if contrast is bad then it will just hunt but AF starts hunting right away.

Configured to single AF point using one shot mode.

Suggestions?

I'd start by putting AF back on the shutter and seeing whether there is a delay using the shutter to trigger AF. If there is no lag with the shutter button, that would suggest a problem with the back button. The fact that it is a regular lag rather than an intermittent failure suggests to me that this is not the problem, but it is something you can test, and either confirm or rule out, in a matter of a minute or two.

paddler4 wrote in post #17132224
I'd start by putting AF back on the shutter and seeing whether there is a delay using the shutter to trigger AF. If there is no lag with the shutter button, that would suggest a problem with the back button. The fact that it is a regular lag rather than an intermittent failure suggests to me that this is not the problem, but it is something you can test, and either confirm or rule out, in a matter of a minute or two.

good suggestion thanks. perhaps its mechanical.

Was the IS on or off? I'm wondering if that might make a difference.

LV Moose wrote in post #17132259
Was the IS on or off? I'm wondering if that might make a difference.

It was on in this case, but i've seen it happen on other lenses like 85mm f/1.8 or 35mm f/1.4 which don't have IS.

Hmm. I haven't seen this on my 5DIII, but don't use back-button focus. You said "bright sunny day,"...Were you by any chance shooting toward the sun? (I don't mean directly into it).

LV Moose wrote in post #17132273
Hmm. I haven't seen this on my 5DIII, but don't use back-button focus. You said "bright sunny day,"...Were you by any chance shooting toward the sun?

Not directly, but it was in my general direction. However, on other lenses, this happened indoors.

Well, good luck. I imagine it's irritating.

Were you using the center point or one of the others? Some of the others are not cross type points, so they can take longer to focus.

I probably wasn't using centre very often. Until the 5D3, I always used centre/recompose. Since getting the 5d3, I've tried to avoid that and purposely use just the cross type only setting and move the point around quickly to the approximate location. If I'm still off I'll recompose.

Regardless of shooting conditions, the camera should at least attempt to focus immediately. It may fail, but it should try as soon as you press the button.
Don't forget that you can also assign AF to the * button, if you just want to evaluate another button.

I have had a similar issue with my 1DX - it seems like it struggles to wake up.

Echo63 wrote in post #17133504
I have had a similar issue with my 1DX - it seems like it struggles to wake up.

good point, i'll test/keep an eye out for it when it wakes from sleep mode.