Focussing issue with 5D Mark III

[crockny]

I am using my relatively new 5D Mark III with my old 400mm 5.6 lens for bird photography.  It often will not grab focus.  I have to manually focus closer before it focuses.  It doesn't seem to matter which distance setting I use on the lens.

So I am missing quite a few bird shots.  I have no problem when using my old 7D.

I don't know if this is a full-frame issue, my particular copy of the camera issue, the combination of lens and camera, or something in my setup, even though I followed an online tutorial for setting up the 5D Mark III for bird photography.

Anyone have experience with this issue?

[crockny]

1.  I never had this issue with the 7D so I don't think it's the lens.  But you are right - the focusing options are beyond belief on the 5D ... that's why I followed a birding tutorial when setting them.

2.  I use the center focus single spot except when close to a bird when I move the single spot around..

3.  I did have the "lens drive when autofocus impossible" set to "off".  I remember I had it on "on" but was getting blurry shots ... apparently you can't win ... !

[crockny]

Not sure what you mean by the 5.6 focus points...
No teleconverter - it wouldn't work with this lens.

[crockny]

I most often have the issue when focusing on something small in the distance ...

[kvbarkley]

From the online specs:

"61-point (up to 41 cross-type points)
* One to five cross-type AF points at f/2.8, 10 to 20 cross-type AF points at f/4, and 15 to 21 cross-type AF points at f/5.6. (The number of cross-type AF points will differ depending on the lens.) "

[crockny]

Interesting - I did try auto and had no problem going from a "close" subject to "far" and vice versa. But in manual with my settings I had to "nudge" them both ...

[crockny]

It may be as simple as that ... I did the same experiment twice on static subjects and had trouble with my regular settings but not when I switched the "lens drive when AF impossible" to ON ... go figure. I know I changed this setting for a reason ... probably too much "hunting" at some point ...

[Waddizzle]

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@crockny wrote:
It may be as simple as that ... I did the same experiment twice on static subjects and had trouble with my regular settings but not when I switched the "lens drive when AF impossible" to ON ... go figure. I know I changed this setting for a reason ... probably too much "hunting" at some point ...

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I hear ya about the too much hunting.  Exactly why I have it turned OFF.  I use the center point for focusing, with assist points when I use AI Servo.

BTW, I think your 400 f/5.6 can tolerate a 1.4x extender on a 5D3, provided you use the center AF point.  AF points have set upper limits on f/stop that they can still focus.  Some high end cameras can go to f/8.

[Waddizzle]

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@ebiggs1 wrote:

"Changing batteries takes time ..."

That's why most folks do it at home 'after' the shoot.  Not during the shoot.  Must be a trick to charge your battery in the field shooting a BIF.  You have my permission, nudge away!

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Yup, I do it at home.  But, some guy just told me to do change them in the field.

[diverhank]

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@Waddizzle wrote:

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@crockny wrote:
It may be as simple as that ... I did the same experiment twice on static subjects and had trouble with my regular settings but not when I switched the "lens drive when AF impossible" to ON ... go figure. I know I changed this setting for a reason ... probably too much "hunting" at some point ...

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I hear ya about the too much hunting.  Exactly why I have it turned OFF.  I use the center point for focusing, with assist points when I use AI Servo.

BTW, I think your 400 f/5.6 can tolerate a 1.4x extender on a 5D3, provided you use the center AF point.  AF points have set upper limits on f/stop that they can still focus.  Some high end cameras can go to f/8.

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Turning this option on does not affect hunting at all in my experience. This option is designed for larger lenses not the 400/5.6. Even for the 600 f/4, it never hunts. Personally that option is out dated, designed for old super teles. All it does now is stalling your focusing

[RobertTheFat]

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@Waddizzle wrote:

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@ebiggs1 wrote:

"... not when the difference is make or break getting a once in a season shot."

And who gives a ---- about battery life.  Take two batteries for pete's sake.  

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Changing batteries takes time, too.    More time than nudging the lens. 

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I'm not a fan of battery grips; but that, after all, is what they're for.