Problem focusing in falling snow

I have a Mark III and was out the other day photographing Elk in the snow.

The snow was not heavy, but it definitely was snowing and accumulating on the ground.

My problem was the camera would search back and forth many times before finally locking focus on to the elk, sometimes I would have to start over.

There were other photographers with a Nikon D2X, and Canon 20D etc. being used also, and they did not experience this behavior.

I had the most expensive camera there, and had the most difficulty focusing on the elk when I wanted to.

I was shooting on one shot mode while using the center focus point, I also disabled the surrounding points.

Has anyone experienced the same thing, especially with the Mark III?

Perhaps I need to change one of the custom focus settings under situations like this. I don't like the idea of having to change custom functions out in the field for different circumstances.

Any suggestions would be appreciated

PS: on another note I am now growing impatient with Canon's lack of acknowedgment and or fixing the Mark III focusing issues.

It actually sounds as though the focusing system on the MIII is either too good or too sensitive.

I agree the focus is too sensitive, but if it impedes me to take the shot I can't say that it is too good.

Perhaps with adjustment it will be good, but not now.

How much light was there? (f-stop, speed, iso..) What lens?
In a storm, I'm guessing not much light. Lens speed matters a lot here too. Add heavy snow to the mix, and I wouldn't expect a quick focus. You might want to manually focus in such a situation. I find it pretty easy with the III's bright view finder. Or, if you're on a tripod, try the live view. Very easy to manually focus, 1x, 5x or 10x.

JohnC

What lens was being used?

I was using the Canon 300 f4 L IS with canons 1.4 teleconvertor.

I don't have shooting data with me at present.

It still should do as good as the other cameras, shouldn't it?

You were shooting with an f/5.6 lens, which might be the problem. Do you know what the others, not having problems, were shooting? Did you try it without the TC? That extra stop may have helped a lot.

JohnC

Try using manual settings for focus. Then the camera will not have to "hunt".

I agree with several posters - use manual focus when the camera cannot figure out the target to focus on.

SkipD wrote in post #4044469
I agree with several posters - use manual focus when the camera cannot figure out the target to focus on.

Its hard to say what was happening.

However, please dont assume just because you have the most expensive body, youll be free of problems or do better than other people.

That being said, do you know that you had the most expensive glass? Youre shooting at f/5.6. They could have been at f/4 or f/2.8. That would aid in focusing a great deal if it was low light to begin with.

Perhaps the MkIII is just too sensitive and is able to pick out the snow while their cameras cannot. Its just simply impossible to definitely say what youre problem is without actually being there and seeing what was going on and what lenses they were shooting problem-free with.

I did try to use manual focus, but I guess I am a bit inept at it, especially on moving targets.

The lenses that were being used were the Nikon 600 with a 1.4 I believe. Outside of that the lenses were mostly the 75-300, oh yeh one lady did have the Canon 100-400.

I believe most if not all of these when extended, as they would have been in this case are in fact a 5.6 aperature for focusing.

I just have never had this issue before, and am wondering if a function setting might help it.

If I have the chance to shoot in the snow again, perhaps I can play with settings to see if anything helps

one other question, did you try ring of fire on oneshot? the af points on the 1dmkiii are much, much smaller than either the 20d or nikon, which can lead o hunting if you don't know how to deal with that smaller af point (note that the af point and af display do not overlap 100% in any camera)

I have had rain and falling snow ruin my idea of AF on my 20D and my 40D. Time to use MF.

outdoorphoto.ca wrote in post #4045136
I did try to use manual focus, but I guess I am a bit inept at it, especially on moving targets.

The lenses that were being used were the Nikon 600 with a 1.4 I believe. Outside of that the lenses were mostly the 75-300, oh yeh one lady did have the Canon 100-400.

I believe most if not all of these when extended, as they would have been in this case are in fact a 5.6 aperature for focusing.

I just have never had this issue before, and am wondering if a function setting might help it.

If I have the chance to shoot in the snow again, perhaps I can play with settings to see if anything helps

Well then all I can say is that, AFAIK, all the CFn's that refer to AF on the MkIII have to do with maintaining focus in servo mode...Not actually acquiring focus to begin with.

Except for the focus pt expansion ( which I use ). However, I dont know if this would help you since Ive never shot in snow...

When I get a situation like that where the lens cannot figure out what to stop and focus on I just switch the darn thing off and go manual. No big deal, just somethings are harder for the electronics to overcome.