Need Help with Auto-servo Focus on 300 2.8/1D Mark IV

Here is the gear in question

Canon 1D Mark IV - (45 point AF enabled)
Canon 300 2.8 USM (version 1)

Here is the issue

Recently I bought the 300 2.8, prior to that I would shoot sports with a 100-400 5.6. With the 100-400 I set a single auto focus spot on the 1D and would put my action on the spot and get about 90% of my shots in focus.

On the weekend I used my 300 2.8 for the first time for a football game, and the auto focus spot would jump all over the place, grabbing new focus points throughout a play. basically I would have my shot set, press the shutter and get the first couple images in focus, then someone else in frame would steal the focus and the next several shots are OOF. Actually about 50% of my images are now OOF.

I suspect that the 1D deals with a 2.8's fast focus differently and that it doesn't do it with my 5.6.

I tried changing a bunch of my settings, but nothing would stop the auto focus from jumping around in my viewfinder.

Can anyone suggest a solution that can get me back on track.

Thanks
Doug

Doug

I have the same issue with my 7D and this same lense. I have tried changing the focus tracking speed to see if slowing that down will stop this lense from changing when something jumps in front. Still working the kinks out so let me know what you find out.

Thanks
Rob

There are definitely custom focus settings that control that behavior on the 1d4...although I can't think of specific settings off the top of my head since I've been messing around with settings on the 1dx mostly lately. Do you really WANT auto focus points when shooting what you're shooting? Wouldn't center point focusing with some surrounding assist points be better for tracking a player? You can definitely control whether focus stays with the main focus point or switches when something passes in front as well as the speed in which it does that. I'm sure somebody can jump in and tell you exactly what settings to use.

Thanks sdipirro

to clarify, I don't want Auto-Focus points, I want to manually pick one point and have only that one in focus.

I manually set the point I want based on where I want to frame the action. Say the action is traveling left to right, I put my focus point manually over on the left side of center so i get space in front of the action for framing. With my 100-400 this was no problem, the point I picked was the one that always had focus. With the 300 3.8 the point jumps around to surrounding points when anything new comes into frame. I would rather the point not jump to other points at all, and just stay where I set it.

should also note that any other lens i use 70-200 2.8, 24-70 2.8 etc.... holds a single point. it is only the 300 2.8 that jumps around.

Does that make sense?

Rworman wrote in post #15064920
Doug

I have the same issue with my 7D and this same lense. I have tried changing the focus tracking speed to see if slowing that down will stop this lense from changing when something jumps in front. Still working the kinks out so let me know what you find out.

Thanks
Rob

This ^

Although I don't understand why it is jumping to pther points. Double check that you still ahve single point selected and it should stick with that one. The lens shouldn't change that setting at all.

Baffled! I tell my 1D4 what focus point to use ( normally with surrounding AF point assist) and it uses it regardless of which of my lenses I use and where the subject is.
Do you have all AF points enabled/selected? If you do then it will tend to focus on the nearest object - just a thought.