1D Mk.III C.Fn III-2 Misconceptions

There seems to be a misconception among some users about Custum Function III-2. I have seen it a few times here and I have been seeing alot in other forums.

So I thought I would post this to try and address the misconception. Also NOTE that I am not drawing any relationships between this and the Focus issues some are having with the camera.

C.Fn III-2 is used to set the AI tracking sensitivity and the set up for the function seems to be causing some confusion.

When you set this CF up you have Slow, Moderatley slow, 0 or normal, Moderatley fast and fast.

Some people believe that if they are shooting Fast moving subjects that this should be set to fast.

NOT TRUE.

This CF determines how fast the focus will change to a differant subject or focal point if something enters the view in front of or behind the subject.

So if you are tracking a Bird and have the CF set to fast the moment something passes in front of the bird or you move the focusing point of the subject the camera will refocus on the new object in the focal point.

If you want the camera to ignore things blocking you target while tracking it is better to set this CF to SLOW.

Fast would be used if you are wanting to use AI Servo to shoot mulitple subjects and what the camera to refocus everytime you move the Focal point to a new subject.

Here is a quite directly from the Canon Professional Network.

The heightened sensitivity of the EOS-1D Mark III AF system can, in some situations, cause the autofocus to appear erratic. In fact, it is not erratic at all, simply it is so sensitive that it will identify and re-focus on a new subject much faster than previous cameras – and crucially – much faster than you might expect.
Turning down this response rate to ‘Moderately Slow’ or ‘Slow’ will help when tracking subjects as the camera will not jump instantly to any new ‘subject’ or the background and should ensure a more familiar AF response. Note that this will not slow down the speed of the autofocus, only the speed at which the camera recognises a new subject. It’s like a buffer than provides you with more time and leeway to track a subject without the camera constantly finding new ones.

Hopefully this will help dispell the misconception, and help some people that may have set this Cf incorrectly and have been having problems.

But if you have it set on Slow following a BIF then lose it (so focus lock on something else ) you dont have a chance of getting back onto it .as its to slow
IF set to fast you do have a chance as long as you can pick the BIF up again as you can reaquire focus on FAST but not on SLOW
Not looking to argue here but just the way i see it and have tested this too
Rob.

GyRob wrote in post #3979371
But if you have it set on Slow following a BIF then lose it (so focus lock on something else ) you dont have a chance of getting back onto it .as its to slow
IF set to fast you do have a chance as long as you can pick the BIF up again as you can reaquire focus on FAST but not on SLOW
Not looking to argue here but just the way i see it and have tested this too
Rob.

I've been shooting BIF on slow with pretty good results since firmware 1.10. When you lose focus you pump the focus button again. Like wilvoeka said, there is no difference in the speed the camera acqiures focus when you push the button. On the fast setting I just don't have the physical capability to hold it on a bird unless it's filling the whole frame. This is a change in technique from my 1D2.

GyRob wrote in post #3979371
But if you have it set on Slow following a BIF then lose it (so focus lock on something else ) you dont have a chance of getting back onto it .as its to slow
IF set to fast you do have a chance as long as you can pick the BIF up again as you can reaquire focus on FAST but not on SLOW
Not looking to argue here but just the way i see it and have tested this too
Rob.

And by the same token, you can just as quickly lose focus, too. It's all about compromises and what you're willing to live with.

bgmoore wrote in post #3979559
I've been shooting BIF on slow with pretty good results since firmware 1.10. When you lose focus you pump the focus button again. Like wilvoeka said, there is no difference in the speed the camera acqiures focus when you push the button. On the fast setting I just don't have the physical capability to hold it on a bird unless it's filling the whole frame. This is a change in technique from my 1D2.

What worries me with setting to SLOW if you don't pump the AF and you slightly loose track of the BIF or subject you have to rely on the MKIII's predictive focus mechanism to work out where the BIF is, so if the BIF accelerates when loosing track of the BIF the camera will fire and BIF will be OOF. Maybe because you pump the AF that is why you are having success with BIF type shots at LOW setting?

Can't remember who told me but a Canon guy said "the high sensitivity setting will overide the predictive focus" which he did not recommend. I tried this setting with success at a Motorcycle Race meeting last weekend, I also have had success with the MID setting.

Can the MKIII Predictive Focus Mechanism work out where an accelerating object will be. Anyone know the answer?Cheers

PacAce wrote in post #3979742
And by the same token, you can just as quickly lose focus, too. It's all about compromises and what you're willing to live with.

Yes i do except that but surly thats were the skill of the photographer will come into it by making sure he/she keeps the focus point on the bird/subject -or if its lost quickly getting back onto it .

on FAST he/she has a chance on SLOW they dont.
this is more for the faster flying birds dove/pidion/duck's.
For Herons / Egrett's Swans slow could be used with sucess as well but i would still stay on fast.
Rob

GyRob wrote in post #3979915
Yes i do except that but surly thats were the skill of the photographer will come into it by making sure he/she keeps the focus point on the bird/subject -or if its lost quickly getting back onto it .

on FAST he/she has a chance on SLOW they dont.
this is more for the faster flying birds dove/pidion/duck's.
For Herons / Egrett's Swans slow could be used with sucess as well but i would still stay on fast.
Rob

Rob, I agree with you on this one, not that I am that skilled nailing the focus point on the subject especially the eye of a bird

Cheers

Why don't people try all the variations and then set to what suits you in the situation you are shooting in?

If you have tried, then people post there findings and see if you all find common ground

MaDProFF wrote in post #3983520
Why don't people try all the variations and then set to what suits you in the situation you are shooting in?

If you have tried, then people post there findings and see if you all find common ground

Most of the settings i use are indeed from what others who got the MK3 early have tried and found to be OK .
the problem is we all shoot diffrent subjects so my setting's for birds may not suit someone who shoots sport.
And even then some find a setting works well for them but other's maybe dont like the way it makes the camera react .
For me i want it to not only work as fast as poiseble but have it feel that way too - but im sure others would find My settings make the camera to lively and almost jerky/ twitchy .
Rob.