1dmkiii ......... CF autofocus points?

[chazza]

Am getting confused with the custom functions for the AF points .... if I want to capture a fast moving object, what is the best setting inner 9, outer 9 all nineteen .....etc etc and also the AF tracking ..... Help?? :bonk:
Thanks

 

[dinners]

Not sure how it differs from the 1D Mark 2 but for stuff like birds in flight - I just select 1 of the 45 points (usually centre) then set it to 'expand' so the points imediately around it pick up near misses. Then I use AI Servo.

200mm or longer
In one shot mode - assist 'circle' of 6 adjacent AF points around the chosen AF point
In AI Servo mode - assist 'oval' of 12 adjacent AF points around the chosen AF point

Less than 200mm
In one shot mode - AF point does not expand automatically
In AI Servo mode - assist 'circle' of 6 adjacent AF points around the chosen AF point

 

[martyp]

I set the Custom Function to allow me to use the joystick control to select all of them. Depending where the object is in the viewfinder (after composing) will determine the best AF point to select, although if you aren't using fast glass (at least f/2.8) the centre point may be a better choice.

AF Tracking sensitivty I just left it in the middle (default).

This rather long winded video by Peter Gregg explains setting the entire camera up in depth.

Hope that helps?

 

[tdodd]

Am getting confused with the custom functions for the AF points .... if I want to capture a fast moving object, what is the best setting inner 9, outer 9 all nineteen .....etc etc and also the AF tracking ..... Help?? :bonk:
Thanks

It's not a straightforward answer. What sort of subject? How large in the frame? How easy to track accurately with a selected focus point? Moving how fast? How predictably? Towards the camera, away from or across the field of view? How clearly distinguishable is the subject from the background? Are we talking BIF against a blue sky? Dark BIF against woodland or water? Dogs? Cars? Athletes? How much contrast.

There is a a lot to consider. What I would say is that the fewer points you can manage with the easier it will be for the camera to perform. The more points you have active, whether using expansion or ring of fire, the more data the camera has to gather, process and decide upon. It slows down the AF performance and can lead to focus on the wrong thing.

I've been having great success recently shooting a running dog with my 7D, using just a single focus point. I know that if I bring more points into play my success rate will probably decrease. If shooting BIF against a clear background then I can afford to expand the points used because there is little chance of the camera ending up focusing on the wrong thing.

Here's an example from yesterday using the 7D and just a single focus point, no edits....

100% crop, no edits....

Whether using my 7D or 1D3 I always try to use as few points as I can while still keeping an active point over the subject. For things like swifts and other tricky subjects I will use expansion. I've rarely felt that having all points active (ring of fire) was a solution I needed. As for inner 9 vs outer 9 vs all points available, that won't affect the performane of the AF, only which points you are able to choose as active. I keep all 19 available so that I can focus and compose with as much precision as possible. You can't focus/recompose when shooting action, so why limit your options?

Here is the AF point placement for that shot yesterday. No need for AF point expansion....

Here's one from the 1D3 using a single focus point only.....

Canon has published guidance on setting up the 1D3 AF for different shooting scenarios. I have a downloaded copy, but I'm sure a Google will turn up online versions. There are a couple, I think. Here's one....

http://www.usa.canon.com/dlc/controller?act=GetArticleAct&articleID=2866&fromTips=1

another - http://www.wildlifeimagesbyles.net/Technique/1DIII_guide/1diii_guide.html


p.s. IMHO using back button AF is the way to go. It gives you more control if/when the subject escapes your chosen focus point(s).

 

[chazza]

Thanks for all of your comments ......... will keep experimenting I think