Using a 1V (same AF system more or less) I only use multiple points when tracking fast moving objects and I am having trouble keeping a single point over the object. This is still a little hit-and-miss, but better then a single point.

For landscape you should be choosing your focus point carefull; one point is more then enough.

Curiosly in my 1Ds the next to the center points are more accurate. I did some tests by shooting a newspaper taped on a wall from an angle at maximum aperture and the center point had a very small error margin. The neighboring points were right on. It does´nt even make a difference in real world shooting.

Thanks a lot for your thoughts, Paul, Francois and Sergio !

Seems that these 45-points AF are not so much used on 1v and 1Ds, and if I have well understand you use this feature on moving subjects instead as the AI Focus ?
Unfortunaly, I'm not so confident with my eyes for using the manual focus, but I will soon try the advice about the not so well delimited subjects with the 45-AF points!
Thanks for your help !

JF

I find that for 90% of my shooting, the 45-point AF delivers acceptable to excellent results. I use one-shot for still subjects and AI servo for moving ones. I use the center point when I want to make sure the camera focuses on what I want it to focus on, like a bird visible through a small opening in the foliage of a tree, or picking out one particular face in a crowd, etc.

JF,
One thing you can do is to test with different AF settings. Be sure to use always the same testing pattern (AF-45 point, AF-1 point, Manual Focus - for example). Test on different subjects and then draw your conclusions. I guess you'll soon learn what works for specific situations.

Francois

I usualy shoot lanscapes on focusing only with the center AF point and then I recompose before shooting,
the user manual tell me that this center point is a lot more accuracy, the automatic 45-points AF seems to be an powerful feature of this camera, but in witch situation are you using it ?

JF

I use the 45-point AF with distant, not so well defined, subjects.  For example, but not limited to, distant foliage.

I always check if my subject is in focus and do not hesitate to fine-tune with manual focus.

As Paul mentionned, I use the 45-point AF with moving targets.

On other occasions, I use the AF system with one point (either central or lateral).
An example for one-point AF is with wildlife. In this case I like to focus on the eye of the animal (if possible). The central point is the most accurate.

Don't forget that in some AF modes the exposure is linked to the selected point (or group of points).

Hope this helps,
Francois

Actually I didn't make any real test. More of the real world stuff than a formal testing session.

Have fun,

Francois

I find Canon autofocus very reliable and one of the great advantages of having switched from MF to the 1Ds is autofocus. My productivity boosted three fold. Suddenly realized how much time I spent focusing!

Just to make things clear... I use AI Servo mode on moving subjects.

On static subjects, I use the One Shot mode with either 45-point AF or 1-point AF. Also, note that some lens combinations only work with your central AF point. For example, the EF 100-400 IS Zoom + 1.4 extender will only AF on the central AF point (this example is valid only for EOS-1/3 serie cameras)

I think Jonathan has given good examples...

You will find that the 45-point AF is quite reliable.

Francois

Thanks again !
After reading your new advices and those from Jonathan, I can tell you that the next session will be with the 45-AF point on, it clearly seems that I must try this feature !
I owned a D60 with a very problematic AF, a 10D with a good AF, those with the 1Ds should be perfect
Greetings !

JF

Ok, I will do it, Francois !
thanks for your help.

JF