5D focus points ?

Can someone explain the difference between ALL the focus points lighting up in red and just one? When I change the focus point, at one point, they all light up. If I use that setting, will my focus be better? I use AI Servo.

I've found the best focus for me on the 5D is to use Al Servo and then go into custom functions and set it to expanded center circle. I've got mine set up so it only focuses when I hold down the star button as well and when not shooting fast, I'll focus on where I actually want the focus, as in scenics and then let my thumb off the star button and reframe. But I came from a lifetime of shooting film cameras that way so it's pretty natural for me.

I did not have good luck shooting with all the red lights on and using just one around the diamond since it wasn't expanded usually gave me a lot of misses.

Since I've set my camera up this way I've had much better and more consistant results. If others have found better ways please tell, as it's my one big complaint when using the 5D. Most of the time, this method works great but grabbing faster shots it does not and I tend to frame to get the center circle where I want the focus, shoot a little wider and then crop later, not the best way to do things even though the camera has excellent quality images.

Ok, I'll get my manual out and see if I can decide which CF it is. The expanded center circle is not all 11 points, just 4 or 5 lit up?

So what is the best setting for focusing and exposure?

spcalan wrote in post #5717938
So what is the best setting for focusing and exposure?

For most accurate focus the center point is it. I find the other points are quite inaccurate, often to the point of not being usable (of course this depends on what exactly you're trying to focus on, and how much contrast there is/isn't). I find that using the center focus point along with any of the exposure metering work well, but be sure to watch the histogram to ensure you're not losing details.

BeckyMax wrote in post #5715743
Can someone explain the difference between ALL the focus points lighting up in red and just one? When I change the focus point, at one point, they all light up. If I use that setting, will my focus be better? I use AI Servo.

All lights on means that the camera automatically selects which AF point to focus with. This can have very undesirable results, especially in situations where the intended subject has lower contrast while there's another high-contrast object in the frame. The camera's AF system will often be fooled by this. Also, if there are foreground elements they can also distract and confuse the AF, because after all it doesn't know what your intended subject is. If instead you select 1 AF point at a time, you force the camera to focus on whatever that AF point is covering and results are more predictable. Unfortunately the 5D's outer AF points are a lot less accurate and reliable than the center AF point, so focus-recompose using the center AF point is almost a necessity in certain lighting conditions.

For AI Servo, if you think you'll have a hard time "painting" a moving target with the center point alone, it might be worth trying the AF point expansion that activates the 6 invisible (not visible in the viewfinder anyway) AF points that only work in AI Servo. That way you have some wiggle room in that if you miss with the center point hopefully one of the 6 assist points will pick up the target until you bring the center point back on the target again.

In AI Servo mode the camera uses the chosen AF sensor to get initial focus. Thereafter it will allow the other sensors to maintain focus when you drift your aim off target provided that you have allowed expanded AF sensors.

In One Shot mode, allowing more than one sensor lets the camera decide which ones to use. It will choose the sensor(s) that offer the best balance between contrast and close focus distance even if that means it picks a target that is not the one you wanted.

AF expansion is a trade-off between trackability in AI Servo mode and selectability in One Shot mode. AF expansion is often more useful in AI Servo than it is in One Shot. On the 5D you can activate the 6 AF Assist sensors to help out in AI Servo without affecting One Shot mode.

- Alan