7D focus, what the heck.

Allan.L wrote in post #14247481
I have read that, and I was going to include that in my post. The problem with shooting with AF expansion in situations like this is that there is detail everywhere. From my real-world experience it does seem to *try* the center first and then if it finds something better it switches very quickly to an outer point ( in situations like shooting through branches or BIF against a really busy background).

The outer points are there to assist when an object is moving right? I'm wondering if the camera is not still while shooting a static subject it may switch even faster.

Either way, single point or spot focus Even then one has to realize that the AF zone is a bit bigger than the box itself for single point.

That's true. And on 7D in "landscape orientation" the AF point area tends to be biased slightly above the indicated box area.... only slightly more than the width indicated and about even with the bottom of the box.

Spot Focus is the best choice for BIT (Birds In Trees), so probably would also be best for SIT (Squirrels In Trees) or anything else hiding in a tangle of branches like that. Spot Focus is slower, so might not be a good mode to leave the camera set to use all the time. But it's very useful for exactly this sort of thing.

Usually the camera will try to focus on whatever is closer, but anything can happen when using any of the multiple point "let the camera decide" modes. Expansion, Zone, All Points.... They all leave it too much up to chance and luck in a lot of situations.

Not if one has the sensitivity turned down to 'Slow' in the relevant C.Fn.

I needed spot focus for this. There are branches closer to the camera that I shot through too.

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hollis_f wrote in post #14247597
Not if one has the sensitivity turned down to 'Slow' in the relevant C.Fn.

But that's AI servo sensitivity correct? I was talking about one shot, sorry.

I wanted to believe Canon too. But the real world experience/finding is not consistent with that statement. I have many bird images suffer the same misfocus issue like the OP's squirrel.

For example, with 7D AF Expansion + singel center point, focusing on the nest (not the bird) of the Rufous Honero. Despite the size of the subject, the 7D's still picking up the leaves between the camera and the subject. My old 20D center focus point would have no problem focus on wherere i place the center af square in situation like this.

My 7d has never left spot focus.Weddings,sports portaits,airshows,etc.​.....

The reason i am hesitant to use Spot AF because according to Canon, it slows down the performance a bit. So, i selected Single-point AF (Center) instead of Spot.

cfcRebel wrote in post #14248125
The reason i am hesitant to use Spot AF because according to Canon, it slows down the performance a bit. So, i selected Single-point AF (Center) instead of Spot.

It slows it down, but not THAT much, unless you're trying to track something moving very quickly, spot AF should be fast enough squirrels tend to hop around a bit then stay put long enough to grab a shot. I wouldn't for example use spot af for that same squirrel jumping from limb to limb in the trees.

cfcRebel wrote in post #14247784
I wanted to believe Canon too. But the real world experience/finding is not consistent with that statement. I have many bird images suffer the same misfocus issue like the OP's squirrel.

For example, with 7D AF Expansion + singel center point, focusing on the nest (not the bird) of the Rufous Honero. Despite the size of the subject, the 7D's still picking up the leaves between the camera and the subject. My old 20D center focus point would have no problem focus on wherere i place the center af square in situation like this.

That nest is pretty uniform without any sharply-defined, high contrast edges. I suspect the active focus sensor(s) picked up on a high contrast edge that was closer to the camera than the nest, which is basically what the focus system is designed to do. As noted by a couple of people above, the actual focus sensors cover an area quite a bit larger than the corresponding focus squares in the viewfinder.

stsva wrote in post #14248451
That nest is pretty uniform without any sharply-defined, high contrast edges. I suspect the active focus sensor(s) picked up on a high contrast edge that was closer to the camera than the nest, which is basically what the focus system is designed to do. As noted by a couple of people above, the actual focus sensors cover an area quite a bit larger than the corresponding focus squares in the viewfinder.

Then this supposedly new AF system is no good if looking from a high level. When a simple 20D or 30D has no problem focusing with center focus point on a subject like the nest in the example above, the 7D's sophisticated AF system should not have problem either. It is hard to grasp when seeing today's technology in 7D can't reliably focus on a simple nest like that when a 7 year-old 20D AI Servo locking the nest 100% of the time. A very similar phenomenal also mentioned in this POTN'er's finding too. Check this out.
https://photography-on-the.net …/showthread.php​?t=1115493

If there is any clutter use spot af, this is my default. I only use af expansion for bird in flight.

I have a question regarding ai servo. I actually did have it set to slow in the c.fn (irrelevant in one shot, i know). My concern with that, is when I am using slow ai servo in spot, center or af expansion...would that not cause slow af in some situations?

For example if I am shooting a basketball game, and I use spot focus in ai servo on the face of a moving subject. Would the c.fn set to slow cause delay if I am trying to track their face (while they are darting around)? So should it be set on slow when panning or shooting through trees/bars at a zoo etc, then change it to fast when hitting players or say birds in flight?

The fast/slow setting relates to how quickly the camera will shift to a new subject once tracking of the current one is lost - not how fast or slow the subject is moving.

If your shooting sports you may want it on fast so you can switch between players etc.

Shooting birds you may want it on slow so tracking past trees and poles etc doesnt distract the af.

RobDickinson wrote in post #14250281
The fast/slow setting relates to how quickly the camera will shift to a new subject once tracking of the current one is lost - not how fast or slow the subject is moving.

I realize that. What im getting at is if I am zoomed in on a traget and he is moving so fast in and out of my screen, the camera will have to refocus when I reacquire my target. So in that situation I want it on fast...correct? I guess I just want to verify, that its not a good idea to always leave on slow.

cfcRebel wrote in post #14248822
Then this supposedly new AF system is no good if looking from a high level. When a simple 20D or 30D has no problem focusing with center focus point on a subject like the nest in the example above, the 7D's sophisticated AF system should not have problem either. It is hard to grasp when seeing today's technology in 7D can't reliably focus on a simple nest like that when a 7 year-old 20D AI Servo locking the nest 100% of the time. A very similar phenomenal also mentioned in this POTN'er's finding too. Check this out.
https://photography-on-the.net …/showthread.php​?t=1115493

The 7D in that shot with the bird and nest had the expansion points on, if it was purely in centre point (as the 20D or 30D) it would also likely nail the focus too, going by what the 7D users have said above. So it should be at least as good as them in that mode. Of course, when you need the expansion points, they are only found on the 7D, so the 20D / 30D would lose that round.

It would seem that the sophisticated 7D AF is perfectly capable of locking on to that target as well as the 20D, when used with the correct AF settings. A more sophisticated AF system gives you more tools to get the job done, but equally more chance of picking the wrong tool and cocking it up.

The OP says he has just got the 7D, it takes a little while to learn the way the various AF options work.