5D Mk III AF system...hints and tips

Finally the 5D III is out there and some are already using it. I have downloaded the part of the user manual dedicated to the new AF system, and while I suspect a little time reading and some hands on when the camera arrives will get me by, I'm sure that others will be more at home with it and able to share their experience.

What this thread will NOT be about, please, is to rubbish this or any other camera's AF or whatever...there are plenty of threads where that can happen.

So...to start I would like to ask the question...is anyone as yet comfortable with the Zone focussing system, and when do you use it?

And is there any advantage in using back button focus or does it tend to nullify the advantages of the new AF system?

Ricardo222 wrote in post #14121619
So...to start I would like to ask the question...is anyone as yet comfortable with the Zone focussing system, and when do you use it?

Coming from the 7D, zone AF is great for things like birds flying against the sky. It has the same issue as any other automatic AF point selection system but at least there's a much smaller selection of wrong points for it to choose. Against the sky where there's not much to confuse it, zone does pretty good and you get the advantage of a larger area to keep the bird contained within so you don't lose focus if the AF point happens to slip off the bird.

What feature of the new AF system would be an issue with BBF?

Alright, let me start out by asking: can you select AF points easily with the joystick like you do with the 5DII? If so, can you detail how it goes? Cos the 5DII sort of has 9 positions on the stick for the 9 points, each one fits.

Maverique wrote in post #14121696
Alright, let me start out by asking: can you select AF points easily with the joystick like you do with the 5DII? If so, can you detail how it goes? Cos the 5DII sort of has 9 positions on the stick for the 9 points, each one fits.

According to the manual the joystick works. And as with other models like the 7D and the various 1 series cameras, the joystick simply moves you along. For example, if you have the center point selected and you want to use the top most point in the center column then you'd move the joystick 4 clicks up.

The camera also allows you to limit the selectable points to 9 or 15, making it faster to get from one side to the other. Limiting the points does not disable the others, so if you use AF point expansion then it can still use the points surrounding the point you selected.

Pretty cool that, so tell me something else. I've only had rather primitive AF so I don't know. In these "pro" cameras, do you focus with several AF points at once or can you go for just the one? Say I want to catch an eye in perfect focus and blur out the rest of the picture.

Maverique wrote in post #14121729
Pretty cool that, so tell me something else. I've only had rather primitive AF so I don't know. In these "pro" cameras, do you focus with several AF points at once or can you go for just the one? Say I want to catch an eye in perfect focus and blur out the rest of the picture.

You select a single point unless you are using "automatic selection" or using zone. Zone is automatic selection but only within an area that you select. Expanded AF lets you select a single point and if it doesn't find anything at that point to lock focus then it will check the surrounding points and use one of them if they are over something to focus on.

More important to your usage is "spot AF" which uses a single AF point but reduces the "size" of the point to about half so that you can be much more precise about what you are placing it on in the viewfinder.

Thank you!

krb wrote in post #14121719
According to the manual the joystick works. And as with other models like the 7D and the various 1 series cameras, the joystick simply moves you along. For example, if you have the center point selected and you want to use the top most point in the center column then you'd move the joystick 4 clicks up.

The camera also allows you to limit the selectable points to 9 or 15, making it faster to get from one side to the other. Limiting the points does not disable the others, so if you use AF point expansion then it can still use the points surrounding the point you selected.

Thanks, Ken. This is exactly the kind of thing that will be useful for people like me moving directly from the 5D2. I really appreciate your replies.

I asked about the back button use because I'm not sure if many use it with the more sophisticated focussing system on the 7D or 1D cameras. (When using the 5D2's centre point only it's absolutely vital of course for birds etc.)

krb wrote in post #14121753
You select a single point unless you are using "automatic selection" or using zone. Zone is automatic selection but only within an area that you select. Expanded AF lets you select a single point and if it doesn't find anything at that point to lock focus then it will check the surrounding points and use one of them if they are over something to focus on.

More important to your usage is "spot AF" which uses a single AF point but reduces the "size" of the point to about half so that you can be much more precise about what you are placing it on in the viewfinder.

That is really useful and something I have yet to pick up from the manual. Thanks!

subscribing. I'm teetering between a 5d2 and 5d3. Auto focus is going to be the tie breaker to get me to spend the extra $1500+. Tired of getting my squirmy kids ears and noses in focus with my 5dc. So I'm really curious how this discussion goes.

weegee wrote in post #14121841
subscribing. I'm teetering between a 5d2 and 5d3. Auto focus is going to be the tie breaker to get me to spend the extra $1500+. Tired of getting my squirmy kids ears and noses in focus with my 5dc. So I'm really curious how this discussion goes.

Keep watching Weegee...When my 5D3 arrives I will add my experiences with the AF as I go.

There have already been useful contributions from Krb, so hopefully more will chip in!

edit: (I wonder what the original Weegee would have thought of the modern cameras? That old Speed Graphic of his did some great work!)

I spoke to someone at CPS today and he told me that BH has received their first HUGE batch of 5D III's so those of you who ordered early should be seeing theirs this week or next.

I'm literally squirming and not sleeping like a little kid before Christmas. Only mad that they've pushed the 1Dx back to May (says the guy at CPS)

I have a great test subject. My almost two yearold daughter. My 7D rarely misses a shot but the 5D2 is nearly hopeless. As soon as I get my 5D3 it will be tested on her

I'm subscribing as well.
Have a 5DII but am looking at the III as well.
But man the 5d2 sure does take a nice picture.
Center point focus all the way.
Looking forward to learning a lot here.

Yes. Can't beat the 5D2 as long as the subject doesn't start moving. Really curious to see how well the new AF locks on. I always use center expanded on my 7D and its hard to use anything else.