Focus question on 5DII....hidden af points

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Duncan.F

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Duncan
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Hi,
A question for anyone who has knowledge of how the hidden central AF points work. I took a large number of shots using the centre AF point only, focussing on the face of the performer, usually the eye. The rear screen on replay appears to confirm the hit where I aimed. I was using a 24-70 at about 15-20ft range.
However, I found that when I review the shots a lot are not sharply focussed on the face but pick up the microphone or something else. I wondered whether it is my technique or the AF system.... I also took some shots with the 70-200 L IS and the sharpness was generally much better..
Any thoughts?

Cheers,

Dunc
 
Open the file in DPP and get it to show you where the focus point is...

The 70-200 is a fantastic lens, they are generally very sharp.

Never used a 24-70 not sure how good it is

what f- stop did you use for the shots?

Cheers
 
Hi
I am using Photoshop elements 5, not sure I can ID the focus point....? I was in TV mode 1/200 most of the shots are 3.5/4

Cheers

Dunc
 
Were you using focus lock / recompose with the center focus point??

If so this is probably where your problem lies, especially at wide apertures.

Effect will have been lessened as you moved back to use the 70-200.

HTH

David
 
At least on my 7D using a single focus point, the point is actually quite a bit larger than the small square shown on the viewfinder. I think in reality the points form an almost interconnected grid instead of being separated by empty space as you'd think from the viewfinder.

The 7D has a separate "spot AF" mode where the AF area is the size of the viewfinder square.. Personally I don't use it that much as it's a very small area for the sensor to find contrasting lines to focus on.
 
vaizki said:
At least on my 7D using a single focus point, the point is actually quite a bit larger than the small square shown on the viewfinder. I think in reality the points form an almost interconnected grid instead of being separated by empty space as you'd think from the viewfinder.

The 7D has a separate "spot AF" mode where the AF area is the size of the viewfinder square.. Personally I don't use it that much as it's a very small area for the sensor to find contrasting lines to focus on.
Click to expand...

:plusone:

The spot point is great for macro or when you want to focus on an eye in a portrait etc...
 
Duncan.F said:
Hi
I am using Photoshop elements 5, not sure I can ID the focus point....? I was in TV mode 1/200 most of the shots are 3.5/4

Cheers

Dunc
Click to expand...

Load dpp (its free and comes with Canons) it can show you where the focus point is.... (latest version is 3.8 something..
 
Hi Guys,
Thanks for the replies, been out working hard so just catching up! I think I will experiment at my next gig and use either the top AF point [for face in portrait mode] or all points active.

Cheers,

Dunc
 
Duncan.F said:
Hi Guys,
Thanks for the replies, been out working hard so just catching up! I think I will experiment at my next gig and use either the top AF point [for face in portrait mode] or all points active.

Cheers,

Dunc
Click to expand...

All points active will pick up the mic stand....
 
AFAIK the Hidden AF points are only functional in AI Servo.

Could anyone else confirm this?

EDIT - Just confirmed this in the manual.
 
Ok so I got interested in the 5D2 focus points, especially since everybody tells me I need to go full-frame from my 7D :lol:

And then I checked out the viewfinder... image stolen from dpreview.com:
viewfinderview.jpg


Err-WHAT? I never realized that the 5D mkII focus points are grouped like that in the center of the frame! And there's 4 (or is it 6?) hidden focus points MORE in there? And I peeked at the 1Ds series focus points and they're not much better in spread :eek:

As a 7D and 1D owner who also likes to shoot stuff that moves faster than I do, this is looking like a killer "unfeature". I'm loving the wider coverage of AF points in these bodies.

I would have to learn to focus & recompose (again) with large apertures with an AF point grouping like that :thumbsdown: Sorry for the thread hijack, this was a bit of a shock to me.
 
But the 5d2 has the best image quality out there pretty much. To get both the 5d sensor and the 7d focussing will cost you whatever they decide upon for the 1D4s when it gets released.

As for the OP sounds like missed focus, which is easy to do. Was it the 24-70L, if so that lens is sharp as a sharp thing. Sounds like a bit of missed focus has happened.
 
Willid1 said:
Were you using focus lock / recompose with the center focus point??

If so this is probably where your problem lies, especially at wide apertures.

Effect will have been lessened as you moved back to use the 70-200.

HTH

David
Click to expand...

Sounds likely. And if you give the AF any choice, bearing in mind it is active a bit outside the marked area, it will go to the nearest point eg microphone.

BTW, when you check the focus point it will only tell you which point was used, not what it was covering when the lens was focused. If you use focus-recompose, that will obviously be different.

Jukka, it's a very unusual subject that cannot be accommodated by the 5D2's AF points. Not heard that criticism before. IMHO the 7D's multitude of AF options are too clever for its own good ;)
 
HoppyUK said:
Jukka, it's a very unusual subject that cannot be accommodated by the 5D2's AF points. Not heard that criticism before. IMHO the 7D's multitude of AF options are too clever for its own good ;)
Click to expand...

Well glad to hear that.. My main worry is/was with ai servo and fast moving targets getting outside the focus point coverage. And I actually like the 7d focus system a lot better than the 40d one or even the 1d in terms of setup and use. Of course the 1d af with 45 points is amazing but changing focus points is a pain.

Took me 4-5 months to get used to the 7d af though ;)
 
vaizki said:
Well glad to hear that.. My main worry is/was with ai servo and fast moving targets getting outside the focus point coverage. And I actually like the 7d focus system a lot better than the 40d one or even the 1d in terms of setup and use. Of course the 1d af with 45 points is amazing but changing focus points is a pain.

Took me 4-5 months to get used to the 7d af though ;)
Click to expand...

5D2 is essentially the same AF system as the 40D.

Sounds like the 7D was made for you ;) TBH I'm not very demanding of AF in the same way as I can see that you would be as I don't shoot those kind of subjects and it's centre-point only for me 90% of the time.
 
What are we supposed to be looking for?

No reason why those images shouldn't be perfectly focused, and you've also got plenty of depth of field available.
 
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