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Old Nov 16, 2010, 7:59 PM   #1
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Default K7 and possible Camera 101 question

Ok, so I have the K7 and mainly shoot with a Sigma 17-70 DG. I'm trying to do more modeling shoots and the hardest thing for me for some reason is getting the eyes sharp. I've been using the center focus option instead of the SEL or Auto option. Where I have trouble is when shooting a full body shot. So, this is how I go about it but tell me if I'm wrong.
1. I will usually move the camera up to lock on the eyes,
2. focus center of the eyes,
3. hold it to lock that position
4. and then reposition the camera to make sure I have the full model in the frame.

Sometimes though, I've noticed that I will do this and the photo will give me unsharp eyes. Am I moving to far out for the lens to stay focused on the locked position or is it something with my lens? Should I use the auto feature? I know this might seem simple but frustrates me when I think I have a great shot and then notice blurry eyes.

Thanks in advance!
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Old Nov 16, 2010, 8:06 PM   #2
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Quote:
Originally Posted by maverick96 View Post
Ok, so I have the K7 and mainly shoot with a Sigma 17-70 DG. I'm trying to do more modeling shoots and the hardest thing for me for some reason is getting the eyes sharp. I've been using the center focus option instead of the SEL or Auto option. Where I have trouble is when shooting a full body shot. So, this is how I go about it but tell me if I'm wrong.
1. I will usually move the camera up to lock on the eyes,
2. focus center of the eyes,
3. hold it to lock that position
4. and then reposition the camera to make sure I have the full model in the frame.

Sometimes though, I've noticed that I will do this and the photo will give me unsharp eyes. Am I moving to far out for the lens to stay focused on the locked position or is it something with my lens? Should I use the auto feature? I know this might seem simple but frustrates me when I think I have a great shot and then notice blurry eyes.

Thanks in advance!
That's how I do it.

Is any other part of your image blurry or OOF?
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Old Nov 17, 2010, 1:58 PM   #3
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IIRC, the K7 has selective AF points. Do you have the time to select an AF point which is near the eye, and use that, without repositioning the camera? Lack of perceived sharpness can also be due to insufficient light. If you have a catch light reflecting from the eye, it is also easier for the camera to focus on.

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Old Nov 17, 2010, 2:54 PM   #4
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Back Focus or Front Focus?

For full body shots, I wouldn't expect your technique to be a big issue with most lenses. But, for tighter framing, it could present a problem and cause back focus (focusing behind your intended target if you lock focus and recompose). Here's an article on the subject:

http://www.outbackphoto.com/workshop...y06/essay.html

Also (in addition to the problem that article discussed), many lenses do not have a "flat" focus plane. So, as you recompose so that your subject is more towards the edges of the frame, you could see some focus errors (especially true for wide angle lenses), even if you're not framing that tight (where DOF is shallower), since focus planes with many lenses will have closer subjects in focus as you move away from the center of the frame, as compared to where you focused originally using the Center Point.

If possible, try selecting your focus point instead (versus focusing and recomposing) for better accuracy with more lens designs.
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Old Nov 17, 2010, 3:01 PM   #5
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Hi Maverick,

It's really pretty much a matter of distance from the subject (perspective) and Depth of Field. . .

The Sigma 17-70 is a relatively fast lens, and can have relatively shallow DOF at close subject distances. This can make focusing more critical if you're shooting wide open or close to it.

http://visual-vacations.com/Photogra...pose_sucks.htm

This illustrates why focus and recompose might be inadequate in certain situations, and why having selectable focus points is a nice feature to have.

Center point focus and recompose is all that most people need for most of the situations that arise as either a slower lens or stopping down allows adequate DOF to cover the focus error, but you should at least be aware of this potential angular displacement problem and be able to correct for it if you run into a situation where it applies.

A whole lot of people make the mistake of reading this article and taking it way too seriously -- to the point of using selective focus points all the time. IMO, it's best to use it as a specialty technique as it adds unnecessary complexity to shooting in most situations, but YMMV.

Scott

edit: I see that Jim beat me to this. . .

Last edited by snostorm; Nov 17, 2010 at 3:04 PM.
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Old Nov 17, 2010, 10:54 PM   #6
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Great advice guys! Sounds like whats happening. Question is (since I can't find my manual right now), can someone walk me through the steps on using the selective AF on the K7. Thanks!
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Old Nov 18, 2010, 4:56 AM   #7
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Mav. I don't have the link to hand but if you Google it the manual is downloadable and easily found.
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Old Nov 18, 2010, 12:48 PM   #8
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That's good info to have.
Thanks for sharing.
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Old Nov 18, 2010, 3:03 PM   #9
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Awesom guys. I feel like a kid in a candy store again! Funny how you learn something new even after owning a DSLR for so long. I checked out the manual and played around with the SEL option which did make a difference compared to the Lock and Recompose. Will see if this improves my shots more. Thanks again!
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