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Old Dec 26, 2006, 9:58 AM   #1
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So many of my pictures are not in sharp focus. I don't understand what I'm doing wrong when I'm using AF, wait for the green light to show focus, and then take the picture. These are usually indoor pictures but not always.

I used to think it was due to camera shake and so I bought a camera with I.S. Unfortunately, I don't see much of a difference.

I think it must be operator error since I've seen this with different cameras, but I don't know how to correct it. Any suggestions?

Thanks,

Karen
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Old Dec 26, 2006, 10:24 AM   #2
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Karen,

Please post some example pictures.
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Old Dec 26, 2006, 10:49 AM   #3
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Both of these pictures were taken with a 50mm prime lens, F/2.0, with flash, 1/60". I focused on the words on the heart-shaped plaque.

Ironically, the second photo is with anti-shake turned off. This picture is what I would like to see.

Karen





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Old Dec 26, 2006, 12:42 PM   #4
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Hi Karen-

What focus zone are you using? I tend to use center area focusing and I focus on a specific object and then re-rame the photo, and it works nicely. Both of your sample photos look pretty good, perhaps it is the image reduction.

Sarah
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Old Dec 26, 2006, 1:15 PM   #5
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Hi, Sarah.

Thanks for looking at my examples. I used center focus. A lot of my pictures are useable (like the first one posted here), just not always as crisp and sharp as I'd like. I'm sure there is something that would improve my technique. Guess I'll do more experimenting.

Karen
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Old Dec 26, 2006, 1:46 PM   #6
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I think the biggest difficulty in these samples is that the strong backlighting mkes it very difficult to get the subject well exposed. So you're probably not getting as much detail as you could in the bricks and wall hangings mostly due to the light.

Though I'll add that autofocus normally doesn't always give the best possible focus. It should be able to quickly deliver an acceptably focused shot, which is useful for most candid shots, action shots, etc. But if you are going to be picky about getting the sharpest possible detail from a still shot with your prime lens, you may want to fine tune the focus manually. Macro shooters for example, normally prefer to focus manually.

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Old Dec 26, 2006, 1:52 PM   #7
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Karen,

These photos look decent to me as well. You didn't mention a camera and the EXIF data is gone from you'rephotos - I'm assuming it's the Pentax or Sony Alpha based on your mention of a 50mm 2.0 lens and anti-shake.

A couple points to be aware of:

1. DSLRs don't do as much in-camera sharpening as digicams, so virtually all images will benefit from USM in post processing (or, you can turn up the in-camera sharpening if you prefer less control over the sharpening)

2. DOF - when shooting at wide apertures you don't have as much room for error on focusing. Probably not a huge issue here - if this was taken from say 12' away, DOF would be about 16 inches - still plenty. But you should be aware this could cause you problems when shooting closer subjects and using the focus-and-recompose method Sarah suggested. With a digicam, shallow DOF isn't an issue. If this was 5 feet away, your DOF would only be 2.8 inches - so using a focus and recompose method could soften up the results.

3. Be aware that focus areas in cameras are generally larger than the focus points you see. And the camera uses contrast to determine focus. So, while you think the whole focus point is on your subject, part of the focus AREA may be on something else - and the camera may select that something else to focus on - if that something else doesn't have as much contrast then focus can be soft. Usually not a huge issue with narrower apertures or with a digicam (that has large DOF for all apertures) but the combination of this factor and shallow DOF can lead to softer images than you want.

4. Low light focus accuracy of camera - not all cameras are exactly the same. Some cameras focus better in low light than others - just like some focus faster. Take a look at Steve's review of your camera and Phil's review on dpreview.com - see if either one of them commented on low light focus ability of your particular camera. They may or may not have.

Still - with USM I think the photos will be just fine.
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Old Dec 26, 2006, 4:57 PM   #8
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Thank you all for your comments.The words on the small heart look much sharper to me on the second sample. I've had friends tell me that I'm too critical, but I didn't believe them. Maybe they were right. I don't think I can see clearly enough to focus manually so I'll have to learn to accept the autofocus.

Thanks again,

Karen
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Old Dec 26, 2006, 8:11 PM   #9
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I suspect that the camera wasn't focusing on the same thing. Is the yellow tile(?) in the lower area further back than the parts you want in focus? If so, the top one has more of the tile showing (pointed further down) so it might have focused on the backgroung tile. At f/2 the step back doesn't have to be much (a few inches - several centimeters) to cause what you are seeing.

Take a look at the uncropped photos and figure out where the center of each is. That might tell you something.
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Old Jan 23, 2007, 3:02 PM   #10
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I think your problem in these may be that your camera was not perpendicular to the plain of the subject leaving parts of the subject out of focus. When shooting close-ups with large aperatures like f2 you to have the camera square in relation to the subject to have all the subject fall within the depth of field.

A. C.


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