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Old Mar 20, 2007, 8:40 PM   #1
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This is a crop of a picture I took today, haven't resized at all but I did recompress in Photoshop to reduce file size, so there's a bit of extra JPEG artifacts. Problem I'm having is that all my photos are just not that sharp, they are coming out rather soft like this sample. Any idea what I am doing wrong? Does the lens just oops, or is it me doing the sucking? :-)
Camera: Pentax K100D
Lens: Sigma 18-125mm/F3.5 - 5.6

Res: 6Mp, high quality JPEG
Shutter: 1/125ms
Aperature: F/19
ISO: 200
Focal Length: 34mm
Metering Mode: Pattern
Flash: No

Any tips would be most welcome.
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Old Mar 20, 2007, 9:19 PM   #2
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I think it could be a couple of things, firstly at f19 the lens is not going to be as sharp as it would be at f8 (looking at MTF charts for this lens that is about the sharpest) however if this is straight out of the camera it looks pretty OK. "How can I say that?" I hear you ask, well unlike point and shoot/prosumer cameras there is not a lot of in camera sharpening and there is an anti-aliasing filter which will soften the shot as well. Part of your post production work should be to apply some form of sharpening, I suggest USM (unsharp mask) which will give all shots the lift needed. I would make this the last part of the PP.
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Old Mar 20, 2007, 9:20 PM   #3
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f/19 may be getting into diffraction limits. How does the lens perform if you keep the aperture around f/8? Have a look at http://www.lonestardigital.com/apert...ion_limits.htm and http://www.cambridgeincolour.com/tut...hotography.htm for details.
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Old Mar 20, 2007, 9:28 PM   #4
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It's hard to tell.

Try taking another picture of something with a pattern and texture (i.e.: a brick wall) at full resolution ( 3008 x 2008 ), Best Quality JPEG. Take multiple shots at different f-stops. Don't do any post processing. Crop to the center until the file size is less than the 250400 byte maximum, and post those.
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Old Mar 20, 2007, 10:55 PM   #5
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Focal Length: 30mm
ISO: 400
Aperture: F4
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Old Mar 20, 2007, 10:57 PM   #6
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Focal Length: 30mm
ISO: 400
Aperture: F5.6
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Old Mar 20, 2007, 10:59 PM   #7
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Focal Length: 30mm
ISO: 400
Aperture: F6.7
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Old Mar 20, 2007, 11:00 PM   #8
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Focal Length: 30mm
ISO: 400
Aperture: F8
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Old Mar 20, 2007, 11:00 PM   #9
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Focal Length: 30mm
ISO: 400
Aperture: F9.5
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Old Mar 20, 2007, 11:01 PM   #10
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Focal Length: 30mm
ISO: 400
Aperture: F11
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