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08-25-2012, 02:12 PM   #1
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Why isn't this image sharp ?

I took this with the k-5 and the FA*85. Information is in the exif. I converted from RAW in Photoshop 6.0

I have more questions than the heading of this thread, such as;

- the lack of sharpness

- why is there so much noise

I'm thinking because of underexposure. But, despite that, I expected a sharper image since my FA*85 nearly almost gave me sharper images than this at 1.8. I also used sufficient shutter speed to freeze the moment.

here is the image (full size when opened alone in a new tab) ;

Last edited by Crosshair; 08-25-2012 at 02:29 PM.
08-25-2012, 02:24 PM   #2
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I think the main problems are that the person is relatively far away and the lens was wide open. It is also possible the focus is a little off, especially since the DoF at that aperture is very thin. The noise might also be caused by humidity of the air and amplified by the post processing. That is the only things I can come up with.
But if you scale the photo down a bit it immediately looks better.
08-25-2012, 02:47 PM   #3
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Focus is definitely off, you can see it in the chromatic aberration outlining him.
08-25-2012, 03:00 PM   #4
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I think that there are three issues that I can see, noting that there is a lot of EXIF info missing (such as focus mode):
(1) I wouldn't expect a really sharp shot at f1.8 out of any lens except under perhaps perfect controlled conditions
(2) The histogram is way over to the left - the shot is basically underexposed (hence noise). I note a -1.7 exposure bias
(3) I note that EXIF has a value for "saturation" of "High Saturation" - have you done something in post processing to boost saturation, and thereby boosted the noise ?

Without the focus mode info in EXIF, it is hard to tell what you sctually focused on, or whether you used single shot, held down the shutter button for a 'long' time before shooting, or used AF.C, or multi-point or single point focus. All of these settings can lead to different results.

08-25-2012, 04:12 PM   #5
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I'll second those who say that focus is off, plain and simply.

Something else that befuddles me is the "specks" on the right-hand side of the boy, looking as-if you were enlarging from a negative with some dust/dirt on it.....Something on your sensor or the rear element of your lens?
08-25-2012, 05:27 PM   #6
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Something on your sensor or the rear element of your lens?
There are speckles, but they would not show if they were on the lens or sensor, especially wide open. I'd say water spray?
08-25-2012, 05:35 PM   #7
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QuoteOriginally posted by tclausen Quote
Something else that befuddles me is the "specks"
This would just be a few bits of water as it looks like the subject is wet.

I suggest a little bit of miss focus, under exposure, wide aperture and fast moving subject could all contribute to create "softness" in the image.
08-25-2012, 07:53 PM   #8
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I'm guessing you had water spray/splashing going on and the camera autofocused on that rather then the kid. Add in the underexposure and the obvious mugginess of the air, and there you go.

08-25-2012, 08:31 PM   #9
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I believe it's underexposure as the root cause.

Underexposure compresses all of the data into the bottom end of the sensor's dynamic range. That will cause muddiness making you think it's out of focus, and signal drop-out (noise).

I pulled the photo into CS4 and let it auto-correct tone & contrast and it's a good 2 stops under exposed. I don't think it missed focus. He's pretty clear once you bring up the levels. I don't see any CA or fringing either.
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