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Old Jul 20, 2005, 10:05 AM   #1
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I noticed that with my last batch of pictures with my 20d that there were a few pictures whose file size was around 800 k instead of the usual 3 megs.

I take all my pictures on Large JPEG. The interesting thing is that there are two near Identical, (same subject) pictures withfile sizes of 850k and 2700k.

Seems kind of odd to me.:?
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Old Jul 20, 2005, 12:26 PM   #2
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Not sure this is your case, but a few things I've noticed:

1. Higher ISO = larger file size

2. More noise = larger file size. So, even if you took the same photo - if one version has more noise than the other you would get a larger file (you might have more noise because the aperture/shutter time changed so that caused an increase in noise).

Those have been the two instances where I've noticed an increase in file size - take that for what it's worth.
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Old Jul 20, 2005, 5:02 PM   #3
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The subject of the picture can also havea bigeffect on file size. For example, a seascape will usually be much smaller than a more complex picture containing a lot of detail, like leaves or other small parts. If you need proof, take pictures of fireworks or Christmas lights and you'll be convinced.
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Old Jul 21, 2005, 6:12 AM   #4
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but he's comparing "near identical" shots of the same subject, not open sky to xmas lights. Even if the camera selected a different ISO, one should not be 3 TIMES the size of the other. They should probably be within 10% of each other, but still would not likely ever be identical.

Something is different between the settings of the 2. Have you checked the EXIF data of each? I think that one somehow is either is different resolution or different level of compression. How could that happen? don't know.
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Old Jul 25, 2005, 1:33 PM   #5
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Yes I have checked the EXIF and can not find any differences. Same ISO shutter speed, subject etc.

If I knew how to send the larger files or the EXIF I would do it so you can see what I mean.

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Old Jul 25, 2005, 2:28 PM   #6
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Yes, 800K is way too small. No way a regular size 8 MPfile from a 20Dgets compressed that small at the largeJPEG setting, even a subjectat ISO 100with little detail. Somethingisdifferent either in your selections before shooting or in some image editing you did after the fact.

Did you do any image editing, or did you check these right out of the camera after downloading them before editing? There is a logical answer, but there's a piece of the puzzle missing that we don't know.
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