----- Original Message ----- From: "Gary Fisher" <[EMAIL PROTECTED]>
Largest Raw file: 10.5 MB (11,033,186 bytes) Size on Disk: 10.5 MB (11,042,816 bytes)
Smallest Raw file: 7.16 MB (7,512,755 bytes) Size on Disk: 7.17 MB (7,520,256 bytes)
Average Raw file size: 8,727,539.66 bytes.
Of course (as can be seen from the figures) the size of Raw files can vary quite a bit, so you could fit a few more or a few less dependent on subject matter.
Why does the Raw file size vary ? I would think that RAW is RAW, uncompressed, the size of which depends on the number of activated pixels, therefore constant for each shot, and very close the the number of Mpixels of the camera.
RAW is compressed in a proprietary fashion. TIFF, which some cameras can write, is basically uncompressed and every picture is the same size, but can be compressed with basic LZW compression to maybe a 2:1 ratio.
I had a test with the G3(only digital in hand) shooting a uniform surface and a normal shot, to see if the uniform one would give a smaller file (due to compression), but no. Apparently higher ISO pictures create larger files(400 Vs 100 ISO) but no more conclusions.
If you could really produce a shot with no variation across the whole surface in any of the channels, ie, no noise, no colour variation, no luminance variation, the jpeg file even from a very large sensor camera would be under 10K. However, such no-variation files are impossible to produce in real life.
If you shoot a very simple object in front of a uniform surface, evenly lit, with a lens that exhibits minimal vignetting at the shooting aperture, at lowest ISO, you can get a file that is about 25% of one that is shot at high ISO of a fall scene of trees turning colour and some bare sections, taken so that about 10 trees fill the frame, ie, very detailed and drastic changes in colour and luminance every few pixels.
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