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08-31-2013, 10:08 PM   #1
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filesize

why do i get 20mb raw files of the Q and 12mb raw files of the K-X ?!

09-01-2013, 06:05 AM   #2
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I don't see 20MB anywhere in the manual, is that your actual file on disk?
The Q outputs only DNG, so it can't be a matter of DNG/PEF.

The Q manual on page 237 (PDF): 12MB for RAW (4000x3000 px).
The K-x manual on page 298 (PDF): 12MB for RAW (4288x2848 px)
09-01-2013, 06:30 AM   #3
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The 12 megapixel raw files from my Q-10 are around 20 megabytes in size.

I have no idea about the K-x, but remember megabytes are not the same as megapixels.
09-01-2013, 06:44 AM   #4
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Yep, you are right. The manual says "12M", which is mega pixels, not mega bytes.
Thanks.

09-01-2013, 06:52 AM - 1 Like   #5
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Both the Q and the K-x use 12 bits per pixel (a byte and a half), but the K-x compresses the sensor data, the Q doesn't. Pentax's excuse for this is limited processing power in the Q.

So you always get 18MB of sensor data. Then there's also a "preview" jpeg (exactly the same data you get in the separate jpeg file if you use raw+jpeg). (Both cameras include a preview, but on the K-x the quality is lower than the separate files.)
09-01-2013, 07:22 AM   #6
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but the raw files of the Q differ in size ... i got some with 23 "megabyte" and others under 20..

the argument with the processing power of the Q is funny ... the thing can render the effects on the 1080p stream but cant compress a raw file like the k-x .... ridiculous.
09-01-2013, 08:44 AM   #7
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QuoteOriginally posted by paranoia23 Quote
but the raw files of the Q differ in size ... i got some with 23 "megabyte" and others under 20..
I'm going to repeat myself: The raw file also contains a jpeg, exactly the same jpeg data you would get with raw+jpeg (or just jpeg). Take a few shots with raw+jpeg under differing conditions. You'll see that the the size difference is very close.

QuoteOriginally posted by paranoia23 Quote
the argument with the processing power of the Q is funny ... the thing can render the effects on the 1080p stream but cant compress a raw file like the k-x .... ridiculous.
It's probably not done with a general purpose CPU. (Same way a graphics card in a PC is fast only at some things.) Not that I actually believe they couldn't get decent performance on raw compression with the available hardware, but it's at least possible they can't.
09-07-2013, 01:48 AM   #8
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It's because the DNG Raw format doesn't have any compression, the PEF and all other Raw formats do. On a Q the file size is always 20Mb for a Raw file, the PEF files will all be different sizes depending on content, those with lots of fussy detail will be larger than those with just a few continuous tones.

Chris


Last edited by ChrisJ; 09-07-2013 at 01:56 AM.
09-07-2013, 04:09 AM   #9
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QuoteOriginally posted by ChrisJ Quote
It's because the DNG Raw format doesn't have any compression, the PEF and all other Raw formats do. On a Q the file size is always 20Mb for a Raw file, the PEF files will all be different sizes depending on content, those with lots of fussy detail will be larger than those with just a few continuous tones.
This is mostly wrong. The Q only supports DNG, so PEF is irrelevant. Modern Pentax DSLR cameras support compression on both DNG and PEF (and in some very modern instances don't support PEF). The file size of any RAW file, regardless of format, will always vary even if the RAW data is uncompressed, because there is an embedded JPEG, the size of which varies. On the Q the RAW data is uncompressed, and the JPEG data is whatever quality you set for JPEGs. (Unlike the K-5, where the JPEG data in the RAW is always crap quality.)

And I'd already posted the Q-relevant parts of this in the post right before yours too.
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