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which digital SLR will produce files at least 25MB?

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i have to make a choice, between a powerbook g4, a really great neg scanner capable

of scanning up to at least medium format OR a great digital SLR. i currently use nikon

but i am open here. i plan on shooting stock images and they need files at least



any suggestions?



member asmp and saa

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That is a simple calculation. Every pixels is 3 bytes. (using 8 bit per pixel) For 25Mb, you thus need 25/3 megapixels, which is 8.3. This means you will be looking at a 10MP model like the Canon EOS 1Ds or Kodak DCS14n, which is 14MP, but really not a general purpose camera, only use it when you have the time!


Really, you are getting ripped off here. The 25MB is based on scans from slides. Because a digital SLRs pixel are much cleaner (the image is the original, not a copy!) a 6MP model like the EOS 10D, or even a high quality 4MP model is enough to give the same size prints.


If you just enlarge (interpolate) the image to 25MP, they will never know the difference! ;-)

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<H2>Is this true???</H2>


Do stock agencies really specify their requirements by <B>FILE SIZE</B>, instead of my more logical standards such as resolution, pixel depth, file format, etc. A 25MB JPEG file, a 25MB black and white file, and a 25MB 16 bit/channel TIFF file are all very different animals!

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I have seen it many times, printers, magazines, graphics design studios, etc. ask for file sizes. I guess this is based on the actual number of pixels times 24 bits per pixel, RGB.


Another good one is specifying the files hould be 300dpi, without specifying how many inches they intend to publish it at.


I guess these are just the standard answers the front line people are trained to give, I am sure the people actualy working with your images are smarter than that.

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My 10D, 6mp dslr, when shooting raw converted to 16-bit TIFF

creates a 36MB file. Also my G2, 4MP point and shoot, will create

a 22.2MB, 16-bit TIFF. Or any 5MP camera will create a 16-bit

TIFF file of over 28MB.


So, it seems file size alone is not a good indicator of the quality

of an image. At least to me.

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<i>Do stock agencies really specify their requirements by FILE SIZE</i><p>


Yes. That's what I get asked for, both for stock and advertising. Editorial too, but the requirements are so low it doesn't matter.<p>


I have to assume they know what they're doing, rather than what you or any other photographer might suggest. They're the ones printing the stuff, and they know what they want. That's all that matters.

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There is some sense in specifying file size, assuming you know all the other parameters, leaving those out is just silly and leaves people guessing.


So just saying "25MB" isn't enough. Specifying "an uncompressed 24bpp file of 25mb" does make sense, as you can work out what pixel sizes you need for that.

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A magazine, catalog or anything printed in offset requires 32 to

34 Mb files in CMYK not RGB. Because digital output is ripped to

negatives or plates in CMYK. TIFF images usually. never jpg. so

a 25MB RGB is the same as the 32MB CMYK.

A D100 will deliver about 16MB RGB files=21.3MB, while a 10D

will deliver a 19MB RGBfile=25.3MB. And as digital pixels are

much cleaner than a film scanns both will deliver good quality for

a full page print.

Canon 1Ds is for much larger offset prints like tabloid sizes or

poster sizes.

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Normally uncompressed file sizes are used in conversions when printing; usually RGB 8 bits. If your printer needs CMYK; then the file size is 4/3 larger. If you have 12 and 14 bits per channel; this is fine too. One tends to think in uncompressed RGB megapixels per square foot of giant poster; or megabytes; even if this seems abit weird to the non printer. When one has alot of jobs in the Q of the RIP; it is good to know which ones are well sized; and which ones are "RIP HOGS". Sometimes people will resize images; such they clog up the RIP; and dont add any extra visual detail in the print. This is bad practice; but happens when people dwell on file sizes; instead of actual quality of the image.
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