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Old Jun 12, 2003, 2:59 PM   #1
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Default CF formatting

can anyone explain briefly about formatting compact flash.
How much real space can I expect on say a 512Mb card, or a 1Gb Card

Is there different file system that gets put on depending on the size of the card.
I remember FAT16, had a 512Mb plateau.

ie, are 1Gb cards formatted differently,?

as the numbers i see don't quite add up linearly :?:
http://www.powershot.com/powershot2/s50-45/specs.html

Large / SuperFine (Canon S50) 2,503Kb image at 2,592 x 1,944

32MB 64MB 128MB 256MB 1GB
11 24 49 99 409

this suggests that a 1Gb card is 25Mb more efficient than 4x256Mb cards
I just like to know these details before I invest.

Thanks,
Io
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Old Jun 12, 2003, 5:14 PM   #2
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Fat-16 has a limit of 2G, and all cameras have a 'standard' DCF file system which means the card are interchangeable between cameras, at least in theory :?
Some newer cameras are fat-32 compatible (ie to use those 4G or higher cards), Canon mainly even on their lower end cameras.
http://www.stevesforums.com/phpBB2/v...&highlight=dcf

The reason the pictures do not add up is their file sizes varies by picture content in jpegs (ie the compression varies with the picture details). The number of pictures/card size is only a rough estimate! When you first insert a card the counter usually indicates some frame #, but you can usually go pass it... 8)

For example with my D7 a 5Mpixels camera with a 1G microdrive I can usually go well past 500's when the camera initial counter only showed 420 :roll: (with the 10D it showed less initially, but I haven't got the chance to fill the drive up yet).
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Old Jun 12, 2003, 8:28 PM   #3
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ok, i understand that the real capacity in the field, might be different to what is quoted, but the theoretical, capacity, based on a fixed size of jpeg. (as per the canon data) calculated with typical 2,503Kb jpeg.,
i would have thought the result would be linear, if the actual physical capacities were linear.

Hence, I concluded that some otther efficiency comes into play, on larger CF cards... It's probably something like cluster size, or the like.

If I'm going waste less space, on a 1Gb (because the camera formats it differntly) than on 2 x512Mbs I'd probably go for the 1G, at he outset.
If can factor this into the cost/value.
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Old Jun 13, 2003, 7:11 AM   #4
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I formatted CFs in camera

All 256 mb CF cards use 8 kB (also xD with CF-adapter)
all 512 mb CF Cards use 16 kB

I think, 1 gb needs 32 kB for overhead

Should there be a difference between 1 gb and 2x 512 mb then it ist sooooo small ... 0.0000000000000001% that it makes no matter.

Concentrate at your pictures, not +/- 3 bytes!
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Old Jun 13, 2003, 7:31 AM   #5
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The figures suggest that the discrepancy is 25Mb, not just 3 bytes.

I'd rather know what I'm paying for,

As I haven't got my camera yet, I'm concentrating on what to buy..
I'll forget shopping, and go picture crazy, when it arrives.
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Old Jun 13, 2003, 10:32 AM   #6
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Even for 25 Mb (megabits or megabytes) I don't hang me up.
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