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Old Jun 28, 2003, 5:51 AM   #1
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Default CF size... Maths.

Prepare for some stupid text coming up. It's simply because of me being a -- at maths, but I've got some questions about CF cards sizes.

In the storage chart of the CP5400, it says it'll capture 6 5MP pictures at Fine compression, storing on a 16MB card. If i buy a 512 MB card, will it only hold 30 pics? Something in my brain seem to be on vacation, I figure.

thanks.
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Old Jun 28, 2003, 6:37 AM   #2
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Hi,

16/6=2,666667

So 1 picture is app. 2,7 MB.

So on a 512MB card you can store 512/2,7=189 pictures.

Greetings,
Frank
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Old Jun 28, 2003, 6:45 AM   #3
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Bear in mind that it's just a factory conservative estimate, but depending on the pictures content most files are actually smaller... So don't be surprised if the camera's picture counter will update in mid-roll and'll show that you can actually go well past ~250's! :P
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Old Jun 28, 2003, 10:05 AM   #4
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thanks everyone =) Think I gotta take that Maths A course all over again ;P
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Old Jun 28, 2003, 10:08 AM   #5
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In my camera the starting counters says I can store 305 images, but I've been able to fit over 380 images. The actual capacity of the card will vary as well, 512MB CF actually having ~486MB, a 1GB having ~972MB. Somewhere I heard Microdrives actually have the full advertised capacity.
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Old Jun 28, 2003, 10:43 AM   #6
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Also jpg compression does better on some scenes and worse on others. For example, scenes with bright blue sky in them (usually a consistant color) will compress a lot more than pictures of fields of flowers (lots of changing detail and color.)

The manufacturer just guesses at the average size of a picture and then does the math. And, as said above, they are conservative. So won't worry, you'll get loads of pictures with a 512MB card. I get over 200 in mine, and I've got a 6.3MP camera.

Eric
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Old Jun 28, 2003, 5:38 PM   #7
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The only real value number on a card is its formatted file size capacity in Mb. Unless you're shooting uncompressed TIFF, in which case you might expect the camera to get the arithmetic right. I can't say what happens when you've filled a card as I never get that close, but I suppose the camera might think there's one shot left, but a detailed scene might just not get saved.

There's another variable factor with any media, that's the formatted storage capacity, and the unformatted bare memory capacity. A 128Mb memory card may contain 128Mb of addressable memory cells, but what's left after formating and the dreaded 'bad block' marking is a bit less.
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Old Jun 28, 2003, 6:54 PM   #8
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Quote:
... but I suppose the camera might think there's one shot left, but a detailed scene might just not get saved.
Actually try to go to the end and the camera is pretty smart... in case of the D7 and the CP990 anyway. If the remaining free area is less than the max conservative estimate then the camera just won't let you take any more picture! In jpeg for example toward the end, switch the setting toward raw/tiff and the card symbol would just flash... and the shutter is locked out , ie when the frame counter says 0. :P
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Old Jun 29, 2003, 3:11 AM   #9
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Indeed there can be variations in size with JPG, forgot to mention that.

Greetings,
Frank
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