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Old Dec 25, 2003, 2:32 PM   #1
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Default 128mb CF card only reads 122mb

I just got a new camera and i have taken quite a few pictures on it. when i went to format it today the card said that there was only 122mb of usable space....after i formated it. but its a 128mb card, anyone know why this happens?
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Old Dec 25, 2003, 3:30 PM   #2
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What card is it? And not all memory, hard drives, etc usually end up being its amount intended for. Sometimes more, sometimes alittle less. Like if you format say a 80Gig Hard Drive, it might be say 78Gigs when you are done formatting or it might be 80.81Gigs. Its all depending on the hardware/software formatting it.
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Old Dec 25, 2003, 3:56 PM   #3
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it could also depend on what the company says mb stands for
i don't have anything in front of me, but someone else could tell that 1 mb is not 1 million bytes, it is a little over, or sometimes it is 1 million
i hope someone else can make it more clear than me
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Old Dec 25, 2003, 4:38 PM   #4
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I think it's a terminology issue and I wouldn't worry about a few Mb in the description. Firstly there is the difference between unformatted (that is physical memory cells) and formatted (space to store data after you've used up some physical memory for the operating system, format structure, directory tables etc). Then there's the 'elasticity' of storage because a card or HD uses cluster structures file pointer tables etc and a certain amout of slack space is created which is not big enough to be used in files. If I was paranoid about where a few Mb had gone, I'd look at the card with a disc editor like Winhex, to get a second opinion.

I don't think your card manufacturer is short changing you. If you checked out the cards properties as delivered, looking on a pc before doing the first in camera format, I'm sure you'd see the right numbers. Anyway, the card size is usually just a number put in the cards information table, so if this was being used there's no reason why it should be wrong. But if the camera was reading this you wouldn't object and the card could have less than you thought!

Stick your camera on continous movie or large file TIFFs if it will do it and shoot till 'card full'. Add up the file sizes and that will be more of a real practical working capacity figure, but even that, because of byte rounding, will have some error. Sleep sound without worry. VOX
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Old Dec 25, 2003, 8:18 PM   #5
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I have the same problem with my cheap "Ogatech" branded CF card. It's read exactly 122 out of 128. But i dont matter it much though :? What you pay is what you get.. :roll:
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Old Dec 25, 2003, 9:50 PM   #6
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As everyone else has said, don't worry about it. You rarely get the exact size specified. Most makers of memory/harddrive falsely advertise. If you read the fine print, to them a 1 MB is equal to 1000 KB, 1 KB = 1000 Bytes, etc. Technically this is incorrect; 1 MB = 1024 KB, 1 KB = 1024 Bytes. The "24" doesn't sound like much, but it adds up
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Old Dec 25, 2003, 10:05 PM   #7
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This is the same appellation confusion as with hard drives.
An advertised 80 GB means 80 000 000 000 bytes, but we need 1024 bytes to make a kilobyte , and 1024 kilobytes to make a megabyte, and so on.
So the “80GB” drive give only 80 000 000 000 / 1024 = 78 125 000kilobytes , or 76 293 megabytes , or “only” 74.5 gigabytes

The 128 mb CF means 128 000 000 bytes, equals to 128 000 000 /1024 = 125 000 kilobytes, or 122 only “real” megabytes .

PS: yeah, as mdparker point out, it's a manufacturer's "trick" to boots up the apparent capacity of memory devices, for pure marketing/selling point of vue.
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