format CF oddity

I took a 16GB Sandisk Extreme III 30MB/s CF card
and formatted in my 7D (firmware 1.2.1), it gave me
16,003,072 KB total disk space with 500,096 total allocation units on disk.

I took the same CF card and formatted in my 5D2 (firmware 2.0.4), it gave me
16,002,560 KB total disk space with 500,080 total allocation units on disk.

How can this be?

I just did the same test with my 16GB Kingston ElitePro CF card.

On 7D (firmware 1.2.1), it gave me:
15,757,184 KB total disk space with 492,412 total allocation units on disk.

On 5D2 (firmware 2.0.4), it gave me:
15,756,672 KB total disk space with 492,396 total allocation units on disk.

Can it be that the 5dmkII is programmed to format below the full capacity of the card?

It's not even 1 picture's difference. I wouldn't worry about it. I'm guessing the 5D's file system takes up more room on the card than the 7D's.

The 5D2 file system is not taking up more room, it seems to just be registering less of the card on the FAT (file allocation table). The file systems on both camera's format is the standard FAT32 with 32K clusters. Just seems very odd to me.

There are default files added to the file system. Did you compare the difference in files added?

The numbers I posted are "total" capacity, not "available" capacity. So the directories that were added by the camera were not even important.

500kb difference! woot woot!

what is it when you format it in your computer?

Vermin87 wrote in post #10172121
what is it when you format it in your computer?

When I do a quick format on them in my Kingston 19-in-1 reader, they come back with whatever was set by the camera. The command I do from Command Prompt is:
FORMAT x: /FS:FAT32 /Q /A:32K

When I do not use the quick format (without the "/Q" option), they still come back with the same totals as what was previously set by the camera. If I format in the other camera, and do the non-quick format, it will reflect the size of that other camera.

It reflects whichever camera formatted it last. Very odd!

pinoyplaya wrote in post #10171994
500kb difference! woot woot!

On the Sandisk it is 500K difference. On the Kingston it is 1500K difference.

*shrug* it has to do something with how each camera formats it then.

Do you get those results regardless of which order you format the cards in the two cameras? Does it matter whether you format the card in the 7D before or after you format it in the 5D2?

If I format them in the 7D, they always comes out with more space than if I format them in the 5D2.

I can take the card that was formatted in the 5D2 and format it again in the 7D, I would get the larger total space again.

Just weird.

I am now wondering if the 5D2 would recognize the entire 16GB card that was formatted in the 7D.

A German OS doesn't help...
But maybe its those allocation sizes?

Smaller ones on the 5D MK II and larger ones on the 7D? - e.g. 512KB, 4KB, 64KB - unless I am mistaken they can - within small amounts - have an effect on drive size...