M9 LCD Info Inaccurate ?

[kingsley244]

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I have an empty (but formatted) 8GB Sandisk Extreme SD card in my M9. The camera's Compression is set to DNG.

 

The camera's Info says that I have 284 remaining pictures. The SD card bar shows about 60% green and the rest is red. That means I only have about 60% unused space in my SD card, right ? That can't be correct because the card is empty. Under the bar it says 7771MB.

 

Do I have a problem ?

[jose]

You might have bad blocks on the card?. Have you tested with a different one?

[adan]

When you say your card is formatted - how formatted? In the M9? Recently?

 

The megabyte value is the total size of the card - i.e. it will always read 7771 MB even if the card is full of pictures. 8 gigs minus about 230 Mbytes set aside for "housekeeping" files. My 4 Gig card reads 3770 Mbytes (4 gigs minus the same 230 Mb for housekeeping) - and if I take 10 pictures it STILL reads 3770 Mbytes. Normal.

 

If there is an old folder from a different camera (Nikon or Canon or P&S) still on the card, it will be taking up space (as shown by the green/red bar). Those pix will not be readable by the M9, since they are not in a LEICA folder - so the M9 may tell you "No valid pictures in Leica folder" - but that does not mean the card is empty.

 

Check the card using a computer to see if there are any old extra folders within the DCIM folder (and if there is one, make sure you have saved those pictures). Then put the card in the M9 and format it freshly. The green bar should go to 100%.

[kingsley244]

I tried Adan's suggestion and it works. The Info shows the card is 100% empty now.

 

Thanks.

[01af]

The megabyte value is the total size of the card—i. e. it will always read 7771 MB even if the card is full of pictures. 8 GB minus about 230 MB set aside for "housekeeping" files.

There is nothing "set aside for housekeeping".

 

Instead, 8 GB really is 7,771 MB ... umm, approximately. The card manufacturers calculate 1,000 bytes per KB, 1,000 KB per MB, and 1,000 MB per GB. So 8 GB is 8,000,000,000 bytes. Computers, however, calculate 1,024 bytes per KB and 1,024 KB per MB—and a digital camera is a computer in this context. So a card manufacturer's 8 GB are 7,629 computer's (or camera's) MB. So on a 7,771 MB card you actually have 142 MB extra, not 230 MB "set aside".

 

Basically the same applies to hard disks, BTW.

[adan]

OK - (230 Mbytes for directories etc. did seem a bit much). I'm aware of the 1,000 vs. 1,024 disconnect but wasn't sure which way it worked in this case. Thanks.

[Nicoleica]

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Excuse me if I'm wrong. But my experience shows that there is always some space used from the nominal capacity to allow for the partition table, directory and file index structures and tables, and for any blocks mapped as bad by the formatting procedure.

[01af]

Excuse me if I'm wrong. But my experience shows that there is always some space used from the nominal capacity to allow for the partition table, directory and file index structures and tables, and for any blocks mapped as bad by the formatting procedure.

Sure there is some space set aside—but it's not 230 MB! It's more like a couple of KB ... hardly worth mentioning.

 

The overhead used for index tables will grow a bit (or two, note the pun? ) when the medium fills up with files. But on an empty card that's just peanuts.

 

Even the loss from bad blocks usually is unnoticable. One logical sector is 512 bytes; one cluster usually is 4 KB. So you can have hundreds of bad blocks before they add up to just one single megabyte.