Someone please help me understand this

[AlfromLA]

I have two cards for my camera. One is a 4GB SanDisk Ultra II & the other is a 2GB PNY Optima SD card.

The 4gb says it has enough room for 276 shots, the 2 gb says 515. Now can someone explain this to me?

 

[icassell]

It depends on the file size of an individual image. There is a big range in possible file size from JPG to RAW. It also depends on the camera used. If you save RAW on a 6MP camera, that would be about half the file size of RAW on a 12MP camera. Does the card specify the details?

 

[bigtwinky]

As stated, different pictures types will have different sizes. The numbers they put on there aren't exact values as they don't know what type of pictures you will be taking.

On my XSI, I can shoot in RAW, in jpg, or have a RAW and a jpg created each time I take a picture.
When shooting in jpg, I have 3-4 different quality types that I can chose which will affect the size of the picture.

The fact that you are looking at 2 different brands could explain why the 4gb is not double the size of the 2gb. They all have their standards by which they decide on the size of image used to be quoted on the package for marketing purposes.

 

[AlfromLA]

Seems really weird, I would automatically think more pictures would fit on the bigger card.

the 4BG card also says SD HC & 15 MB/s

 

[Overread]

wait a sec,
the cards - I take it the number of savable images is taken from when you put the card in the camera yes?
If so then I think you changed your save mode at some point to leave the difference.

If its on the packaging or website then its really because the manufacturers have chosen different base filesizes which is why there is a difference

 

[Big Mike]

Seems really weird, I would automatically think more pictures would fit on the bigger card.

More photos will fit on a bigger card...there must be a mix up somewhere.

Is there anything saved on the card?