Help me understand memory card storage

[kenny]

i must be missing something. My RAW files for 14bit compressed are roughly 19MB

My thinking would be that an 8G card then should hold roughly 400 pics

However according to the manual of the nikon d7000 an 8g card would hold 223. Why is it only half? What don't I understand

Tia

 

[SkaGoat]

When you put the card in your camera, how many photos does it say it can store?

You can't use straight math, mostly because there is space lost when you format the card, also if your photo uses half of an available block, you lose the whole block.

 

[SkaGoat]

So I did a little googling, a person on DPReview's forums had the exact same question, this is an answer provided by someone

All I use are 8GB cards (got my D7000 in March 2012) and while camera will suggest 224 or 223, the actual number or 14-bit RAW files is 300-340. Just yesterday, I had 348 frames and camera's software estimated space for additional 40. Files typically end up in range of 17-21MB each.

 

[pjacobi]

Raw files are usually loss-less compressed. Some images compress very small, other image will not compress as much. The actual number of images that fit on a card is variable. The number in the manually was probably worst-case with little compression.