CF card capacity on D300 question ...

On my D300, a freshly formatted 4Gb CF card shows '197' as the capacity,

shooting NEF, 12-bit lossless.<p>

On my D80, a freshly formatted 4Gb SD card shows '315' as the capacity,

shooting NEF.<p>

The file sizes are not in the same (approx. 3:2) proportion, more like 11:9,<P>

so the D300 capacity should be more like 260. What might be going on?

On the D80, NEF files are always compressed, and it is lossy compression so that the compression ratio is higher.

 

On the D300, the lossless compression option would initially give you a very conservative remaining frame estimate; essentially it assumes that no compression is possible. If you actually take pictures and therefore put images on the card, you'll end up storing a lot more than 197 NEF files. But since the compression ratio for lossless compression is not as high, and the D300 is 12MP vs. the D80's 10MP, your D300 NEF files (lossless compressed) will tend to be larger (in terms of byte counts) than those from the D80 (always lossy compressed).

D80 (10.2mp) vs D300 ( 12.3mp) So there are 2,100,000 differences right there. Probably the compression schemes differ as well: lossy vs. lossless compression.

Setup the same way as the D80 (12-bit, Compressed NEF), my D300 shows 271 as the capacity on a 4GB CF card. As Shun Cheung notes, the D80 does not do Lossless compression, and that option costs you file size.

Ah, the camera is displaying an overly conservative <i>estimate</i>. They might have assumed some nominal compression.<p>

I <i>might</i> have come up with that if I'd thought a little more about it.<p>

Thanks, Shun.<p>

How lossy is the D80 compression? I had assumed (until now) that it was lossless.

If I set it to 12-bit lossy, I get 270 as the capacity. That is consistent with 12.3 vs. 10.2 Mp images.

"How lossy is the D80 compression? I had assumed (until now) that it was lossless."

 

> It is about the equivalent of 10 bit color depth, but the compression is weighted heavily towards the highlights where it is less noticeable. The debate about the significance of this compression has been going on since the release of the D200 and is addressed in Thom's review of the D300 in which he essentially says it represents a loss of data but one that most users will not notice.