Nikon D800 + CF 32GB and 400 shoots...

Phyramide

Hello,

Could You please help me: My logic seems to fail on this:

I've bought a Scandisk 32 GB Extreme CF card for my Nikon D800. I use CF card as a number one card writing RAW in it and ScanDisk 16 GB SD in the second slot for JPF (FINE L). Nikon D800 shows that 400 frames (shoots) are available. When I see the size of the file i get it is around 47 mb (NEF 14-bit lossless compressed). So if I multiply 50mb x 400 shoots = 20000mb ... I do understand that 32Gb is not 32000 mb... a rather something around 30000 mb but still where does the rest 10000 mb go? In my simplifued math it should me around 700 NEF files for a 32 GB card. As the JPG file size is 15 mb so it is 3 times smaller than NEF ... so the 16 GB SD should be fine as a second card for the 32 CF card.

Could You please say where I'm wrong?

PS one more strange thing... If I take the SD card out and put D800 to shoot only RAW ... it shows me 199 shoots???
What is wrong?

Thank You in advance!

DenverShooter

I have the same SanDisk CF card and I find that the available shot count is the same number you get. I also find that the actual number of shots is more than 550. So the D800 is very conservative with the number of available shots and thats not a bad thing. You aren't missing any memory.

Denver Shooter

Msmoto

14-bit lossless compressed gives about 424 shots on a 32GB card. Page 436 of manual. If you set up the second card (16GB) as overflow you should get another 200 shots. But if you use it to record a JPEG file, then 400 is about it.

If you try to figure this out, only someone who is familiar with the inner workings of the card cna explain this, and they usually do this in a language I can never understand...LOL

From a pragmatic point of view, this would seem to be nothing to worry about as your camera is operating as it is supposed to.

Oh, yes, simultaneous posts are always interesting...and as DenverShooter says, you may get more. My suggestion would be this: If you plan on more than 400 exposures on a shoot, carry a spare 32GB card so you will not run out of space.

proudgeek

This is not unique to the D800 I believe. I use 4GB SD cards on my D90 and while the card always says I have room for 262 shoots when it's empty, I frequently get as many as 300. I think DenverShooter's explanation of the camera being "conservative" is probably the right one.

singlecoilpickup

A big part of the reason for the discrepancy is that no two photos are exactly the same size in terms of actual bytes of data. The camera just has to guess based on the space available on the card and the size of an average photo file in the format you're currently set to shoot. I'm sure the estimate does lean toward the conservative side, but the overall point is that because photos are data now and get written to a data store, you cannot have a precisely known number of shots like you could when you had a roll of film with a known number of frames.

Phyramide

I have the same SanDisk CF card and I find that the available shot count is the same number you get. I also find that the actual number of shots is more than 550. So the D800 is very conservative with the number of available shots and thats not a bad thing. You aren't missing any memory.

Thank You very much for the answer. Glad to know that it is not only my bug and seems to be as it is. Ok will try to fill up the card and get the actual number of shots.

14-bit lossless compressed gives about 424 shots on a 32GB card. Page 436 of manual. If you set up the second card (16GB) as overflow you should get another 200 shots. But if you use it to record a JPEG file, then 400 is about it.

Thank You for the link to the manual. Watched the manual once more... Page 436:
1) NEF (RAW) Lossless compressed, 14-bit file size 41,3 # of images 103 (on 8GB Toshiba card)
2) NEF (RAW) uncompressed, 14-bit file size 74,4 # of images 103 (on 8GB Toshiba card)

At that point I thought that was a misspell in the book ... but now I don't get it. Size is smaller ... shot count the same... There is a feeling D800 doesn't understand the choice between NEF (RAW) uncompressed and 14-bit and NEF (RAW) Lossless compressed when chosen as format - software bug?

adamz

I have 64gb sd card for my d800 and I get 800 files on it when I load the card in the camera. on 16gb card I get 199 files and on 8gb card I get 99 files so it's pretty much the same.
as for GB to MB, 32GB is 32768MB

Phyramide

A big part of the reason for the discrepancy is that no two photos are exactly the same size in terms of actual bytes of data. The camera just has to guess based on the space available on the card and the size of an average photo file in the format you're currently set to shoot. .

I do agree with this but still to me it is weird to know that the camera puts at least 30% wrong in it's calculations.

I have 64gb sd card for my d800 and I get 800 files on it when I load the card in the camera. on 16gb card I get 199 files and on 8gb card I get 99 files so it's pretty much the same.
as for GB to MB, 32GB is 32768MB

Ok seems that's the way the things go ...

And as Msmoto said:

... carry a spare 32GB card ...

Thank You for the discussion!

singlecoilpickup

I do agree with this but still to me it is weird to know that the camera puts at least 30% wrong in it's calculations.

The likely answer to that is easy - lazy/sloppy code doing the math. I see it all the time in the work I do. Just be thankful it's not 30% off in the wrong direction...

TaoTeJared

A big part of the reason for the discrepancy is that no two photos are exactly the same size in terms of actual bytes of data. The camera just has to guess based on the space available on the card and the size of an average photo file in the format you're currently set to shoot. .

I do agree with this but still to me it is weird to know that the camera puts at least 30% wrong in it's calculations.

I have taken raw files that were 75mb, and even had one go to 78mb. That was of a christmas tree! It all has to do with the number of colors in the image, contrast, lighting etc. High color and medium-high contrast across the whole image produces huge files. On the other side, a really high contrast portrait is generally about 38mb +/- for me. On the low end I have a few that are only 25mb (Low color and looked more B&W.) If you figure that is about a 25% increase in the "base" file size, Nikon is conservative, but I would rather have space left, than no space at all - that is where problems happen.

haroldp

They are not 'wrong'.
Since lossless compression size cannot be predicted ( I have seen 40 - 65 mb per raw frame on a D800 ) before actual data is known, (lossy compression can because data will be discarded until the target size is reached) they err on the side of not unexpectedly running you out of space. The method seems to be to assume that all new photo's will have almost zero compression for predictive purposes, but subtracting actual size for photo's already taken. As you fill the card the predictions of what is left get more accurate.

All Nikon DSLR's which support lossless compression that I have used (D3, D300, D700, D3x, D800e) do it this way.

It is easy to predict after you get used to it.

For the record, since it is base 2 math, a k byte is actually 1.024 bytes, an mb is actually 1,024,k bytes , a gb is 1,024 mb.

Formatting and blocking of devices th reduces the actual amount usable.

Regards ... H

Ironheart

This is the same as the "Distance to Empty" calculations that most modern cars will give you on the dashboard. If you start driving aggressively or carefully, you can watch the number go down or up. YMMV, literally.