Mike Chaney's Tech Corner

Is Nikon storing high ISO setting information in a strange way?  I recently took a series of photos in very low light with ISO setting at HI 0.7. (D600)  For the out of the camera jpegs, QU lists the ISO as N/A. But what really surprised me was the raw images where QU says they are ISO 100 and of course they are thus represented as more noise than photo and are not even as good as the out of camera jpegs.  Up to ISO 6400, QU seems to really rescue many of these photos (ok they aren't that good photographically anyway); this is the first time I have tried any of those really high (>6400) ISO settings.  Am I missing a setting somewhere, or is the ISO value in the wrong place? 

Mel W Columbia Md.

Hi Mel,
I downloaded some D600 nef and jpeg samples and cannot see a problem.
http://www.photographyblog.com/reviews/nikon_d600_review/sample_images/ (http://www.photographyblog.com/reviews/nikon_d600_review/sample_images/)
All iso values are reported correctly for raw and jpeg.
Are your images being changed by some other software before viewing in QU?
I do not understand what you mean by:
ISO 100 should have less noise than say ISO 400, so QU takes that into account in raw processing.
Terry

No - what I mean is, the camera ISO was set to HI 0.7 (approx ISO 11000) which is in fact was shows when I view the image in the camera.  But QU shows it as ISO 100 and full of noise as if greatly underexposed (which it was). And no, I have not done anything else to the image - just dumped it from the flash card into the computer.

Seems like dcraw is mis-reading the iso value; one for Mike to check I think.
Terry

Mel, we can guess what Mike will say, "Please send the image to Terry, Mike or Fred..."

Then he can read it abd see where the flaw likes.

Fred

I can do that - although it is of course very large.  But I don't think this is Mike's problem or even a dcraw problem.   QU is doing fine with all of the "normal" ISO values certainly up to 3200 (and probably 6400).  It's only the "HI" numbers that are not coming out right either for raw or out of the camera jpegs.  That leads me to think that Nikon is not storing the high ISO numbers in the "normal" place in the image - perhaps not storing it at all or putting it somewhere that only their own software can find.  Even for the HI ISO out of the camera jpegs, QU shows N/A for the ISO which makes me think that Nikon is not putting it where it should be.   Not that big a deal for me because I don't do too much HI ISO stuff and to the extent that I have, the post processing with the newer QU NR functions has been great

Mel,

I downloaded an ISO 25,600 raw D600 file from Imaging Resource and sure enough, as far as the ISO speed rating, the NEF is naff.  ;)  It works up to and including ISO 6400 but after ISO 6400, Nikon stops storing the ISO speed rating in the usual EXIF ISO tag and stores it in Makernotes.  I checked the Makernotes reader that I have and it can't access the new value.  DCRAW does read the ISO as 100 which is what you see in QU, so it's possible that the next DCRAW update will address this and be able to decipher the "moved value".  Nothing I can do from my side.

Regards,
Mike

Mike - Thank you!  It's good to know that my suspicion was correct even though I clearly don't have a detailed knowledge of the NEF roadmap. Yet another gift from Nikon to its loyal customer base.