6 Replies Latest reply on Feb 26, 2008 10:07 PM by Ramón G Castañeda

    ACR errs in reading "as shot" WB from my D200

      I am working with the latest release of ACR. Recently I have discovered that it does a very poor job of reading the white balance data in the exif from my Nikon D200. First I noted that when the in-camera WB was set to flash (5400K according to Nikon manual) the "as shot" WB temperature displayed in ACR was 6150K. Next I tried setting the in-camera WB to specific temperatures (from 4800K to 6300K). When the raw files were opened in ACR the "as shot" WB readings were all shown as lower temperatures, with a drop ranging from 11 to 14 mired. Compare this to the increase of 23 mired when WB was set to "flash" on camera.

      Is it possible that I have some hidden setting somewhere that is interfering with ACR's reading of the exif WB? Or is this considered a normal deviation? I have searched the archive but find no information concerning this problem.

      Thanks/Mike
        • 1. Re: ACR errs in reading "as shot" WB from my D200
          Ramón G Castañeda Level 4
          It does not "err" in reading the white balance, it deliberately ignores it.

          This has been discussed to death here. Do a forum search; even some of the thread titles will give you an idea that they discuss this question.
          • 2. Re: ACR errs in reading "as shot" WB from my D200
            Panoholic Level 2
            I remember to have read, that Nikon's color temperature specifications are far off the true (measured) values.

            I guess ACR corrects these values. It is logical, as ACR and the DNG convereter act the same way, and the DNG converter has to convert the white balance in Planckian values.

            I suggest you to shoot a white card or alike in different light with different settings and try if ACR shows the white as white.
            • 3. Re: ACR errs in reading "as shot" WB from my D200
              Panoholic Level 2
              Mike,

              I have another suggestion:

              1. Shoot a white sheet in any light, large enough for using the shot as WB preset,

              2. use this shot as WB preset,

              3. shoot it again in the same light, with the preset WB,

              4. compare the temperature in Nikon NX and ACR,

              5. verify if the white sheet is white in ACR,

              6. pick WB on it and compare the resulting temperature/tint with what ACR calculated from the metadata.
              • 4. Re: ACR errs in reading "as shot" WB from my D200
                Level 1
                G Sch

                Thanks for your replies. It may well be that Nikon's color temperature values are off. However 5400K is a reasonable value for a flash exposure, and for ACR to "correct" this to 6150K does not seem reasonable.

                If I set the camera WB to flash (5400K) and take an exposure of a white wall, when the raw image is opened in ACR the "as shot" temp shows 6150K and the image is obviously way too warm. Changing the WB in ACR to 5400K produces a neutral image. Using the WB eyedropper in ACR also shifts the temp to approx. 5400K.

                I don't have access to Nikon NX. What would be the point of using the camera's WB preset capability if ACR is incapable of reading the metadata correctly.
                • 5. Re: ACR errs in reading "as shot" WB from my D200
                  Panoholic Level 2
                  I don't know if ACR is reading the Nikon WB setting incorrectly, or it converts that incorrectly. ACR processes the WB setting generally, however it may be different with some Nikons. It had been for three years ago, IIRC, that Nikon started "cryptographically" encoding the white balance; this had unleashed a huge outcry (I changed to Canon because of this attitude of Nikon). Although David Coffin has broken the encoding in no time, Adobe had reservations for a while.

                  It is possible, that this is the cause for the discrepance.

                  Anyway, it's bad, no question about that. Not all images contain a suitable spot for picking WB.