6 Replies Latest reply on Jun 8, 2016 8:46 AM by trshaner

    Help with exposure bias and Nikon D-90

    frankhutch

      I just realized to my surprise that my Nikon D-90 has had its exposure bias adjusted to -2/3 EV for approximately the last year.  I was unaware of this.  I have taken a couple thousand photos.  I am not sure I understand what, if any consequences this would have for me.  What, exactly, does this mean?  As I understand things, this means all the photos I've taken are forced to be 2/3 of a stop underexposed.  Is this correct?  Can I change them all in Lightroom by changing the exposure bias?  Should I attempt to do so?  I do not want to cause further harm but frankly don't really understand the interaction of my images and lightroom enough to know what to do (if anything) to fix.  I would be grateful for any feedback/advice/help.

        • 1. Re: Help with exposure bias and Nikon D-90
          ManiacJoe Adobe Community Professional

          Yes, the -2/3 EV setting has caused all of your photos to be underexposed by 2/3 of a stop.

           

          This is easily fixed in LR by adding the brightness back in. However, in doing so you will also be enhancing some of the digital noise. Thus you may need to add some noise reduction in LR's Detail panel.

           

          Whether or not each image needs any adjustments will need to be judged on a case by case basis.

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          • 2. Re: Help with exposure bias and Nikon D-90
            frankhutch Level 1

            Thanks for the response.  Is the exposure numbering system in Lightroom the same as my camera?  In other words, would I increase the overall exposure for each image by .66 (2/3) to compensate and bring it to what it theoretically should have been?

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            • 3. Re: Help with exposure bias and Nikon D-90
              trshaner Adobe Community Professional & MVP

              frankhutch wrote:

              As I understand things, this means all the photos I've taken are forced to be 2/3 of a stop underexposed. Is this correct? Can I change them all in Lightroom by changing the exposure bias? Should I attempt to do so? I do not want to cause further harm but frankly don't really understand the interaction of my images and lightroom enough to know what to do (if anything) to fix.

              You've been working with image files for a year with the -2/3 EV bias and I assume you've already edited most of them in LR. Going back now and applying a +2/3 (.66) EV correction will simply "undo" the adjustments you have already established. In addition LR's PV2012 Tone controls are image adaptive and simply applying a +2/3 (.66) EV Exposure correction is not going to help very much. Here's a short tutorial on how to properly adjust the PV2102 Tone controls: Re: camera calibration profiles: standard vs neutral

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              • 4. Re: Help with exposure bias and Nikon D-90
                frankhutch Level 1

                Yes, of course.  You are right--I have definitely processed some images and would not want to blindly "correct" them by .66.  I will not likely correct any of them, as they are now how I like them.  But just from the point of view of learning and understanding Lightroom better--do you know if the numeric scale in Lightroom would correspond to the one on my camera?  (i.e. is .66 in Lightroom the equivalent of 2/3 stop in my Nikon?)

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                • 5. Re: Help with exposure bias and Nikon D-90
                  ssprengel Adobe Community Professional & MVP

                  The units of EV in trshaner's answer means, yes, but the link to image-adaptive controls in the same reply means only approximately.

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                  • 6. Re: Help with exposure bias and Nikon D-90
                    trshaner Adobe Community Professional & MVP

                    frankhutch wrote:

                     

                    do you know if the numeric scale in Lightroom would correspond to the one on my camera? (i.e. is .66 in Lightroom the equivalent of 2/3 stop in my Nikon?)

                    The camera and LR numeric EV scales are the same.

                     

                    I just checked a ColorChecker Passport image shot at 0EV and -1.0 EV in-camera Exposure Bias. Using a +1.0 EV LR Exposure adjustment makes ALL of the grayscale patch values equal. I also tried applying -1.0 EV Exposure to the other image file without in-camera bias and the values were also equal. Much to my surprise applying LR Exposure compensation is linear at least for values up to ±1.0 EV. You still may need to add some additional NR dependent on the shooting ISO.

                     

                    Exposure Bias Compensation is Linear in PV2012.jpg