4 Replies Latest reply on Jun 19, 2015 11:48 AM by BenjyvC

    how literal are exposure adjustments?

    BenjyvC Level 1

      I'm testing a custom strobe system under varying conditions to learn the effect on exposure. I wish to lock the exposure in the camera, the use Exposure in Lightroom to equalize one image against the next, which is useful for decimal values and also for doing this across numerous images. My question is, is a 1.0 adjustment to Exposure in LR equivalent to a 1-stop difference in the camera? Many thanks.

        • 1. Re: how literal are exposure adjustments?
          dj_paige Level 9

          Perhaps in the mid-tones you might find a rough equivalence, but as far as the highlights and shadows are concerned, the algorithm in Lightroom tries to prevent blowing out the highlights and prevent losing all the detail in the shadows, so most likely the equivalence between camera and Lightroom does not hold for shadows and highlights.

          • 2. Re: how literal are exposure adjustments?
            Bob Somrak Level 5

            You could switch to Process Version 2010 as the sliders are not as "ADAPTIVE" as they are in PV 2012 for the highlights and shadows when using the Exposure slider.

            • 3. Re: how literal are exposure adjustments?
              dj_paige Level 9

              Even there, the camera sensor reacts to light differently than whatever the exposure algorithm is in Lightroom. We know that the camera sensor (and film too) react to light according to an S-shaped curve, and while Adobe doesn't say exactly what its exposure algorithm is, I'm pretty darn sure it doesn't do the same things as your camera sensor.

               

              So, to answer the original question, there are going to be differences between a 1-stop change in exposure in the camera, and a 1-stop change in Lightroom.

              • 4. Re: how literal are exposure adjustments?
                BenjyvC Level 1

                Thanks, All,

                 

                Pretty clear, if definitive values are important, don't rely on LR

                Exposure. I'll now do this in Photoshop, convert to Lab color, which allows

                eye dropper to sample luminance. I'll begin with a series of exposures

                running through each aperture, sample one spot across all exposures and

                noting shift in luminance. I can then compare the progression in luminance

                values to stops, see if the relationship is linear, establish whatever

                sliding scale. Then locking settings across all exposures and only varying

                the strobe values, I can study the changes and convert back to stops. Valid?

                 

                Thanks

                 

                Sent from my iPhone