Question about the raw histogram and exposing to the right

When exposing to the right, using the raw histogram, should I be trying to get as close to the far right of the histogram as possible, or as close to the first set of vertical dashed lines to the left (which is just about in the middle)?

Are you talking about in camera or in post?

In post. In the raw histogram in RawTherapee. My camera (Nikon D90) would be working off the jpeg, wouldn’t it?

Expose to the Right is a technique for making exposures with your camera, not a technique for post processing.

In post, you should make the photo look how you want. For an “average” scene, a good technique is to try and stretch the histogram maximally, while avoiding any clipping of highlights or shadows.

OK, sorry. I misunderstood your question. Let’s say I’ve a number of shots of the same scene at different exposures. What I’m referring to is using the raw histogram in post to select the best exposed shot to work on. In this instance, using the raw histogram, should I be aiming for the extreme right of the histogram, or the first set of vertical dashed lines to the left (it’s roughly central in the histogram)? Are the dashed lines one stop apart?

What I look for when selecting from several different shots is:

  1. No highlight or shadow clipping
  2. Histogram that covers the most range
  3. If those two are equal, then different light conditions (I shoot a lot at sunset, the light changes quickly)
  4. Minute differences in the scene (things shifting in the wind, different glare, etc etc)

Oh, dear. I’m afraid I’m not explaining myself very well! I’m specifically asking about the raw histogram in RawTherapee. In order to avoid over-exposure should I use the right hand edge of the histogram or the dashed line to its left?

I just opened a raw I know has clipping in RT, and the raw histogram shows that stackup at the right hand edge. Anything below that would be usable data, so I think you want to use the right-hand edge.

Thanks, Glenn. Are the dashed lines a stop apart, as far as you know?

The raw histogram is linear, so the middle line is 1 stop down from the max, and the left line is 2 stops down from the max.

Can “Eposure to the right” be used for in camera and post adjustments?

Until now, I thought it referred to a technique used while shooting…

ETTR itself is pretty meaningless in post.

You look at the raw histogram in post to (as the original question asked) judge which pictures to process, and also to guide your shooting technique.

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On histograms (also relevant to post-processing):

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@pauld start by reading the documentation:

I did, Morgan, but it didn’t answer my question.

Thanks for your help.

It’s in there, just a bit hard to find. Under “Raw Histograms”:

The right end of the histogram is anchored on the white level

It might help your understanding to take a test photo that is completely overexposed (all pixels clipped) and then examine its raw histogram.

Thanks, Ed. Just did it. Clips at right hand edge. Thanks for the practical solution!

Raw histogram is nice but darktable and FastRawViewer can show you raw-overexposed areas and the info about clipped channels – can be handy as well: