What is the histogram for?

[stolzy]

I'm perplexed as to the value of the histogram for judging exposure.  Everywhere I read how useful it is for nailing exposure.  However if I have a scene correctly exposed, changing the exposure by, say 6 stops over or under changes the histogram not at all.  If I take the three pictures, one is grossly under-exposed the second, perfect and the third completly blown.

What is the value of the histogram for exposure?

[BobD]

So happy to read that someone else finds histograms to be of no use.

[BobJ]

I don't understand at all why your histogram is not changing with exposure - it does on my cameras. There is something  wrong. The little histogram that you can have in the corner of the viewfinder is of little value - it's too small. If, like on my x-t5, you can have a full histogram with all three colour channels showing, assign a button to it. The resulting histogram is accurate for the jpeg only. The right hand highlight end is fairly accurate for raw, although you may squeeze out another half stop. You cannot recover blown highlights, so make sure the  right hand side is not bunched up against the limit. Also remember, that if there are specular highlights in the picture, such as sun on water or mettalic surfaces the highlight end will show a narrow peak, which in this case, will be OK.  For raw you can pretty much ignore the shadow clipping as the shadows will be recoverable, unless they are really dark. The histogram is of great use when taking landscapes with a tripod. I use it frequently. It tells me when I need a separate exposure or grad filter for the sky. Of course, you wouldn't use it for street!

[Paul Szilard]

I find the histogram most useful to judge a luminosity distribution of the image. If I turn on the blinkies the I can easily sport any blown highlights and make exposure adjustments accordingly.