What does “dynamic range” really mean for cameras in real-world photography?

Question

I’m trying to reconcile sensor specs with what I actually see in the field. I understand that noise, sensor design, and resolution all affect image quality, but I want to focus specifically on dynamic range.

For example, my experience with a Canon 5D Mark II is that usable range in a single exposure seems much lower than some broad claims that “digital cameras have more dynamic range than we need.” I often see different ideas mixed together: total dynamic range, tonal range, signal-to-noise limits, and what detail is still recoverable in shadows or highlights.

When people say a camera has a certain dynamic range, what exactly are they referring to in practice? How does that differ from human vision, which seems able to handle a much wider range because our eyes and brain adapt over time? I’d like a plain-language explanation of what camera DR means in a single exposure versus what we perceive by looking at a scene.

user45637 · Answer

I am not familiar with the terms of 'tonal shift range' and 'detail range'. If I understand your question correctly I'd like to adress the dynamic range part of it however.
First of all:

Dynamic range, abbreviated DR or DNR,[1] is the ratio between the largest and smallest values of a changeable quantity, such as in signals like sound and light. - https://en.wikipedia.org/wiki/Dynamic_range

Now for the eye we are talking about a combination of eye and brain which basically does aperture bracketing automatically all the time, while the brain creates an HDR image of the scene for us. Wikipedia references 10-14 stops for that, however with longer adaption time (think of going from a brightly lit room outside directly and after 30 minutes of waiting outside), your value gets more correct (It should be something in the twenties). This very nice thread on our photo-stackexchange covers more than I am capable to say from the top of my head: How does the dynamic range of the human eye compare to that of digital cameras?

The value that is referenced when one speaks of

that digital cameras have more DR than we need for a high dynamic range scene

is the dynamic range (nothing fancy to add). You have to differenciate however of the DR your camera is capturing, and the intensity variation which the scene displays. If you photograph a forest against the sun, the DR of the scene is incredibly high and your sensor will not capture brightness differences in the shadows and/or in the highlights at some points of the image. If you take an image of a white bedsheed that is equally lit, the dynamic range can be under a stop and your sensor will not have any problems capturing the brightest and the darkest part of the scene.

The following question should be: which dynamic range does a typical "high dynamic range scene" have? In my opinion a highly philosophical question, also depending on what your typical subjects are. For landscapes, I would regard this to be an evening, close-to-sundown situation as often photographed, and just by a guess I would say that the DR in the scene will easily overcome 15 stops, which a modern sensor cannot cover.

What does “dynamic range” really mean for cameras in real-world photography?

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