Dynamic range is the ratio between the strongest and weakest signal measured in a given context. For example, the dynamic range of a camera sensor is the ratio between the brightest and darkest signals that can be captured in a single image.
Like most other things in photography, dynamic range is often measured in stops, with one-stop brighter meaning twice as much light.
The human eye can actually adapt to different brightness levels in the range of about 46.5 stops.
Dynamic range & ISO settings
The dynamic range of your camera depends on the ISO setting. For example, the Sony A7IV as measured by DXOMark has a dynamic range of 14.7 stops at base ISO but only 10.2 stops at ISO 6400. Typically, the highest dynamic range is obtained at the base (non-extended) ISO.
Dynamic range & Sensor Size
We also see that dynamic range increases with sensor size. Therefore, it will be easier to capture the dynamic range of a dramatic landscape with a larger-sensor camera with just one shot, which is one of many reasons why full-frame cameras are often preferred for landscapes.
These days, any current full-frame camera will give you a healthy number of over 14 stops. Moreover, there are so many other factors affecting image quality that sensor dynamic range should not be overemphasized
Underexpose for Digital & overexpose for Film Cameras
For digital cameras, shadow details are easier to recover compared to highlights ie underexposure is easier to recover than overexposure. This means that you should expose to the brightest important parts of your image without being overexposed. Moreover, for landscapes, you should do this at base ISO (except when you can’t).
In the film, the situation is a little different. Overexposure is more easily recovered with negative film, whereas shadow detail is very easily lost. This is the opposite of digital, where highlights are easily lost but shadow detail is easily recovered.
Therefore with negative film, it makes sense to overexpose a little to get the additional shadow detail. Please note, this does not apply to positive or slide film which loses detail in overexposure like digital.
Dynamic range simply tells you how great the difference is between the brightest and darkest signals, either in a scene or perceivable by a sensor. In some types of photography such as landscape photography, the dynamic range of scenes is often high, and therefore it’s important to fit as much of it in your final image as possible.