I feel like everyone is conflating dynamic range (range of light values available to the sensor) and SNR (signal to noise ratio).
Above or below your sensor's native ISO sensitivity, you're at the mercy of your camera's processing circuitry, either to boost sensitivity or reduce it. The further you push the gain, the more noise is introduced by amplification, which interferes with dynamic range, but doesn't *restrict* it. Your high-gain images will appear to have less dynamic range, but the sensor will still record the scene is within its available range. Trouble is, that range is 'washed out' by the noise being added to the output. It's like sitting in a noisy room, where your ears might be hearing the full range of your friend's voice, but you might miss inflection or tone because the noise floor is too loud, and on the same frequencies you're listening for.
You get noise from other sources on longer exposures, because the sensor in your camera is sensitive to more than just visible light, and you start getting into more esoteric categories of noise like shot noise and photocell leakage current. That's mostly a problem for astrobois though.
Maximizing dynamic range in your finished images is a balancing act of staying close to your sensor's native ISO, and keeping exposures within the available detection range of the sensor. If there's too much contrast in the scene, you have to bracket and stack. That's just physics.
>>3964375Has the best suggestion. Get to know your gear. Every body will have its own range of useful sensitivity before the noise floor starts to interfere. Use that range to balance shutter/aperture and avoid clipping, and you'll get the whole scene, if it fits in your sensor's bandwidth.
