Over the last couple of days I was thinking about noise that's generated in digital photo files, and was wondering if longer exposures at lower ISO gave more or less noise than a shorter exposure at higher ISO ratings, assuming the overall exposure is the same in both instances. It seemed like a good idea for some testing.
Now, just a few minutes ago, I came across this comment: I believe (he) means that he's set the camera at ISO 400 and then (using the exposure compensation feature) deliberately underexposed 2 stops... thus yielding the same exposure as if the ISO had been set to 1600 to start with. Then, plus two stops of compensation is applied during "development" (the conversion of the RAW data) [...] With some digital systems [...] it tends to yield a bit more noise (the digital equivalent of grain) than with the (camera's) native ISO 400 setting, but much lower noise than obtained by using the (camera's) native ISO 1600 setting. So [...] it's a way of increasing the quality of shots at higher ISO's. Well, I'm no expert on such matters, but I tend to believe what I see, so i did a quick test. Unfortunately, the light was changing rapidly, and it might be better to try this when the light is more stable. However, this first Q&D experiment seems to indicate that lower noise is observable using this technique. But don't take my word for it, try it yourself under stable lighting conditions, and see what results you get. Shel
