Camera College
The complete guide to modern photography
image. Increasing the ISO will amplify the noise as well as the signal, for instance. Some cameras are better performers at high sensitivities than others, and both the size and the pixel density of the camera’s imaging sensor can play a part. Essentially, the smaller and higher resolution the sensor is, the sooner the effects of noise become apparent at high ISOs. A large sensor combined with a low resolution tends to give cleaner results at these sensitivities.
Take a current low-light champion: the Sony Alpha 7S II. This full-frame camera offers a paltry resolution of 12.2MP, but a sensitivity range that expands from a maximum ISO 102,400 to ISO 409,600.
The majority of cameras are capable of delivering low-noise results up to ISO 800, with an acceptable amount of noise from
ISO 800 to 3,200. Things tend to get progressively rougher beyond this, but high-ISO noise reduction can help to temper the increase in noise, in JPEGs at least.
Camera-based noise reduction can be rather a blunt tool, softening both the noise and the fine details. You get more freedom to adjust the strength of the effect to a greater degree in photo-editing software, as well as selectively applying it to different parts of an image.
Long exposures can dish up more digital artifacts too, as the sensor heats up during the exposure. This is made worse if you’re shooting in a warm environment or you have been recording video prior to shooting. Long-exposure noise reduction can help with this, but it doubles the length of time it takes to save an image to the card.
Where grain can add to the mood of a picture, noise can simply leave you in an ugly mood, such is its rather artificial look