We all noticed that our digital cameras offer a button (or a menu) to choose different sensitivity ISO settings. The casual user would note that the higher this value (let’s say 800 or 1600 ISO), the easier it is to snap a photo in a dimly-lit roomÂ or to stop the motion of a fast moving model (like kids, for example).
So, why not always set the higher possible ISO?
Actually, there is a big disadvantage to it. The higher the ISO setting, the worse image you get. Like for analog film cameras, high ISOs mean that the technology has to grab more information out of less light. The digital camera sensor needs as much light as possible and setting a high ISO just means that the sensor has to amplify the image more. Just like a relatively bad HiFi equipment, the higher the volume the more noise you’ll get. In film cameras, it meant grainy pictures.
In digital images, noise is this grainy slightly colored spots that appear all over the image and most spectacularly in the dark areas. In small compact cameras, 800 ISO may be much more than what we would accept as reasonable. Often, 200 ISO is a maximum acceptable level. In most Digital Single Lens Reflex (DSLR) cameras, 800 ISO is nearly always Ok. 1600 ISO may be usable but it’s not sure you’ll appreciate fully the resulting images.
So, I keep my camera locked to the lowest ISO setting (100 ISO for my Konica-Minolta Dynax-Maxxum 7D camera). I only go higher if the image cannot be shot any other way and I know for sure that the noise will only be a small inconvenience (small size prints, not trying to do artsy photos).
It’s your choice, now.