Why does my new Canon Ixus 55 only seem to allow "film speeds" of 50-400. Wouldn't it be easy to allow a much wider range that would offer much greater flexibility? Hannah Chiswell
It would -- but the image quality would suffer. In normal photography, a slow film needs more light than a fast film, but a slow film usually provides much better image quality: pictures taken with fast films usually show grain. With digital cameras, faster "film speed" settings don't produce more grain but more "noise". This can be very visible in clear areas such as sky. To get more speed, you need a bigger sensor, which can collect more light. This is why pro digital cameras usually produce better results than the snapshot types, even if the number of megapixels is the same.
