As far as I'm aware, most if not all DSLR's use a sensor with an aspect ratio of 3:2 whereas compact cameras and most Compact System Cameras use a sensor with an aspect ratio of 4:3. Presumably the aspect ratio of 3:2 is a carryover from the days of 35mm film. However why is 4:3 used for the compacts ?
A couple of contributing factors I've read about are
- Until 16:9 widescreen came along, 4:3 was the stanard AR for TV and monitors
- A 4:3 AR is more economical because it is "squarer" and hence for a given pixel pitch and total pixel count, the diagonal of the sensor is smaller. This makes lens design more economical and keeps the marketing peple happy with a nice large pixel count.
But maybe there are other factors ? I've seen some people advocating square sensors but I can't see that being accepted in consumer cameras. Any thoughts ?