Pixel Density on Digital Cameras

Bill Creech compiled that chart and posted it over at Digital Photography Review forums.

Camera makers have been pushing more and more megapixels onto their cameras. That’s because camera buyers – confused by cameras in general and even more confused by digital cameras – have been conditioned to use megapixels as a measure of camera quality.

All things being equal, more megapixels don’t hurt. What the chart makes clear is that more and more pixels have been crammed onto the same size sensors. (The sensor is the chip that converts light into electronic signals.) As the pixel density increases the picture tends to get noisier. The noise is especially noticeable at higher ISOs. Cameras use high ISOs when less light is available, so the effect is most often seen with pictures taken indoors or at night.

A better measure of quality is sensor size. More expensive cameras have larger sensors. In the chart above the cameras marked DX and FX under sensor size are Nikon’s DSLRs. The FX sensor is the same size as a piece of 35mm film. Note that Nikon’s recently-introduced, top-of-the line D3 and D700 have the largest sensors and lowest pixel density in Nikon’s lineup. They can also achieve the highest ISOs – up to 6400 on the D700, with a “boosted” value (whatever that means) of 25600.

The non-DX and FX sensors in the chart are less expensive point and shoot camera sensors about the size of your pinky nail.

See also:
- The Megapixel Myth (KenRockwell.com)