New York Times - David Pogue on camera sensor size

David Pogue wrote an illuminating article on digital camera size, discussing how hard it was to figure out the size of a camera sensor, and why it mattered. A very good point. One of the things I like about the camera specifications listed at Digital Photography Review is inclusion of the sensor size in terms of area and pixel density. (Area is handy because bigger is better, but pixel density is more revealing in my opinion, because it incorporates pixel count. Lower pixel density is better.)

Pogue then goes on to laud several cameras as having larger than average sensors for their class, such as the Canon Powershot S95. They are very good cameras with excellent image quality, but the landscape is more complex than just sensor size.

For example, the Canon S95 (4x zoom range) has 23MP/sq cm, while the Sony HX5 (a 10x zoom camera) has a pixel density of 37MP/sq cm. Lower pixel density generally translates to lower noise and cleaner images in low light. For reference, a large sensor SLR camera like the Canon EOS 1-D Mk IV has a pixel density of 3MP/sq cm - and takes incredibly low-noise images in low light. It also weighs several pounds.

So while larger sensors have an advantage, buying a pocket camera on that basis leaves out an important dimension of flexibility - the lens zoom (focal length) range. Camera manufacturers use smaller sensors in compact cameras with large zoom ranges because a 'long lens' size is roughly proportional to sensor size. In order to make a pocket-size camera, they put a smaller sensor in the camera. For many users, living without a 10x zoom range greatly limits the shots which can be captured. In particular, travel shots and action shots can be tough with a 4x zoom.

The other part of the landscape which is changing is sensor design. Digital camera sensors have become much more effective at capturing clean photos in low light as the sensor technology has been refined. For example, the latest generation of Sony sensors utilizes their "Exmor" sensors, which improves sensitivity by putting the circuit wiring below the image-sensitive layer of the sensor. Even in low light (for example using ISO 1600), very satisfying photos can be captured relative to prior sensors, and the technology improvement can larger overcome the difference in sensor size between these compact cameras.

Before buying a camera, consider the kind of pictures you'd like to take (including zoom range), the degree of 'automatic' versus 'manual' control you prefer, and compare real photos captured by reviewers and other users. Try the "Comparison Widget" as a quick way to compare photos of different cameras side-by-side (for the cameras already reviewed.)