Understanding photo Resolution

Photo resolution is a feature that confuses many. This shouldn't be so because the resolution of a camera is the physical number of pixels on the sensor. That only changes when you physically choose a different picture size from the camera menu—or if you crop the file using software.

To be pedantic, 'resolution' is not just about the number of pixels in the camera, although this is very important. Resolution is also influenced by the quality of the glass elements in a lens, the camera's image stabilization technology (indirectly), the use of a lens hood (indirectly) and the shooting technique employed by the photographer.

So, let's look at just the numbers. An Olympus OM1 sensor measures 5184 x 3888 pixels. Multiply these two numbers and you get 20.1 megapixels. Olympus, like every camera maker, quotes an 'effective' resolution, in this camera it's 20.4 - but because pixels around the...