Making Sense out of Sensor Sizes

--by David Cardinal

It has become almost impossible to actually figure out how big a sensor is, or how long a lens is, just by glancing at the specs. For most of the photography industry, for many decades, 35mm was more or less the norm. By definition that meant a standard size film negative, about 35mm by 24mm – corresponding to today’s “full frame” sensors – and a simple measurement of focal length for lenses could be read right of the lens as a result.