We regularly receive emails from readers confused as to the actual size of sensor used in digital cameras. Sensors (CCD / CMOS) are often refered to with an imperial fraction designation such as 1/1.8" or 2/3", this measurement actually originates back in the 1950's and the time of Vidicon tubes. Those who find the specification sheets for these sensors are then even more confused about the relationship between the fraction and the actual diagonal size of the sensor. Inside you'll find an explanation and a table of common sensor sizes. We'll be adding this information to our glossary for future reference.