What Does Optical Resolution Mean When Talking About Photography and Cameras?

When talking about cameras and photography the term ‘optical resolution’ describes the total resolution that a digital camera, or optical device such as a scanner is able to capture. The optical resolution is expressed in megapixels or MP, with each megapixel being a total of one million pixels. A camera with an optical resolution of 24.2MP therefore is able to record an image which contains a total of 24200000 pixels. Shot in an image ratio of 3:2 a 24.2MP image would have a resolution of 6016 x 4016  and a file size of over 50Mb!

The 5D Mark IV has an optical resolution of 30.4MP