Who Cropped My Sensor?

Today’s Post by Joe Farace

For reasons that I don’t understand, the term “crop sensor” gets tossed around by people on the Internet when they refer to digital cameras with sensor sizes smaller than 24x36mm. Unlike Who Shot Roger Rabbit, it’s why somebody cropped my sensor. It’s as the format that Oscar Barnack created for the first Leicas in 1925 was some kind of Holy Grail of imaging. It’s not. The first Leica used 24×36 but others, including the Olympus Pen used 18x24mm and early Nikon, Minolta and other Japanese rangefinders adopted 24 x 32mm before standardizing pm 24x36mm.

When Oscar Barnack  developed the camera that came to be known as Leica, he wanted to use movie film sideways doubling it’s 18x24mm format to 24 x 36mm. One story about the 35mm motion picture film format, perhaps apocryphal but still interesting, was that when Thomas Edison was asked by his workers how wide to cut the film, he held up his thumb and forefinger and said “About this wide.”

What’s all this got to do with sensor size? Nikon’s D1 was introduced in 1999 with a 23.7 × 15.6mm sensor. When Canon introduced the D30 in 2000 using its 35mm film camera lens mount the sensor size was 15.1 x 22.7mm. Nikon insisted that 23.7 × 15.6mm was adequate even after Canon introduced a full frame EOS-1D in 2001 and didn’t joint the full-frame parade until 2007’s D3.

PanasonicGM1zoomlensOlympus, much like Sony, was always willing to go their own way and introduced their Four-Thirds system at photokina and I was there at the launch looking at a wooden prototype while listening to a German professor explaining why 18 mm×13.5mm was the “perfect sensor size” for digital imaging. The Four-Thirds system is dead but lives on in  sensors used by Micro Four-thirds system cameras from Olympus and Panasonic.

Some people, like my friend Jack, thinks the term “mirrorless camera” is synonymous with Micro Four-thirds but it’s not. Some mirrorless cameras use full-frame sensors, others use what’s called APS-C or 23.5 x 15.6mm format. (For younger reader that refers to the Advanced Photo System launched in 1996 and was an experiment in film format but before it could catch on was overtaken by digital capture. APS had the advantage of using multi-format capture, including APS-C or 25.1 × 16.7 mm, which as you can see is not the same as what digital camera makers call this very same format.

And so, dear readers what does “crop sensor” mean? If film shooters can refer to roll film capture as 6×6, 6×7, and 6×9 and sheet film as 4×5, 5×7, and 8×10, why can’t we refer to the sensor size by its actual measurements because as you can see, their ain’t nothing standard about ”crop.”


Barry Staver and Joe are co-authors of Better Available Light Digital Photography that’s currently out-of-print but while new copies are available at collector (high) prices you can purchase used paperback copies at giveaway prices—less than seven bucks—from Amazon.