I thought I’d write a quick post about this because it caused me some confusion recently while I was creating some resources on calculating field of view and angle of view for camera lenses. The calculations for this require the dimensions of a camera’s sensor, and while working on the data list for Canon lenses I couldn’t figure out why my numbers weren’t quite matching some of those that I had come across on Canon’s own website.
A little digging back through archives revealed to me that Canon actually uses three different sizes of APS-C sensor, although I wasn’t able to ascertain exactly why they would do this. At first I thought it must be a historical thing, and that perhaps they used to use one size of sensor, but had more recently switched a different size. In fact that didn’t turn out to be true, because at the time of writing this post, they actually have all three different sensor sizes on the market at the same time!
For example, the Canon 7D Mark II currently uses a 22.44 x 15mm sensor. The Canon 80D has a 22.5 x 15mm sensor, and the Canon 77D has a sensor that is 22.3 x 14.9mm. Given that the 7D Mark II is the highest price point amongst these three cameras, this isn’t anything to do with sensor cost; I don’t think.
In reality, you’d never notice a difference so small when it comes to real world shooting, but we all think of Canon’s APS-C format as having a 1.6x crop factor, and technically only the Canon cameras that have a 22.5mm wide sensor have exactly a 1.6x crop factor (36/22.5 = 1.6).
I realize this information has a very small usage case, in other words you have to be as big of a nerd as I am, but since I never found all of this presented succinctly anywhere else on the internet, hopefully this will be useful to someone else who might be left scratching their head when some numbers don’t quite add up 🙂
Canon APS-C Sensor Sizes & Crop Factor
|Horizontal Sensor Dimension||Crop Factor|