On this B&H video (made by Kelby Training) photographer Larry Becker talks about the different camera sensor crop factors and their effects on your photography.
Only last week we published here the previous video in the FocusED series with Becker looked at camera sensors and this shorter video looks specifically at the topic of crop factor.
The concept of crop factor is both simple and complex. The simple part has to do with the basic nature of crop factor – on the most basic level a crop factor is a size ratio – if a full frame sensor (36 x 24 mm) is our basis (crop factor of 1) than anything smaller has a larger crop factor (APS-C sensor is 1.5x and micro 4/3 has a crop factor of 2x – your smartphone will typically have a 7x or more crop factor). It is also worth mentioning that anything larger (like a medium format camera) will have a crop factor of less than 1x.
Understanding the actual crop factor is the easy part – what is a bit more complicated is understanding how it effects your image. What you need to know is that if you have a 35mm lens – using it on a full frame camera (1x crop factor) you will get an angle of view of 63 degrees – using the same lens on a camera with an APS-C size sensor will give you a 1.5x times narrower field of view.
This is the main reason why ultra wide angle lenses are made specifically for each camera format (an ultra wide full frame lens will typically only be a wide angle lens on an APS-C sensor). With telephoto lenses this issue is typically less relevant and the extra range can even be welcome (many wildlife and bird photographers use crop sensors for this reason).