This is a topic that creates a LOT of confusion for people, and it’s about time we clear that confusion up. The question comes from Calvin Siew who says:
I know the fact that the focal length of full frame lenses will be factor by x1.6 when using a crop sensor camera. What about the aperture?
The fact is, the sensor size has NO impact on depth of field, and it has NO impact on how much light is gathered by the lens.
We see all sorts of talk about “full frame equivalent”, but here’s the problem. Full Frame is just an arbitrary comparison point. It’s become the standard by which all other imaging sensors are measured because a “full frame” sensor is the same size as a 35mm piece of film.
However 35mm is not “full frame” any more or less than a Polaroid photo is, or a medium format film like 4×5 sheet film.
35mm became the “full frame” standard because the film format was incredibly popular with the general photo taking public.
Now that we understand that the notion of full frame is arbitrary, we can look at the impact the sensor size has on your images, which I discuss thoroughly in the video.