The APS-C sensors on Nikon, Ricoh, Fuji, and Pentax (maybe more) cameras are in the same 3:2 aspect ratio as full frame 35mm film camera frames and full frame sensors.
Half-frame film cameras are cameras with each frame in the same proportion as the whole frame (36:24) but with the long side vertical, so it is 24mm and the short side is 2/3 of that.
So an APS-C sensor and the area of a half-frame film are the same exact size.
In this diagram the pink shaded area is the frame size of a half-frame film camera. And if we were to turn it 90° it would cover the same area as the APS-C sensor.
Now, why am I amazed at this? Well only because it takes what I have always understood, a step further.
The first manufacturers in the serious digital space simply copied the 3:2 aspect ratio from film cameras AND what is more, for the actual size they must have copied the size of half-frame film.
After all they could have made the sensors in the same aspect ratio but with smaller physical dimensions. But they did not. They copied the exact dimensions of half-frame film cameras.
And why not because they were in new territory with digital sensors. Who knew how good they would be.
As it happens, they have much more acuity than film.
Canon Broke The Mould
Canon broke the mould. Their APS-C sensors are slightly smaller, being 1.6 times smaller rather than 1.5 times smaller than full frame.
That makes for some interesting steps up between say Nikon and Canon. For example:
Put a 50mm lens on a Nikon APS-C digital camera and it is equivalent to a 75mm lens in full frame (50 x 1.5)
Put a 50mm lens on a Canon APS-C digital camera and it is equivalent to an 80mm lens in full frame (50 x 1.6).
So the Canon sensor is a bit smaller but the ‘reach’ in full-frame equivalence is greater.
Leave a comment