Originally posted by lightbox No arguments, there. I was just wondering if maybe by focusing effort on a single line of lenses for both camera types they could achieve some kind of happy medium? Or is the idea of a small and light FF lenses just a pipe dream?
The DA 35, 40XS and DA 50 1.8, FA 31 ltd, FA 43 ltd and FA 77 ltd are all small ,light FF capable lenses.
The focal length of a simple lens, is the distance from the optical centre to the focal point.
If you look at the above and Imagine different size sensor at the focal plane, you can see that the larger the sensor, the more FoV is going to be captured. So the larger the sensor, the wider the FoV. A 50mm is a short tele on an APS-c camera, a Standard lens on a 35mm sensor, and a wide angle on an MF sensor.
Where the equivalence thing works in your favour is weight. A lens projecting a smaller image circle can be smaller, but also, when discussing FoV, when you go to 600mm FF to get the equivalent FoV to 400mm APS-c, the 600mm lens will have a lot more glass, be much more costly, will be a lot heavier, to get the same FoV. At the short end, people claim there is more distortion with APS-c. But the arguments have been theoretical and to my mind inconclusive. In the shorter end, sure a 35mm lens, standard on APS-c is theoretically smaller than a 50, but if you actually hold one or the other, you don't really care. The difference is insignificant.