Originally posted by aslyfox [ BTW, my wife has been very nice to me and allowed me to get good equipment and cameras ]
My wife is into photography and steals my favourite lenses for her own use. You have no idea how lucky you are.
Most lenses are sharpest in the centre and weakest on the edges, so the crop will use the sharpest part of the FF lens.
Canon EF 35mm f/1.4 USM L II on 24 MP APS-c
Canon EF 35mm f/1.4 USM L on 21 MP FF
I know these are not exactly the same lens, but it illustrates what I'm talking about.
Look at the FF edges compared to the APS-c wide open. The APS-c cuts off the worst part of the image. And the end results are very close in terms of utility.
For the most part FF lenses do very well on crop sensors. When you look at my DA*55 1.4 and DA*60-250, some crop sensor lenses also do very well on FF. It's more about the lens and the size of the image circle, than it is about what they were designed to go on. The DA*200 was never redesigned for APS-c. It went from being an FF lens in earlier incarnations, to being a crop lens, then back to being an FF lens, with very little modification in the various incarnations.
I you want the best edge to edge performance an that is worth more to you than the extra resolution, 1.4 (or even ƒ2) on APS-c is the superior image.
If you think about it, if I mounted the above lenses on my Q-S1, 1:2.3 sensor, only using the very centre of the lens, it would be by far the most consisted edge to edge, and possibly the sharpest image.
The edges on most FF wide angle lenses are extremely problematic wide open.
Last edited by normhead; 02-12-2021 at 09:54 AM.