The 30% maximum theoretical difference between 85mpx and 51 mpx (or 5% between 45 and 51), requires lens that can out resolve 45mpx of which their are likely none in the UWA 17mm range that I prefer.
While not ideal, you can get an idea of how current EF lenses will perform at around that FF sensor resolution by trying them on a 90D or M6II. Of course you will only be able to judge central sharpness and edge performance will remain somewhat unknown (but can probably be estimated from your experience with them on the 5DsR).
To paraphrase RC at Lens Rentals: even a not so good lens will look better on a higher resolution sensor. Go to the appendix at the bottom of this post.
Basically you're concerned about system MTF, and to determine it, you multiply lens MTF by camera/sensor MTF. So, system MFT will still improve with an OK lens on a higher resolution sensor. Sure, system MTF will improve even more with a higher performance lens.
If you want some numbers, watch the following video presentation by Peter Karbe, Leica's chief lens designer. Specifically at around 1:17:00 (one hour, 17 minutes). He talks briefly, with numbers, about determining when a lens or the sensor limits the other. Basically, if the lens is less than 50% MTF at half the sensor's Nyquist frequency, then the lens is the limit. If it's higher, then the sensor is the limit.
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gdanmitchell wrote:
I use a 5DsR, and I can't see that it would make sense to move the R5 for me. I can already produce excellent large prints with the 5DsR files and, as you point out, it works pretty well for the kinds of wildlife photography I do. Plus, I'm invested in a slew of EF lenses, and if I'm going to make a move I'd rather do it wholesale.
I'm curious why you feel you a gradual transition wouldn't work for you? I.e. new R body with your existing EF lenses. Sounds like you'd want to switch over to RF lenses at the same time.
Jul 13, 2020 at 12:00 AM
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