Whenever articles about digital sensor equipped backs adapted to older SLRs are published, I quickly run through in the hope that I'll see my 1970 vintage Canon TL listed as one for which a digital back is now available. Alas, to this date I have not seen even a serious suggestion that such a back will be developed for those old Canons.

It would be good fun to see just how usable that match-needle metering, split-prism ground-glass center circle manual focus Canon camera and the two Canon FL lenses (50mm f/1.8 and 200mm f/3.5) would be with aged, but surgically enhanced (cataract surgery), eyes. The camera and lenses were last used early in this century, to very good effect, by my daughter when she took a basic-equipment-specific photography class pertinent to her Georgia Tech Masters in Industrial Design (Go It You Ramblin Wrecks)

I suppose that this is a vote for yes on 'Equipment Counts.' The Canon TL camera, 50mm f/1.8 FL and 200mm f/3.5 FL lenses made a pretty good rig in the early '70s. If nothing else, that camera would resurrect some rose-tinted memories of youth in Sunny Southeast Asia in the early 1970s.

My daughter had her choice when I got my D7100; she chose my D80; I sold my D300 to help finance the D7100. I now have a D850. However, I use the D7100 regularly. The attached image was taken with the D7100 and 18-70 kit lens that came with my original Nikon DSLR, a D70s. I have started using the D7100 for some video work; usually will mount my Nikkor 28mm manual focus prime and shoot some video or stills with that combination. It's is a lighter combo than a 24-70 on the D850 and some days I do not feel like carrying the extra weight when I am OK with the results from the D7100. IF it is a serious shooting day for me, I have the D850 with 24-70, and mount a 70-200 on the D7100. I really do not like changing lenses if I can avoid it especially in the field. For low light work, for sure the D850.

I disagree. It's not simply all about the optics these days. That may be true with film cameras but there's way more to it with digital cameras. Film cameras must work with the light available to them, but digital cameras have electronics on their side.
Optics are very important but so is the image sensor and most important, the digital image micro processor.
I can put my EF 28-300L lens on my Canon 10D or my M50 or my 5D mk IV or my 5DSr. Do you believe the IQ will be exactly the same because I used the same optics?! No, it definitely will NOT. In digital photography it not just about the optics, it's about the whole camera.