I'm not good at tests, like ya'all are. Over at the Pentax place I hang at, though, they asked about guilty pleasures last night and this was my response...
"I haven't been a Pentaxian long enough to have a guilty pleasure here yet.
But let me tell you a story... I have an uncoated 1937 Zeiss Sonnar 50/2 in a collapsible mount that was originally made for the Zeiss Contax II rangefinder. This pre-World War II lens was the middle of the road lens - not as fast and expensive as the Sonnar 50/1.5 but still a step up from the Tessar 50/3.5 and could be collapsed into the body to make it easier to carry around. Zeiss was, of course, the primary competitor to Leica and their rangefinders.
After the war, Nikon started making their S series of rangefinders. In many ways they took what they saw as the best ideas from both Zeiss and Leica and combined them in one camera. When I bought a S2 rangefinder, a friend of mine offered to sell me that Sonnar 50/2 tweaked to work on the Nikon standard.
Sometime later my S2 developed trouble and while waiting for it to be repaired, I bought an Amedeo Adaptor to be able to use my Nikon S mount lenses on Leica M mount cameras.
SO - I can take a lens made in 1937 for a Zeiss camera, modified to work on a post war Japanese camera and use it on a 2012 made German Digital Camera, my Leica M 240, with results like this:
View attachment 4862382
That's my way of testing things
😉