I just tried comparing a full-frame 43MP Sony A7R3 and 135/1.8 Sigma lens bought for $1200 to a 16MP micro 4/3 Panasonic GM5 with an adapted FED 50/2.8 lens (E26m) obtained at a used book store for $4. Sony wins considerably on all counts other than size, which is to be expected. GM5 was obtained for the pocket camera role with a 20/1.7 lens.
135mm can be used almost directly into light sources. The 52mm, especially since it has wider coverage than needed, cannot — but its contrast improves greatly with a lens shade or a hand used as a gobo. Edge sharpness on the 52 falls off rapidly, even though only the center quarter of the lens area is used by micro 4/3 camera.
Conclusion: expensive modern lenses are better than cheap obsolete lenses. A real discovery, right? The purpose of my quest was to see if I could use the 52mm for stylizing 1930-1950s look in camera. The answer is “yes”, but focusing has to be done with great care. Even zoomed in, focus was difficult to obtain. The reason I was curious about the 52mm is that I started my photo learning on a FED camera with this or a very similar lens.