A while back:
Gear P0rn - post it if you got it. - Page 539 - PentaxForums.com
I mentioned the Auto-Up Super Nooky I got for my Kodak Retina.
It's basically a close-up lens matched to the camera attached to a similar close-up lens matched to the rangefinder...
The idea is that focusing the rangefinder through the close-up lens corrects the parallax used by the rangefinder at the same rate as the focus on the taking lens.
I tried it on a pre-war Retina I have with the f2.0 lens, but I didn't have great luck (there were some wildly expired film issues there, too).
I recently got my Retina IIc back from service and gave it a try, with much better results. Fresh Ektar and the coated f2.8 lens probably helped.
Here's an example that sums it up pretty well...
The big two things two notice is that the focus is off... and the framing is not quite right... so it isn't perfect.
I'll note this was handheld at f4 or 5.6, so not ideal conditions for macro with a vintage rangefinder.
The focus may have been me... leaning over like that handheld I probably wavered the half-centimeter or so of the missed focus...
The framing also needs to be corrected a bit... the Super-Nooky does not completely fix that.
But it's sharp enough, and everything else works... so I'll give it another try on the next roll.
-Eric