My local shop had a somewhat stiff but decent looking Zeiss Jena 180/2.8 in Exakta mount (serial number suggests about 1947) and after it sat around for some months, I found myself unable to let it languish, so lighter by ten bucks, I figured I ought to be able to do something with it, at worst fire up my old East German Exakta and expose some film. But when I got it home, I realized that the adapter is wonderfully simple in design. Photo should show this. It's a piece that's just spigoted into the body of the lens, and held on by a threaded collar, so the adapter itself needs no threads. So I rummaged in my scrap pile and came up with an aluminum piece - I think it was originally a hub from some long ago film processing equipment - that I was able to machine down to make a Nikon mount, with the bayonet from some now forgotten broken lens. Given that the register distance of the Nikon is only about 1.8 mm. different from the Exakta, there's plenty of room.
It's not killer-diller sharp, but not bad, though pretty hard to hold given how big and heavy it is. But anyway, I was able with a little fiddling to get it to focus to infinity, and got the focus and aperture limbered up enough to work, though still tight. I shot down toward the backyard pond, handheld, and at least came up with an image. More experimenting in daylight conditions is called for, and maybe some focus fine tuning, but it seems promising, despite being a little long for use on DX. It is, if nothing else, a very impressive hunk of glass!
