This is a rare lens, usually made for the Exa in Exakta mount with a lightmeter screwed to the top. I found one in M42 mount for the Edixa. I haven’t used it much, but it is definitely an interesting tool for bokeh photography. The look is similar to the famous Meyer Domiron 50mm f2.0 lens, and in fact it seems to be a double gauss design, like the Domiron. While the bokeh is not quite as sharp-edged as that of the Domiron, the lens is actually sharper and contrastier than its much-more-expensive cousin. This is an excellent lens, and one to look out for.