There are a number of interesting Russian lenses for bokeh fanatics, and one of the best and cheapest is this one, an 85mm f1.5 lens made for a night-vision device. There are a number of versions of the Cyclop, the most notable being this one and a 85mm f1.2 version. These come with M42 screw mounts, but some care must be taken, since both come in several versions, several of which have a long extension on the back of the lens, which must be removed to mount on a digital camera. Luckily there are versions of both that have a standard M42 mount. I prefer the f1.5 version, as the f1.2 version has serious vignetting and a lot of chromatic aberration, as well as being very soft off center; however these lenses are cheap, and I’m betting that the f1.2 version could also make some nice images, although I don’t have one.
The Cyclops do not have diaphragms, so always are at full aperture. There is a standard photographic version of the Cyclop f1.5 named the Helios 40-2, which does have a diaphragm but costs quite a bit more. One warning about the Helios 40-2 is that it comes in a new version, with Nikon and Canon mounts. This version seems to be optically better, but it does lack some of the very characteristic sharp-edged bokeh that I like so much. These lenses are, AFAIK, copies of the Zeiss Biotar 75mm f1.5, which costs much more and IMO does not really have a very different rendering.
