KOMZ Jupiter-11A 135mm f/4

A Jupiter-11A gives you one aperture ring and nothing else. No preset collar, no pin, no automatic stop-down. You focus at f/4 with the finder as bright as it will ever be, then turn that ring toward f/8 or f/11, and the screen dims as you go. On a Zenit, whose screen is not bright to begin with, that last adjustment happens half blind. Before you think about sharpness or bokeh, that is what living with this lens is like.

Underneath is a Sonnar derivative with four elements in three groups, the same layout as the prewar Zeiss 135 it copies. Only six air-glass surfaces, though a hood is still worth fitting over the 52mm thread. KOMZ, the Kazan optical plant, built this A version with a removable mount adapter, usually supplied as M42. That is why the lens shows up on Prakticas, screw-mount Pentaxes and Zenits, and why putting it on a mirrorless body takes nothing more than an ordinary M42 adapter. Arsenal's Jupiter-11 Automat shares the name but not the mount: a separate bayonet lens made from 1969 for the Kiev-10 and Kiev-15. It will not go on an M42 body, so read listings carefully.

The iris has twelve blades. Anywhere from f/4 to f/22 the opening stays close to a circle, which keeps street lamps and backlit leaves behind a subject looking like round discs rather than polygons. It is a pleasant trait, not a promise of smooth backgrounds; how the blur looks still depends on distance and on what sits behind the subject.

Sharpness is where the factory figures speak plainly. The spec was 42 lines per millimetre at the centre and 29 at the edge, which puts the edge well behind the middle of the frame. Shoot it with that in mind. A head-and-shoulders portrait or a single figure pulled out of a crowded market puts the important detail where the lens is strongest, and the softer margins fall into background anyway. Architecture shot square-on, with fine detail running into all four corners, asks for what the numbers say it does not have.

Among the other Soviet 135s, the trade-offs are concrete. The Jupiter-37A adds a preset ring, which lets you stop down to a chosen value without taking your eye off the finder; the 11A has only the one ring. The Tair-11A is a stop faster at f/2.8 and a much larger, heavier lens to carry. If a 135 rides as the second lens in a shoulder bag, the slower Jupiter is the easier one to keep with you. Metering takes care of itself if you stop relying on the camera for it. Read the scene with Zone Light Meter in your hand, focus wide open, then set the f-number the app gives you on the ring. The camera's stop-down metering never enters into it, and the finder only goes dark at the moment you are ready to shoot.

A Jupiter-11A is usually the cheaper lens to find than a Pentax SMC Takumar 135mm f/2.5, and the Takumar is more than a stop faster, so the choice comes down to budget and how often you shoot in poor light. Before paying, close the iris through its whole range and look at the blades. They should move smoothly and show no oil, because an aperture that sticks on a manual-only lens leaves you with no workaround.