ROBOT Schneider Xenagon 1 : 4 / 30 "spy" lens

This lens does hardly cover full format, it was built for 24x24mm square format.

Focal length: 30mm
Mount: Robot M26
Aperture: F 4 fixed
Fixed focus, min focus distance: ~2m
in reversed mount focus ~0,70m to ~3m
Length (from flange): 8mm
Diameter: 31mm
Weight: 41gr

Some pictures:

A7 and the lens.

A7 and the lens in reversed position.

Sample pictures: You may click on the sample image (except closest focus) for full resolution. The full resolution image opens in a new window, so you can keep it open for comparison. Focus is on infinity (except closest focus). These pictures are hand-held, the first out of the window of my holiday home. So there might be a little bit of blur from the absebce of a tripod.

F 4. Not the sharpness of the regular 30mm Xenon focussed, but a focus free lens is more difficult to build, it's a compromise.

The lens at about 3.5m. Quite o.k.

The lens at 3.5m in reversed position. A bit too far, the limit seems to be around 3m.

Closest focus in reversed position is about 70cm from outermost edge of the lens. The program wheel of the camera is at 60cm, the cap near the old Zeiss lenses is at 70cm.

Closest focus in normal position is around 2m from outermost edge of the lens. Focus on the program wheel of the camera. This is a crop from a larger image.

The lens flares a lot if there is sidelight. Just to show the effect, no full resolution image.

This lens hardly covers full format, it was built for the 24x24mm square format of the Robot cameras. The adaption to the A7 is easy, the focal flange distance of the Robots is 31mm. That's not far from the M39 which is 28.8mm. So you add a 2.2mm adapter to a M39 one and you are there. M26 to M39 adapters a readily available on the web and they can be cheap. The Robot lenses are relatively small and they are fine for APS-C.

This is an interesting lens. It's a 30mm F4 fixed aperture and focus free Xenagon lens. It's a "spy" lens, they called it "Beamten-Objektiv" (civil servant lens). It focusses from about 2m to infinity. The edges are soft. As it has a 26mm thread on both sides, the lens can be reversed. In reverse mount it focusses from about 70cm to 3m. With this lens, a 50 exposure wind camera and a cable release the camera could easily be hidden for spying purposes. These lenses have no markings, no manufacturer sign and no serial numbers. They are extremely small and light.

As you can see on the sample pictures, there is a bit vignetting in full format, not visible on the 24x24mm Robot cameras. Even the very soft edges would disappear. For a focus free lens with F 4 aperture it's fine.