ROBOT Zeiss Tessar 1 : 3.5 f = 3 3/4cm

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

Focal length: 37.5mm
Mount: Robot M26
Aperture: F 3.5 - F 16
Min focus distance: 0.45m
Length (from flange): 17/20mm [+ 13mm for 2 adapters]

Diameter: 44mm
Weight: 118gr.

Some pictures:

A7 and the lens.

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 out of the window of my holiday home on a dull day, so there might be blur by shake, especially at F16.

F 3.5.

F 8.

F 16.

Closest focus (F8) is only 39cm from outermost edge of the lens. Focus on the program wheel of the camera.

This lens does hardly cover 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 lens is very small indeed and has a multi-blade iris, perfectly round. It has click-stops for distance settings. According to the serial number, this is a very old lens, made in late 1941. As you can see on the sample pictures, there is vignetting and softness towards the edges in full format, not visible on the 24x24mm Robot cameras. As on many very old lenses contrast isn't terrible. The Robot is built for hyperfocal use, so this lens is perfectly designed: it's sharpest at F 8. The lens has very good close focussing capabilities.