This lens is collapsible.

Focal length: 50mm
Mount: M39
Aperture: F 2.0 - F 16
Min focus distance: 1.0m
Length: 24mm collapsed, 43/47mm [+ 11mm for the adapter],
tube protrudes 17mm to the back when collapsed
Diameter: 48mm
Weight: 202gr.

Some pictures:

A7 and the lens, collapsed

A7 and the lens, extended.

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 the satellite dish to the right of the big solar panel near the center of the photo.

F 2.0. ISO 100.

F 8.

F 16.

Closest focus  is 88cm from the outermost edge of the lens, F 8. Focus on the program wheel of the camera.

This lens has had an accident, the front lens couple has separated in a large area, visible on the photos. I would have re-cemented the couple, if I found a way to take the couple out of its ring. The ring unscrews easly, but the couple has been pressed or peened into the ring. No way to get it out at reasonable cost. Any proposal would be welcome. So it's tested with its flaws.

The picture results have stunned me. There is a soft area, like an overcast, down to the right. But the rest is still much better than I thought. Wide open it's a bit soft at the edges, but it's perfectly usable. Stopped down it's sharp.  Its contrast is astonishing for an old and battered lens. The lens has no close focussing capablities. It is very small and lightweight, particularly for a F 2 lens. A nice old lens which offers one usable stop more than a standard lens.

This lens is collapsible. There is enough room inside my camera to collapse it, it doesn't collaps as far as some other M39 lenses, but you have to act at your own risk. Please proceed slowly, you don't want to aspire dust into the camera.