Focal length: 50mm
Mount: Contax rf
Aperture: F 2.0 - F 22
Min focus distance: 0.90m
Length (see*): 23mm [+ 19/25mm for the adapter]

Diameter: 47mm
Weight: 120gr.

*Contax mount is quite different. In fact it's two mounts. The inner mount has a focussing helical, so the standard lenses don't have one. The outer mount is for other lenses which have their own focussing device. Its difficult to measure. I have taken the locking pin for reference.

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

F 2.0.

F 8.

F 22.

Closest focus  is 78cm from outermost edge of the lens, F 8. Focus on the program wheel of the camera.

As expected, the performance of the Contax mount lens is similar to the M39 mount lens. Although this is an older lens which can be found for low prices, it's decent. Wide open has some more flare than the M39 version at F 2, stopped down it's sharp. The lens has no close focussing capablities. It is relatively small and lightweight, particularly for a F 2 lens. A nice lens which offers 1 usable stop more than standard.

The Contax rf mount adapter is difficult to find and sometimes expensive, but Contax mount lenses are often much cheaper than their M39 versions. This one was very cheap and I already had the adapter. Otherwise there is no real advantage in comparison to the M39 model which weighs less for the combination adapter/lens.