Rodenstock XR Heligon 68 mm f:1

This massive piece of glass is a lens used for X-ray Tv projection. One such lens connects to a X-ray machine cascading to a second lens which projects the image on a television camera. It has a fixed focus and lacks an aperture ring. It can be used for macro photography. The focus distance is about 30 cm and the back focus less than 1 cm. Sony NEX cameras are very well suited for this lens as you need to mount the lens close to the APS-C sensor. There is no vignetting with an 68 mm.



With an aperture for f/1 there is still an acceptable depth of field. There are some Rodenstock XR lenses with a record f/0.75 but focus then besomes very thin. The lens produces nice dreamy images and is therefore best for flower photography.







A few more:

Bell and Howell 51 mm f/1.2 projection lens

Projection lenses are good for experimentation. They are relatively cheap, can be very sharp and are easily available in wide apertures. This Bell and Howell is a gem! I still have not found a way to mount it on my Nex but just pressing it against a C-mount adaptor already gives some nice shots. Of course: no focusing or aperture control.

A cheap brand-less CCTV lens 25 mm f/1.2

This tiny little brand-less CCTV lens can be bought for a few dollars and features a very wide aperture of F/1.2. It mounts on the Sony Nex using a C-mount adapter. Aperture can be controlled by the blue plastic ring, the focus distance by the front metal ring. On the NEX C3 the focal length of 25 mm is not enough to cover the whole APS-C sensor. A full frame can be covered without vignetting from a focal length of 50 mm or more.



By placing a small screwable ring between the lens and adapter it becomes possible to focus at closer distances. The following two pictures are examples of cheap macro photography. The advantage of the ring is that a larger portion of the sensor is being covered.