OCT-18 lens to Canon EOS (EF) camera adapter for zooms

This adapter can be used to install some LOMO (Lenkinap, KMZ) lenses with OCT-18 mount (for turret Konvas) onto cameras with EF mount (Canon EOS). It allows infinity focus if you lens can physically fit it (read details below).

This is simple adapter - it holds mount of the lens so it can't rotate. This means that it fits zoom lenses perfectly (Foton, Lenar, OPF series).

But most of OCT-18 primes needs to rotate in the mount in order to focus properly. You still can focus them even using such simple adapter, but behavior of the lens will change in this case - focus ring will become immovable, and you'll have to turn optical block for focusing that is not convenient.

One more issue is short length of the adapter necessary to provide infinity focus. This leads to interaction between camera interior and stoppers in the rear part of the OCT-18 lens mount. It is better to take these two screws out of the lens and save them till you decide to install it back on Konvas.

Third issue is that Konvas OCT-18 lenses have different design and different optical blocks. Some blocks have long back focal distance (BFD), others - short. Lenses with long BFD have rear optical element that doesn't protrude beyond of the mount toward camera interior. Such lens can be used.

But short BFD blocks need to be placed closer to film/sensor plane, so they protrude into the camera, and don't clear mirror and/or inner camera elements. So, make sure that your lens has long BFD block. Simple test is just to remove original canon lens and place your OCT-18 lens holding it in hands. If you can reach infinity focus - it is OK. If your lens doesn't reach infinity in such handheld test, it will NOT work with the adapter as well.