The Zeiss Ikon Tengoflex is a little-seen twin-lens reflex box camera that surprises with its photo quality.
There isn't much written about the 6cm x 6cm Tengoflex, but I was able to learn that it apparently was made and traded to Sweden during World War II for raw materials.
For the most part, you'll find that most Tengoflexes still are in Sweden, although certainly the Internet has allowed them to be elsewhere -- like the one that I have, for example.
Like nearly all Box Tengors, it has an uncoated Goerz Frontar, an achromat. There is the ability to select one of two apertures and one of two focusing distances. This is accomplished like any other Box Tengor. Selecting the closer distance swings a lens into place behind the shutter assembly.
The shutter release is on the top of the camera, which makes it very simple to use. Pulling open the lid of the viewfinder reveals a brilliant finder with panels on each side to block light.
There are two available shutter speeds: Instant and T, although Instant isn't marked and T is really B. That's a bit comical, but that's how it is with the Tengoflex.
There isn't much complexity in using the Tengoflex. Frame your shot in the viewfinder and press the shutter release. The camera has double-exposure prevention, so you should then wind on to the next frame. There is a small red window with a sliding cover for proper alignment of the frame number. Depending on the film being used, the number printed on the film's paper backing might be very visible or nearly impossible to see.
I have had a lot of fun with this camera, and I think that you'll find the lens is much better than you expected. It's one of my favorite box cameras and without a doubt one that you hardly ever see out in public today.