Just acquired a Beirette K100. Lens was foggy so I took it apart, and found some rather interesting engineering. Foggy lenses seem to be a common problem on these cameras, and now I know why. The lens is a two element achromat design - but it is uncemented, and there is a thin paper washer between the elements to keep an airspace between them. I didn't know this, so when I started cleaning the glass, I was surprised to see liquid getting sucked into the lens... I had to gently break the lens apart, since the retaining ring is glued in. The upside is, I got to clean the inner surfaces that I hadn't even known existed. So the uncleanable haze these lenses tend to have, is hidden in the air space between the elements, that most achromatic lenses do not have. I suppose it saved the East Germans a penny or two on glue.
The other thing I saw was really quite clever. The shutter has three settings. Sunny, Cloudy, and B. The sunny setting is the "fast" shutter speed (looks to be about 1/60th), while the cloudy setting is not a "slow" speed - but rather an automatic double exposure. If you're familiar with how the common rotary shutter in a box camera works, this is much the same. On the sunny setting, the slot on the rotating sector passes over the aperture, exposing the film. The sector then stops in its travel when it hits a small pin that is set in place with the shutter speed dial. When you select the cloudy setting, the pin is moved out of the way, and the sector moves further, allowing a second slot in the sector to pass over the aperture, giving a second exposure of about 1/60th (and with about the same increment of time between each exposure). So effectively you get 1/30 on the cloudy section, but it's two exposures of 1/60th. This is such a stupidly simple way of giving more exposure times, that I'm actually surprised I haven't seen it on any actual box cameras before.
