The Weltaflex is a TLR made by Welta in what was then East-Germany.
It has a 75/3.5 Ludwig Meritar set in a Prontor SVS shutter with speeds up to 1/300s. Variations with Meyer Trioplan 75/3,5 or Rectan 75/3.5 lenses set in a Vebur shutter (1-1.250s) are known.
There seem to be two versions. An "older" version with a red slide window for advancing or a "newer" model with a VEBUR shutter that has auto framing. This newer model does not have the rear red window for advancement but a pin and lever at the bottom of the camera. When the door is open, the numbering window by the shutter reverts to 0. I have not found the manual for this model but a lever at the bottom must be swung around to "lock" auto framing and numbering when the door is closed. Align the arrows on the film to bottom roller, then close the back and wind until it stops. You then need to fire the shutter to advance the film. If the lever is not used (swung back) you can fire the shutter at any time with the back closed, but the framing stops will not work. The button above the shutter lever is for locking the shutter, dot down to fire.
- Weltaflex at ukcamera.com
- Weltaflex instruction manual for both versions (red window / auto numbering) at Orphancameras website. The HTLM page can be translated using translate.google.com