I have a few hints, notably the style of writing on the front (the 'Praktiflex'), the shape of the speed selector (smooth with 3 ridges), the speeds on the selector (red 'B'; 25; 50; 75; 100; 200; 300; 500); the size of the frame advance knob (27.5mm); the presence of strap lugs; the lack of a hand-scribed 'Germany' on the back (instead, under pop-up hood: KW logo, and "KAMERA-WERKSTATTEN NIEDERSEDLITZ-DRESDEN"); the 'R' over the rewind lever (don't know if it was originally black; the camera had extensive paint loss). From what I've found on the 'net, that would date the camera to roughly 1940-41 (?????). Serial no. is 27xxx. Lens is the M40x1 Victar Anastigmat 5cm f2.8 of course. I have not seen an identical camera anywhere on the 'net, the closest I've seen is here (difference: no KW logo and writing under the pop-up hood): http://www.praktica-collector.de/078_Praktiflex_11th.htm I haven't tried any film yet, I still have to find a replacement mirror as it is more than 50% de-silvered. I have already cleaned it and replaced what was left of the original rubberized fabric with kid leather. Everything works as it should, the only major fault was a missing adjustment screw for the plane of the focusing screen, causing it to focus incorrectly on one side of the frame. Shutter curtain looks good, still not 100% sure there are no remaining pinholes after treatment. And of course the 'instant-return mirror' operates correctly P). BTW, this is not my oldest camera with an instant-return mirror; both my 1932 KW Pilot (original, fixed lens) and my (1920s?) Thornton-Pickard Bijou Reflex (4.5x6 plate) SLRs have functionally similar mirror lift and spring-assisted return mechanisms. The T-P has the added feature that the mirror will only return if the top focusing hood is retracted; it's a 'self-capping' shutter so the mirror is not needed to block the light from the film or plate as the shutter is cocked. That wasn't an issue with the behind-the-lens shutter of the Pilot, so of course the mirror on that is more like a modern SLR.