I decided I should set to and load some sheet film holders, both 4x5" & 9x12cm DDS types and some older 9x12cm holders that fit my Zeh Zeca. Having a rummage through the camera cupboard, I came across these double sided plate holders, but these don't fit any camera I've got. They're a different outer dimension to the DDS holders which fit the MPP.
They seem to be of the 10x15 cm size and would be the type used in Zeiss Palmos or Zeiss/Contessa-Nettel cameras with focal plane shutters. Also could fit old ICA / Zeiss SLR cameras.
I have identical holders, the same dimensions, just grabbed one from the garage, and it has a plate in it (processed). It's a 9x12 plate holder, but yours has an adapter in the last photo, I guess for v8x12b film. I have no idea what camera they fit,
I have seen these also for 6,5 x 9 cm film (from a seller in Vienna). These are not from Zeiss, Ica, or Contessa-Nettel, but might fit camera's made by them.
Your holders came with a Mentor (klapp reflex) camera (see below) - aka Goltz & Breutmann reflex.
I have a comparable camera from Ica/Zeiss with almost the same type of holders, albeit from Zeiss.
Catalogue: https://www.pacificrimcamera.com/rl/03156/03156.pdf
However, my holder, which is identical to the OP's, is too wide, I just tried it. The Mentors use the same fit dark-slides as ICA. In the photo above the plate holder appears to be wider than the gg holder.
However, my holder, which is identical to the OP's, is too wide, I just tried it. The Mentors use the same fit dark-slides as ICA. In the photo above the plate holder appears to be wider than the gg holder.
Well, as I understand, the Mentor reflex is not the same as the (older?) Goltz & Breutmann klapp reflex, not sure though. I see different reflexes mentioned in the catalogue. Further, in the catalogue they distinguish different but almost identical plate sizes; your Mentor camera might be made for imperial size plates, and your plates are perhaps continental, or vice versa? (and the catalogue mentions that the double dark slides are aluminium bound)
Btw my Ica / Zeiss plate holder (739/6) for the ICA klap reflex has the same outer dimensions as the op's plate holder: 11 x 17 cm and are of the slide-in type; they are also aluminium bound (photo - and cam - not mine):
Thanks Ron and Ian. I think I got these with some other plate holders & film sheaths for my 9x12 Zeh Zeca, most ilkely from a camera fair when I was in NL back in the noughties. I "rediscovered" them when looking for something else. As you do!