Obscured corner of negative

I have a Rolleidoscop, 6x13 stereo camera and the left hand negative of each stereo pair always has the bottom righthand corner slightly obscured. I have checked carefully the rear opening and inside the camera-back to see if anything is protuding and cannot find anything. The lenses are clean and the apertures working correctly, also the shutter. Any thoughts on what could be causing it? See attached photos.

The mirrored corner of the other image is also light-blocked. There's some light blockage precisely between the two lenses near the front of the camera shadowing exposure of both stereo frames. Perhaps this is a common issue with this camera... a baffle design/construction flaw? Or perhaps the manufacturer misjudged lens coverage and they're not quite centered?

Old-N-Feeble said:

The mirrored corner of the other image is also light-blocked. There's some light blockage precisely between the two lenses near the front of the camera shadowing exposure of both stereo frames. Perhaps this is a common issue with this camera... a baffle design/construction flaw? Or perhaps the manufacturer misjudged lens coverage and they're not quite centered?

Click to expand...

Or there is something vignetting both lenses in front of the lenses, like a filter.

Old-N-Feeble said:

The mirrored corner of the other image is also light-blocked. There's some light blockage precisely between the two lenses near the front of the camera shadowing exposure of both stereo frames. Perhaps this is a common issue with this camera... a baffle design/construction flaw? Or perhaps the manufacturer misjudged lens coverage and they're not quite centered?

Click to expand...

It looks like the other is light blocked, but not so, all the other negative pairs only have the left one with the corner obscured. I don’t think it is a design flaw, Rollei were very meticulous i think (though i may be wrong)....thank you.

Sirius Glass said:

Or there is something vignetting both lenses in front of the lenses, like a filter.

Click to expand...

There is no filter...

Actually Rollei was caught with their pants down a few times. Most notable iirc was a soft lens on the 2.8B and internal reflections in some early Automats. We love them though, warts and all.

How old is your Rolleidoscope? Apparently some of the earliest were converted from 117 to 120 film.