An oxberry optical printer and rostrum stand often use very similar cameras infact there is very little difference between them.
An optical printer images the target upside down in the gate so you thread it in the projector the right way up. This helps you see what you are shooting. Its printed in the gate as if it were being projected so if you print to POSITIVE stock its ready for projection once it is processed.
However on a rostrum camera the artwork or the flat pegbar area infront of the operator is correct for your position but infact as a target its upside down if follow the system above for an optical printer. This means it gets imaged in the camera the right way up which will cause problems. Now, if you reverse the teeth (this is all for 16mm btw) on the camera sprocket and load the raw film in the normal take up magazine and run the camera backwards it will orientate the image onto the emulsion side at head of the film so the film can then be printed as above.
This can be seen in the crude image below where the little stick man on the bottom left is a person working at the peg bar artwork table.
Then, as in this video below, we load film from take up mag, reversed by sprockets and run in reverse (it runs forwards here just to load ref mark into place) we get an image orientated as it would be in a normal camera loading ready to be printed.
