David,

thank you for your reply.

that sticks up above the film plane where the third frame would fall: even
if it didn't scratch the film, it would probably buckle it enough to make it
impossible to get the film anywhere near flat), but the (expensive) glass
holder looks like it would be fine.
There is two glass holders for 9000ED, rotating and non-rotating.
I hope, you're talking about (less expensive) non-rotating...

Is there any problems with Newton rings and glass holders ?

--
Alex Tutubalin