Strange light leak in Contax 645 vacuum insert

[TerencePatrick]

Contax 645 using MFB-1B vacuum insert, Fuji 160S.

So I have these weird zigzag streaks going through the full length of a roll. I have one film back with one 220 vacuum insert along with 5 standard 120/220 inserts. Only the vacuum insert gives the streaks, none of the others exhibit this problem. Anyone ever see something similar and know of a solution? Are there seals/gaskets on the insert itself that require maintenance?

Thanks for any help you all can provide.

 

[Dirb9]

Has the film been through an x-ray machine? That looks like almost perfect sine waves from x-rayed film. The only other thing I could think of is that somehow when the film is wound, something is moving in and out of the path of the light leak.

 

[MikeSeb]

They almost look like some kind of interference pattern. DOesn't that 220 vacuum holder have slits that create the vacuum as the film moves over them?

Have you tried that insert in a different film back? It may be the back itself leaking light and interacting with the slits in the vacuum holder.

Just a thought....

 

[WRSchmalfuss]

Leak on the Contax 645 vaccum film insert?

Normally, that cannot happen! Why don't you shoot another film to find out. I bet you, it's not the vaccum insert.

Cheers

 

[TerencePatrick]

Dirb9, I was curious about the pattern as well. I don't think the film has been through X-Ray.

MikeSeb, it was my first and only roll I've processed using the vacuum back, so I'll have to run a test roll through before I use it on a job again.

 

[Q.G.]

It was just one roll?
Then do indeed run another one through the thing before thinking it was the back!

I'd also say X-ray damage.