Polaroid Full Frame Exposure - Mamiya RB67

[NYArtboy]

Hey all, I am working with a LB-77 Lane Polaroid Film back for my new (for me) RB67 and I have an issue. I am not able to expose the entire film area. Its exposing about a 3" square and leaving about 3/4" black bar on the right hand side of my horizontal frame. Is this normal? Am I doing something wrong? Do I need to work with a longer lens? Why wouldn't the exposed portion be in the middle then? :idea:

Here are the shot specs:

LB-77 Polaroid Back
Mamiya 90mm f3.8 C lens
Fuji 100 ASA B&W positive instant film

f 3.8
SS 1/2 (could it be the slow shutter speed?)

The exposed portion looks beautiful but a shame its not exposing the entire film.

Any thoughts?

[drg]

The modern Fuji film is a different size than the original Polaroid film in the exposable area. Different masks at one time were available and it may be that this is just clipping off the side of the film as it is a mask for say Spectra as opposed to another film.

The other issue, and I haven't used that back with that camera, is these backs can often be mounted in two different rotations. One is the right way and the other it will vignette the film. Also, if you have a square body, and the 6x7 was acheived in the front transport plate and that is missing, it is going to make a square image no matter what or always cut off part of the film.

Also, the film is essentialy square but the chemical transfer area is offset on the one side and if you put the film in backwards it expose over the chem pack and not the emulsion window.

See if you can
1. mount the film carrier differently
2. check for obstructions in the body
3. compare the Fuji Film to the older Polaroid (even exposed) to see where the image lies on the surface.

Hope this helps!!

[NYArtboy]

You're right Doc, completely missed that. :blush2: And unfortunately there is no other positions to mount the LB-77 film back. I am going to look into some other backs that may be able to position the polaroid more centered on the film. I used to like to keep my polaroids and test shots in the good ole days and the 'flush right' exposure of the LB-77 is not pleasing to me.

Thanks and if anyone knows of a polaroid back that will do centered 'vignetted' shots let me know!