Where are these light leaks coming from?

[MCB18]

Did some testing on my 70mm back with a roll of 120 film, and got some odd results… testing the back with a very bright flashlight in the lens hole of the camera (in my darkroom) I can see no light leak, but when I took some images I got very odd horizontal lines between the exposures. I am unsure where these could come from, so I’d definitely appreciate any advice or help! The back in question is an RH50 70mm back attached to the RB67 with a 3-D printed adapter.

 

[boring old man]

The "leak" looks like part of the image, and you should have border at the bottom of the image. Could the adaptor be upside down?

 

[AnselMortensen]

Note the soft edge of the image, a space, and then the "light leak".
I think that there is something possibly infringing on the image area.

 

[MCB18]

The "leak" looks like part of the image

Note the soft edge of the image, a space, and then the "light leak".
I think that there is something possibly infringing on the image area.

No, it’s definitely not part of the image. The little bar is outside the film gate, I checked. I’m not entirely sure why that edge is soft on some exposures.

and you should have border at the bottom of the image

This is 120 film in a 70mm back, so one of the edges is cut off yes.

 

[koraks]

Looks like the film gets some exposure to the side of the frame where it curves backwards onto the roll, given the falloff. I suppose there's plenty of opportunity for this to happen int he 3D printed contraption shown. I'd start by trying to close up any seams on that thing.

 

[OAPOli]

I'm not familiar with this back, but you can get similar light leaks on Hasselblad and Bronica backs where you have rollers over the film. There is a small gap above the roller and if the light comes at steep angle (when stopped down a lot) you can get a small line of exposure between the frames.

 

[MCB18]

Looks like the film gets some exposure to the side of the frame where it curves backwards onto the roll, given the falloff. I suppose there's plenty of opportunity for this to happen int he 3D printed contraption shown. I'd start by trying to close up any seams on that thing.

The film doesn’t bend up right after the film gate, the rubber rollers in this back are massive as they use them to meter the film, so the film doesn’t start to bend until about an inch past the edge of the film gate:

I'm not familiar with this back, but you can get similar light leaks on Hasselblad and Bronica backs where you have rollers over the film. There is a small gap above the roller and if the light comes at steep angle (when stopped down a lot) you can get a small line of exposure between the frames.

I think that’s it… the dense areas line up bang on with the shiny rollers in the back.

Is there any way to fix this issue? Or is it just something that happens and not really anything to worry about?

 

[OAPOli]

Well since it is outside the picture area I wouldn't worry about it.

Out of curiosity, were those pictures taken stopped down?

 

[MCB18]

Well since it is outside the picture area I wouldn't worry about it.

Out of curiosity, were those pictures taken stopped down?

Around F/8 and f/11 mostly