Mamiya C330 Professional F - panel blocking film exposure

[Sirius Glass]

I think I would rather stick to one lens than waste all that film between frames, but maybe on occasion I could do that. Thanks for responding and the tips!

OR take it to a camera repair man who can reconnect the proper parts and then you can freely change lenses whenever you want.

 

[MattKing]

OR take it to a camera repair man who can reconnect the proper parts and then you can freely change lenses whenever you want.

Sadly, I'm not sure there is anyone left in our metro are of approximately 3 million people who work on cameras like this.

 

[MrBiswas]

Sadly, I'm not sure there is anyone left in our metro are of approximately 3 million people who work on cameras like this.

Beau Photo Supplies has someone that they send cameras to. He did some work on this one and CLA'd it, but it was quite expensive.

 

[MrBiswas]

I think something to consider is if the switch is loose or been forced/over rotated and simply needs resetting. Set the camera in 'Unlock' and pry off the thin aluminium cover (it's likely you'll damage it and was originally a replaced on a service), unscrew the switch knob and see if this allows the baffle to close, if not undo the two screws holding the dial on and undo but don't remove the connecting nut to the baffle linkage, does the baffle now close? If it does tighten it back up and reassemble.

View attachment 395902

This was a good idea, but unfortunately after loosening and retightening it didn't seem to make a difference. I think the issue must be internal. I'm debating on whether I want to go through the hassle of opening it up.

 

[reddesert]

I am not sure what the fault is. However, I think the baffle is riveted onto the rod, and I'm not sure there is an easy yet reversible way to remove the baffle. So, if this were my camera, I would not remove the baffle now. I'd kludge something - perhaps just an L-shaped piece of metal blackened and held onto the side of the chamber with foam sticky tape - that held the baffle down and out of the way. You would lose mid-roll interchanging lenses in daylight (could still change them in a dark-bag), but would expose the entire frame, and retain the option of one day fixing it to work properly.

 

[Sharktooth]

I had a look at my C33. It's an older model, but the baffle mechanism looks the same.

The pivot rod toggles between the upper an lower positions. By toggle, I mean that is rotated to one position or the other via a toggle spring mechanism (not visible). If the baffle is in the upper lock position, and you turn the knob slightly away from lock, it will snap back to the lock position. If you turn the knob more than half way to the unlock position, it will snap to the unlock position. It will go one way, or the other, and not stay in some intermediate position. That's what I mean by "toggling".

To check if the toggle mechanism is working, set the knob to the unlock position, and then turn it slightly away from the unlock position. Let go of the knob, and it should snap back to the unlock position. Do the same at the lock position. If the knob doesn't snap back, then the toggle mechanism is faulty.

If the mechanism seems to be toggling, then the next thing to check is the orientation of the flat on the pivot shaft. The baffle is connected to the pivot shaft via a flat spring steel strip. The spring steel strip is riveted to the baffle, and screwed to the flat on the pivot shaft. The baffle should be parallel to the flat on the pivot shaft. With the baffle in the down position (not blocking light), look at the orientation of the that flat. The flat should be tilted down slightly below horizontal. You should be able to see this clearly with a flashlight pointed under the flap. If that flat is tilted up, then the shaft hasn't rotated far enough, so there is some issue with the stop for the shaft (which can't be seen). If the flat is tilted below horizontal, then the baffle should also be tilted below horizontal, which it obviously isn't in your case, so this means the spring steel strip is bent, and you could probably bend it back into position.

The reason the baffle is attached by a spring steel strip is to ensure a good seal. The pivot shaft over-rotates in both the locked and unlocked positions. This means the flat on the shaft is more than 90 degrees in the up position, and below 0 degrees in the down position. The spring steel strip allows some compliance to clamp the seal, or to keep the baffle out of the image zone.

 

[campy51]

I really don't know much about this camera, but I am wondering if the shaft is twisted and the knob and flap are in different starting positions and maybe binding a little.

 

[MrBiswas]

I had a look at my C33. It's an older model, but the baffle mechanism looks the same.

The pivot rod toggles between the upper an lower positions. By toggle, I mean that is rotated to one position or the other via a toggle spring mechanism (not visible). If the baffle is in the upper lock position, and you turn the knob slightly away from lock, it will snap back to the lock position. If you turn the knob more than half way to the unlock position, it will snap to the unlock position. It will go one way, or the other, and not stay in some intermediate position. That's what I mean by "toggling".

To check if the toggle mechanism is working, set the knob to the unlock position, and then turn it slightly away from the unlock position. Let go of the knob, and it should snap back to the unlock position. Do the same at the lock position. If the knob doesn't snap back, then the toggle mechanism is faulty.

If the mechanism seems to be toggling, then the next thing to check is the orientation of the flat on the pivot shaft. The baffle is connected to the pivot shaft via a flat spring steel strip. The spring steel strip is riveted to the baffle, and screwed to the flat on the pivot shaft. The baffle should be parallel to the flat on the pivot shaft. With the baffle in the down position (not blocking light), look at the orientation of the that flat. The flat should be tilted down slightly below horizontal. You should be able to see this clearly with a flashlight pointed under the flap. If that flat is tilted up, then the shaft hasn't rotated far enough, so there is some issue with the stop for the shaft (which can't be seen). If the flat is tilted below horizontal, then the baffle should also be tilted below horizontal, which it obviously isn't in your case, so this means the spring steel strip is bent, and you could probably bend it back into position.

The reason the baffle is attached by a spring steel strip is to ensure a good seal. The pivot shaft over-rotates in both the locked and unlocked positions. This means the flat on the shaft is more than 90 degrees in the up position, and below 0 degrees in the down position. The spring steel strip allows some compliance to clamp the seal, or to keep the baffle out of the image zone.

The toggle action is operating normally. The pivot rod is not rotating far enough in the LOCK position to tilt the baffle below horizontal, which is causing the blockage of the film. I posted a video of the operation here: https://www.photrio.com/forum/threa...el-blocking-film-exposure.213034/post-2886861

 

[Sirius Glass]

Sadly, I'm not sure there is anyone left in our metro are of approximately 3 million people who work on cameras like this.

If one were to ignore the tariff war, hop on an airplane and come to visit me in Los Angeles and I will drive you to Samy's camera.

 

[Sharktooth]

The viewpoint in the video is too high, so you can't see the angle of the pivot shaft flat. If the spring steel strip that links the baffle to the pivot shaft is bent, then you'll see the the baffle in the wrong orientation, even if the pivot shaft has rotated fully.

If that steel strip is bent, then the baffle won't be fully down even if the pivot shaft is properly rotated. The baffle being in the wrong orientation doesn't necessarily mean the pivot shaft hasn't rotated fully. The only way to know if the pivot shaft is fully rotated is to actually check the orientation of the flat on the pivot shaft.

The wording of the description is important, since it's still not clear if you've actually looked at the rotation of the pivot shaft on its own.

 

[MrBiswas]

The viewpoint in the video is too high, so you can't see the angle of the pivot shaft flat. If the spring steel strip that links the baffle to the pivot shaft is bent, then you'll see the the baffle in the wrong orientation, even if the pivot shaft has rotated fully.

If that steel strip is bent, then the baffle won't be fully down even if the pivot shaft is properly rotated. The baffle being in the wrong orientation doesn't necessarily mean the pivot shaft hasn't rotated fully. The only way to know if the pivot shaft is fully rotated is to actually check the orientation of the flat on the pivot shaft.

The wording of the description is important, since it's still not clear if you've actually looked at the rotation of the pivot shaft on its own.

I did check the rotation of the pivot shaft on its own, sorry if that wasn't clear in the previous posts.

Regardless, I fixed the problem! There was a piece of broken glass that must have somehow come off the mirror at some point and got lodged under the mechanism that turns the pivot rod, preventing it from making its full range of motion. Took me a moment notice it, but the baffle is fully mobile now. Just have to glue the leather back on.

Thanks to everyone for their time, especially @grahamp and @MattKing.

 

[MattKing]

Good news!
Can you see the damage on the mirror itself????
That looks like it also could come from a focusing screen.

 

[MrBiswas]

Good news!
Can you see the damage on the mirror itself????
That looks like it also could come from a focusing screen.

No sign of damage anywhere on the mirror and the focusing screen is new. The piece is reflective on one side, so it's definitely the mirror. Maybe a remnant of an old repair.

 

[grahamp]

 

[campy51]

Piece of the mirror was my next recommendation.