Transferring a Mamiya TLR lens to another shutter

I recently undusted my trusty Mamiya C330 and am mesmerised once again. Composing with a ground glass really is something else. Now, when I got this camera and a bunch of lenses several years ago, I must have never paid much attention to the 55/4.5 lens, because as it turns out, the shutter is completely off: its blades were sticky initially and now close in slow motion (and rarely close all the way). What's more, the f/4.5 aperture setting looks more like f/8 to my eyes (even at its widest setting the blades don't move out of the way). If I had to guess, I would say someone took this apart and wasn't very successful in putting it back together in the right order.

No problem I thought, since I have a Sekor 105mm DS f/3.5 lens lying around that is of no use to me with its broken rear lens elements (I didn't do it, I swear!), so I'll just transfer the glass of the 55mm lens to the shutter of the 105mm lens. As it turns out, I'll also have to swap the aperture rings and re-solder the flash cable (the 2 lenses have different connectors). When it comes to shutters, my experience is close to zero, but I should be able to do that!

However, one issue I have not been able to solve is that the 55mm lens (the one on the left in the attached photo) has 6 aperture stops whereas the 105mm lens has 8. I have looked at the service manual, but am struggling to locate the part where the shutter clicks are defined. Can someone shed light on this for me?

Also, does the bent metal strip at the front of the photo look familiar to anyone? It was stuck between the 55mm lens and its lens board. I don't see it in the exploded views in the service manual.

Thanks!
Alex

Hmm. It's hard to be sure. Not the best possible photo. But the two shutters' front threads seem to have different inner diameters. If so, swapping cells is impossible and y'r question about aperture scales is moot.

I think both use a #0 shutter so the cells should be interchangeable.

That metal strip goes under the shroud around the viewing lens. Right side (from the front) where the shroud is raised. One of the 4 screws attached from the rear should go through the hole. Not sure what it achieves. Maybe grounding?

Instead of swapping the aperture ring, you can note where the lens is wide-open (the blades just get out of view when looking at the pupil), that's the 4.5 reference. Then transfer the marks from the other shutter on a piece of paper and stick it in. Should work since the scale is linear.

I think the extra strip of metal does ground the shutter to the body, I don't think any of the TLRs had a hot shoe (?), but the ground connection of the shutter should be connected to the body's cold shoe, and the black painted surfaces aren't conductive.

Keep in mind that the same size shutter is used on all the lenses, but they have very different pupils (internal aperture sizes). So slow, wide angle lenses typically do not need to have the aperture open as far as it physically can. Your shutter's aperture might be fine and it just needs to have the shutter mechanism cleaned.

The aperture scales of the two shutters will not be the same, that is f/5.6 on the 105 shutter will not be the same physical opening as f/5.6 on the 55 shutter. You'll need to compare the physical openings to understand how to transfer the scale. Also watch out for any thin shims used to adjust the spacing of the lens groups or to match focus between the taking and viewing lenses.

Thanks everyone! And apologies for the delay. Life has been keeping me busy.

reddesert said:

Your shutter's aperture might be fine and it just needs to have the shutter mechanism cleaned.

Click to expand...

I'd be happy to try that, if someone could point me in the right direction with this. Quite a few Youtube videos deal with these shutters, but none of the ones I've seen go as far as the aperture blades. Sadly, I am quite convinced that any attempt to do this on my own would render the shutter completely unusable (not that that's too different from its current state).

I haven't re-soldered the flash cable yet, but I've been able to figure out how to transfer the shutter stops and clicks between these 2 shutters: The shutter clicks are provided by the aperture scale ring (the very first part when looking at the lens front) in tandem with a tiny little metal ball (next to the red aperture index marking in the second photo; next time I take one of these apart I will put the shutter on a tray, just to be safe). Swapping these 2 is all that's needed to get the aperture to open the right amount for each aperture.
However, we still need to tell that ring how far it should be able to turn. And that's achieved by (a) swapping the 2 rings that sit directly underneath the aperture scale rings (on the left side in the second photo). They appear to be identical, but on closer inspection I noticed that their notches are a little different. And (b) moving the raised screw that can be seen next to the metal ball in the second photo (the 55 mm lens has a raised screw, the 105 mm lens doesn't). Now the aperture ring only moves within the range that's imprinted on it. reddesert was indeed right about the pupil opening (the iris on the 55 mm lens only ever opens half-way).

diluted dilated said:

Thanks everyone! And apologies for the delay. Life has been keeping me busy.



I'd be happy to try that, if someone could point me in the right direction with this. Quite a few Youtube videos deal with these shutters, but none of the ones I've seen go as far as the aperture blades. Sadly, I am quite convinced that any attempt to do this on my own would render the shutter completely unusable (not that that's too different from its current state).

Click to expand...

I think you've established that there's nothing wrong with the aperture. It's just the shutter that is sticky. The shutter and aperture mechanisms are separate.

Personally, my barbaric low-impact method of cleaning a clockwork leaf shutter, if it's not something incredibly valuable, is to: remove the front plate; drip or spray a little bit of electronic contact cleaner (the kind that evaporates quickly and leaves no residue - common brands are CRC and Deoxit) into the mechanism; put the front plate back and exercise the shutter several times. This will often revive a slow-speed mechanism that is draggy due to a tiny amount of residual oil or dirt, but it is less likely to solve your problem of a shutter that is sticky enough that the leaves don't close.