Mamiya Shift L 75mm f/4.5 for RB67: Shutter Not Operating
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This is a report on the repair of a fairly uncommon lens: Mamiya Shift L 75mm f/4.5 S/L to fit Mamiya RB67.
Lens was recently purchased and I believe the problem (shutter not operating) was caused in shipping.
Due to the large size of the lens and the front element (110mm) I had to use some tools that I often don’t need for most lenses. The front light baffle required my largest rubber removing tool and holding on the front housing was a retaining ring that not only was glued in place, but even after softening the glue it was on extremely tight. Using an adjustable spanner would not be a good option due to the fact that the ring was deep into the lens and a spanner would flex if the legs are long. Photo two shows the Mamiya spanner that was made for these sorts of situations- it is very heavy duty and will not flex.
Photo three shows the lens element group that needed to be removed before the front housing can be taken off. Interesting that Mamiya used a shim as shown as most RB lenses do not have shims on the front element groups.
The problem turned out to be a missing spring, probably came off during shipping. If you look at photo four, the small brass post at around six o’clock to the right of the speed escapement is missing the spring. While I could just install a new spring, the old one needed to be located so that I did not surface at some point and cause a problem in the field. After further disassembly, I located the spring and re-installed it. All is now working well.
One more interesting thing: looking at photo four you can see a small brass lever at around eleven o’clock. This is the X/M setting lever and this particular lens does not have an option for X/M flash sync, only X. But Mamiya used the same shutter that you put into the late model RB lenses so this switch is buried in the lens, not usable but technically the lens could be switch to M sync when it is taken apart.
This particular example was made in 1991 and they were available from Mamiya dealers for around $3000 in the mid 1990s. Or, Mamiya offered a lease through a third party of $106 a month for professional photographers.
