RZ67 Pro II: Rough Focus from Broken Fine Focus Gear
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
Complaint on this Mamiya RZII was rough focus. In almost all cases, this is caused by a damaged fine focus gear.
On removing the right side cover, the mechanism is visible and the black plastic fine focus gear is visible. It looks OK from here. But in the video you can see that the lower half of the gear is quite damaged and makes no contact with the main focus gear. And, the small bits of the gear have broken off and get caught in the meshing metal gear. After removing the broken gear, I need to pick out the stuck broken bits with a pick as shown in photo two.
While I can put a plastic gear back on, I do have brass ones that will last the life of the camera. Toward the end of the RZ production, Mamiya seemed to have seen the error of their ways and made the gear from brass.
While the side cover is off, the second video shows me turning the mechanism and you can see all the parts that have to turn when you wind the cocking lever. I think that the drive shaft heading upward to the bevel gear that winds the film puts a lot of strain on the winding mechanism and this might be why we see a lot of failure in these parts. Also, this is just the right side, this same movement has to cock the mirror on the left side and also on the bottom of the camera it runs energy out to the shutter cocking mechanism. It is a lot to ask of these parts.
