Sorting this one out for a friend. It arrived with stuck focus system and filthy optics. I believe it is a dual format version V with an Olympus Zuiko 75mm f/3.5 lens.
The Six features a fixed lens and focusing is achieved by moving the film rails. This is achieved by pushing the rails back from the lens using a system of four brass eccentric cams on the ends of two shafts, gear coupled. Spring pressure pulls the rails back toward infinity when the focusing wheel is rotated accordingly.
When in good order it works effectively enough but is a bit under-built to my eye. I'd be happy to see a more substantial film rail plate than the simply pressed and relatively-easily distorted sheet metal item Mamiya provided. The cams and their gear drive look good enough.
A few photos.
The underneath of the film rails. The two return springs and their lugs attached to the rails. The springs are fit to re-use. But the spring ends actually sit between the grooved flanges of the four eccentrics. Ie the eccentrics have to glide across the spring ends. That corrosion won't do anything for the feel of the focus wheel.
After five minutes of gentle cleaning with some Autosol metal polish the springs have a sheen again. Perhaps they'll run across the eccentrics better now.
The focus wheel is fitted to the end of the take up side eccentric shaft. Turning the wheel actuates the two eccentrics directly. But how to move the take up side of the film rails with it? The solution is a small gear train, sprung to eliminate gear backlash (clever) and ensure even, synchronised movement of the rails at all corners. After removing the lower cover these components are visible. Not much to do here, it's all OK. A speck of oil on the intermediate gear bearing surfaces, cleaning off any loose dust and the cover can go back on. Note the fine cut gear teeth. Not much backlash in those to begin with. But the tension spring prevents even that from manifesting.
And here are the two focus shafts and their eccentrics, visible with the rails removed. Note the grooves in the eccentrics. The two spring clips, in situ, are trapped by the centre lug under the rails, on the one hand, and the grooves in the eccentrics that retain their ends in situ. Being brass, the eccentrics had no corrosion but a very gentle dressing with Autosol helped remove old lubricants from the grooves and return a shine, ready for a dab of moly grease and re-assembly.
First the springs have to be guided under the shafts. The rails are then re-fitted. Using something like a dental hook the springs are then teased up and over the lugs to return the rails towards the lens (infinity) when the focus wheel is rotated thus. Watch that all the spring ends are sitting correctly inside the eccentric grooves. If you did it right it should work like this (video).
Next job is to clean the optics. After removing the cover (two screws each end and the wind knob must be removed on this model) the rangefinder and focus wheel is visible.
And here is the rangefinder:
That's it for tonight.
The Six features a fixed lens and focusing is achieved by moving the film rails. This is achieved by pushing the rails back from the lens using a system of four brass eccentric cams on the ends of two shafts, gear coupled. Spring pressure pulls the rails back toward infinity when the focusing wheel is rotated accordingly.
When in good order it works effectively enough but is a bit under-built to my eye. I'd be happy to see a more substantial film rail plate than the simply pressed and relatively-easily distorted sheet metal item Mamiya provided. The cams and their gear drive look good enough.
A few photos.
The underneath of the film rails. The two return springs and their lugs attached to the rails. The springs are fit to re-use. But the spring ends actually sit between the grooved flanges of the four eccentrics. Ie the eccentrics have to glide across the spring ends. That corrosion won't do anything for the feel of the focus wheel.
After five minutes of gentle cleaning with some Autosol metal polish the springs have a sheen again. Perhaps they'll run across the eccentrics better now.
The focus wheel is fitted to the end of the take up side eccentric shaft. Turning the wheel actuates the two eccentrics directly. But how to move the take up side of the film rails with it? The solution is a small gear train, sprung to eliminate gear backlash (clever) and ensure even, synchronised movement of the rails at all corners. After removing the lower cover these components are visible. Not much to do here, it's all OK. A speck of oil on the intermediate gear bearing surfaces, cleaning off any loose dust and the cover can go back on. Note the fine cut gear teeth. Not much backlash in those to begin with. But the tension spring prevents even that from manifesting.
And here are the two focus shafts and their eccentrics, visible with the rails removed. Note the grooves in the eccentrics. The two spring clips, in situ, are trapped by the centre lug under the rails, on the one hand, and the grooves in the eccentrics that retain their ends in situ. Being brass, the eccentrics had no corrosion but a very gentle dressing with Autosol helped remove old lubricants from the grooves and return a shine, ready for a dab of moly grease and re-assembly.
First the springs have to be guided under the shafts. The rails are then re-fitted. Using something like a dental hook the springs are then teased up and over the lugs to return the rails towards the lens (infinity) when the focus wheel is rotated thus. Watch that all the spring ends are sitting correctly inside the eccentric grooves. If you did it right it should work like this (video).
Next job is to clean the optics. After removing the cover (two screws each end and the wind knob must be removed on this model) the rangefinder and focus wheel is visible.
And here is the rangefinder:
That's it for tonight.
