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.
oftheherd
Veteran
Interesting. Thanks for the photos and commentary. I never took the bottom off any of mine and can only assume I had the spring you show. When I get access to them again I will have to look. Mine seemed to work alright with the two springs on the eccentrics, and would not work without them. If there was another spring under the base plate, as I said, I didn't know of it.
Some of the models had a flash contact, in fact, one is visible on the lens assembly. One has to be plugged in behind the lens assembly.
I also did a much less informative write up on the Mamiya Six, which I think is a nice, if slightly heavy, 6x6 or 645, if you have that model. I don't remember where I posted that except it is buried somewhere in one of the threads specific to the Mamiya Six.
It looks like you have done a good job of cleaning up that camera and understanding how it works. Good job. I think your friend will be really happy.
Some of the models had a flash contact, in fact, one is visible on the lens assembly. One has to be plugged in behind the lens assembly.
I also did a much less informative write up on the Mamiya Six, which I think is a nice, if slightly heavy, 6x6 or 645, if you have that model. I don't remember where I posted that except it is buried somewhere in one of the threads specific to the Mamiya Six.
It looks like you have done a good job of cleaning up that camera and understanding how it works. Good job. I think your friend will be really happy.
The beam splitter was cleaned on its (non-silvered) external surface but still looked pretty grotty inside. Mamiya, bless their hearts chose to glue all the optics in situ. So I had to carefully tease the mirror off its seat in the RF housing. I prudently opted not to touch the coated surface for fear of removing its reflective coating. I simply sprayed it a few times with Rosco lens cleaner, put it face down on some tissue to soak up remaining cleaner before flipping it over without wiping or touching the delicate coated surface. The beam splitter showed some signs of less than careful cleaning by a previous person at some point in its life. But the Mamiya finder eyepiece is not particularly large and the vital central area needed for the its RF patch remains intact, hence, the patch is still contrasty and very usable—so I deemed it fit for further service. Otherwise I would have had to cut to size a replacement from the beam splitter glass I keep on hand for the purpose.
Removing the beam splitter also enabled me to access the inner surface of the rear lens (immediately ahead of the external eyepiece glass).
If you've not done a rangefinder strip and re-assembly before, it's essential to note the precise orientation of various optical or other components. Since it is the beam splitter which creates the reflection within the finder received from the 45° mirror behind the RF window, its parallelism to the finder lenses is critical to the vertical calibration of the patch. Re-set it at a slight angle and the patch won't merge correctly.
The Mamiya design is at least more forgiving than say an M3 for instance. The M3 of course has a beam splitter integrated into its bonded prism assembly. But the front viewfinder lens must be carefully removed to reach otherwise inaccessible optical surfaces if they require cleaning, and that lens must be re-fitted in a precise orientation that's not easily fixed by reference to the adjacent surfaces of the housing. On the other hand, the Mamiya beam splitter simply had to be carefully seated against its perch on the RF unit, to restore accurate vertical patch alignment.
Here it is, re-attached to the rangefinder unit with a little clear epoxy on two sides to ensure it remains in place for many years. Vertical RF patch calibration was as new, a good result (or so I thought).
After refitting the rangefinder and attaching the top cover I noticed the previously-perfect vertical calibration was off by a mile. Off came the top cover again. The reason was immediately obvious. Mamiya had originally locked the round sub-assembly for the 45° RF mirror in position with a dab of paint or epoxy (it had faded, hard to say which). Apparently this was no longer doing its job, and in the course of removing the RF assembly, inspecting it, and working on it, the sub-housing had rotated in its threads.
Obviously, changing the angular position of the mirror relative to the finder alters the path of the light reflected by the beam splitter. At the risk of stating the obvious, it is, of course, how Mamiya originally calibrated the RF patch vertical alignment, when new. If your Mamiya Six has a patch that is out of alignment vertically, you'll need to adjust the threaded relationship between the angle mirror sub-assembly and the rest of the rangefinder. After removing, (12.5 full turns) inspecting and cleaning the now-accessible internal optical surfaces, I patiently aimed the patch at a contrasty black and white target and finessed the thread position of the mirror housing until the patch was merging correctly again, and fixed it securely in that setting with a spot of epoxy.
Here's the angle mirror sub-housing just removed from its threaded attachment to the RF assembly. The circular opening visible contains the 45° angled mirror. Naturally, when properly installed and aligned this opening will face the front of the camera—it's seen here about 90° out of its normal orientation.
With the rangefinder (finally) cleaned and correctly adjusted for its vertical alignment the remaining tasks are to check lens focus and calibrate RF to match, and install new light sealing in the back. Preliminary inspection of the film plane focus suggests it needs correction too. No conventional adjustment is provided for the lens infinity stop incorporated into the focusing dial. But removing the shutter revealed four shims at the rear mounting flange.
Each shim is a different colour, coded to thickness. When manufactured infinity focus would have been set by the selection of various combinations of shims as needed. It works, but can be tedious to re-set, if a particular camera subsequently needs correction, as this one appears to (perhaps not surprisingly given the state of its focus system on arrival).
That's it for tonight.
Removing the beam splitter also enabled me to access the inner surface of the rear lens (immediately ahead of the external eyepiece glass).
If you've not done a rangefinder strip and re-assembly before, it's essential to note the precise orientation of various optical or other components. Since it is the beam splitter which creates the reflection within the finder received from the 45° mirror behind the RF window, its parallelism to the finder lenses is critical to the vertical calibration of the patch. Re-set it at a slight angle and the patch won't merge correctly.
The Mamiya design is at least more forgiving than say an M3 for instance. The M3 of course has a beam splitter integrated into its bonded prism assembly. But the front viewfinder lens must be carefully removed to reach otherwise inaccessible optical surfaces if they require cleaning, and that lens must be re-fitted in a precise orientation that's not easily fixed by reference to the adjacent surfaces of the housing. On the other hand, the Mamiya beam splitter simply had to be carefully seated against its perch on the RF unit, to restore accurate vertical patch alignment.
Here it is, re-attached to the rangefinder unit with a little clear epoxy on two sides to ensure it remains in place for many years. Vertical RF patch calibration was as new, a good result (or so I thought).
After refitting the rangefinder and attaching the top cover I noticed the previously-perfect vertical calibration was off by a mile. Off came the top cover again. The reason was immediately obvious. Mamiya had originally locked the round sub-assembly for the 45° RF mirror in position with a dab of paint or epoxy (it had faded, hard to say which). Apparently this was no longer doing its job, and in the course of removing the RF assembly, inspecting it, and working on it, the sub-housing had rotated in its threads.
Obviously, changing the angular position of the mirror relative to the finder alters the path of the light reflected by the beam splitter. At the risk of stating the obvious, it is, of course, how Mamiya originally calibrated the RF patch vertical alignment, when new. If your Mamiya Six has a patch that is out of alignment vertically, you'll need to adjust the threaded relationship between the angle mirror sub-assembly and the rest of the rangefinder. After removing, (12.5 full turns) inspecting and cleaning the now-accessible internal optical surfaces, I patiently aimed the patch at a contrasty black and white target and finessed the thread position of the mirror housing until the patch was merging correctly again, and fixed it securely in that setting with a spot of epoxy.
Here's the angle mirror sub-housing just removed from its threaded attachment to the RF assembly. The circular opening visible contains the 45° angled mirror. Naturally, when properly installed and aligned this opening will face the front of the camera—it's seen here about 90° out of its normal orientation.
With the rangefinder (finally) cleaned and correctly adjusted for its vertical alignment the remaining tasks are to check lens focus and calibrate RF to match, and install new light sealing in the back. Preliminary inspection of the film plane focus suggests it needs correction too. No conventional adjustment is provided for the lens infinity stop incorporated into the focusing dial. But removing the shutter revealed four shims at the rear mounting flange.
Each shim is a different colour, coded to thickness. When manufactured infinity focus would have been set by the selection of various combinations of shims as needed. It works, but can be tedious to re-set, if a particular camera subsequently needs correction, as this one appears to (perhaps not surprisingly given the state of its focus system on arrival).
That's it for tonight.
Glad you found it interesting—I did, in fact, previously do a search and found your earlier posts you mentioned, and they were quite informative—thank you!