The Mamiya-Six folder is quite a rarity outside of Japan. First introduced in 1940 with 14 models spanning 18 years of production, these Japanese 6×6 folders use a novel film plane focus mechanism.
The film runs over a floating carrier plate and is held in place by a sprung sliding pressure plate. A thumbwheel on the rear of the camera operates both the rangefinder linkage and a series of cams which moves the film carrier plate in/out.
This design has two major advantages over traditional front cell focussing folders; 1) it offers better close focussing sharpness since the lens is in effect unit focussed, and 2) the pressure plate moves with the carrier plate keeping the film even and flatter as its traverses the carrier plate.
However, if the cams seize or wear, the springs loose tension or the pressure plate is lost then its junk. So its good idea to check that the mechanism operates freely and the plate is included.
This 1955 Mamiya-Six IVS was bought for £80 and was sold as being in excellent condition. Upon arrival it was evident that “excellent” has a different meaning in Japan.
The camera body had little corrosion, the shutter fired and the front elements looked clean, however the trim was peeling, the rear lens group was completely fogged with fungus and the view finder was hazy. The bellows were very dry, sagging and full of pin holes. The focus mechanism was a also little stiff but all parts were present.
I therefore contacted the seller and negotiated a sizeable discount.
Moving on, I first decided to strip the top plate and lens and clean all glass and mirrors. The view finder cleaned up well but the rear lens group was beyond redemption.
My initial thoughts were to graft a mint Yashinon 80mm lens onto the Mamiya-Six, but the lens to film plane distance required significant spacing and there was no guarantee that the focus cams would match lens focus.
Fortunately, the uncoated D-Zuiko 75mm f/3.5 was a Tessar clone and its rear lens group looked optically identical to a coated Carl Zeiss Tessar lens I had salvaged from an shabby 1955 Super Ikonta.
So I assembled the elements and set about collimation to check for compatibility. The lens collimated better than expected, edge sharpness looked good (at f/3.5) and there was no sign of astigmatism or colour fringing. I decided that this would have to do for now as the front element had quite a few polish marks and I really would need find a replacement.
It’ll be interesting to see how this mixed optics perform on film. The Zuiko is renowned for its dreamy OOF areas and the coated Tessar is known for its edginess.
I gave the camera a good clean, re-glued the trim, lubricated all moving parts and checked the shutter timing.
This Mamiya-Six IVS has a Seikosha-Rapid shutter (a Compur-Rapid inspired clone) capable of speeds up to 1/500s.
This one fires 2/3rds stop slow at all speeds….It’ll need a clean, but this will have to wait until I decide on what to do with the bellows.
The bellows have about a dozen or more pinholes, they sag and the leather looks pretty tired. The bellows on the other Mamiya-Six also have a few pinholes, so I might just bite the bullet and order some custom replacements for both.
The Mamiya-Six IVS differs from the K-II. It has one red window (for first frame position), a film counter and a double exposure prevention mechanism (that even pops up a little red flag in the viewfinder) but it lacks the K-II’s 6×4.5 mask flaps.
I ran a test roll through the camera to check film spacing and it varies between 61mm and 67mm, with spacing being tighter at the beginning of the roll.
All in all this Mamiya-Six IVS is a well made camera (albeit not quite in the Zeiss quality league) with it’s thumbwheel film plane focus, bright viewfinder and DEP, a fully restored user may well rival a Super Ikonta III. However, I believe the later K-II may prove to be an even better match.
Update to follow!