RB67 Revolving Backs: Four Versions and Common Issues
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
I am servicing Mamiya RB67 revolving backs today. Photo one shows all fours versions that are found in the wild these days:
1.) 1971 original style without double exposure prevention. Upper left
2.) 1981 Pro S style, double exposure prevention added and light seals on both side of the adapter. Upper right
3.) 1988 Pro S style 6x7/6x8. This is right before the Pro SD was introduced and required a replacement back plate of the body to use the full 6x8 format. Bottom left
4.) 1995 Pro SD style 6x7/6x8. Identical to the earlier Pro S style 6x7/6x8 type but no longer marked on the side with the formats. Bottom right
The dates that I have listed are on my copies shown here, production dates would extent on both sides of these dates.
While these adapters hold up well, there are a few issues that I usually see with them: broken pins (the wind actuator and double exposure prevention pins as shown in photo five);stiff rotation on most all of these and requires disassembly to separate the parts, clean and lightly relubricate); broken detent springs, shown in photo six; and of course light seals. If you are having a wind or back problem, the first thing I would check is the revolving back as it is the interface between the body and back.
These adapters will interchange with the two versions of the RB67 Pro S but the early Pro bodies will not not accept the later Pro S revolving adapteres due to the pin that controls the moving vanes when the adapter is rotated.
