Mamiya 6/7: Rangefinder Calibration of Lenses and Field Check
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
The question of rangefinder calibration comes up constantly with Mamiya 6/7 owners. Generally, a quick field test is to focus on something at infinity (a lamp pole 1/2 mile in the distance works well) and see if the image lines up when the lens is set on infinity. There is also an adjustment for meter and you can check that wilh a one meter ruler, but if infinity is good, in most cases one meter will also be in calibration.
Each lens on the Mamiya 6/7 system also has an adjustment for the cam but this rarely needs to be adjusted unless the lens had been disassembled at some point. I find that the 150mm lenses are often needing calibration.
The lenses should be calibrated separate from the body - they need to be adjusted independently so that they will work on any camera body.
The first photo shows the rangefinder adjustment fixtures that I use for the Mamiya 6/7 lenses. The second photo is of the two calibration standards. The one for the Mamiya 7 on the left and is fixed at infinity. The standard on the right is for the Mamiya 6 and is a new factory focus mount (a lens minus the glass and shutter). Both of these were supplied to a U.S. Mamiya service station by Mamiya Japan.
The video shows a Mamiya 6 150mm lens on the rangefinder fixture after being serviced. While it is adjusted at zero, the specs actually allow an error of -0.015mm.
