Mamiya 6 vs Mamiya 7: Light Meter Photocell Location
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
Recently a question came up about the meter systems on the Mamiya 7/7II versus the Mamiya 6. Since I am servicing one of each today, this might be a good time to elaborate.
The metering systems are quite different in terms of where the photocell is located.
In the Mamiya 6, the photocell (SPD) is located on the side of the rangefinder assembly (shown in photo two). So, it reads light traveling through the large rangefinder window (viewfinder) and also the small rangefinder window. Photo three has a diagram from the Mamiya 6 service manual showing the area of the
SPD reading and it is roughly the size of the 150mm lens frame lines. If you don’t have a 150mm lens installed, you can figure that the sensitivity of the SPD is greatest at approximately twice the size of the rangefinder patch. There seems to be a bit of confusion on this point and I get many complaints of inaccurate meter readings with the Mamiya 6.
In the Mamiya 7/7II, the SPD does not read light traveling through the rangefinder. It is located on a small support peering out through the small rangefinder window as show in photo four (upper left of the glass window). Photo five shows the SPD location in a partially disassembled Mamiya 7 body, attached to a support with a small collector lens in front. Some rough testing shows it has about a thirty degree angle of light acceptance.
