Mamiya 7: Testing Aperture Priority Auto Exposure
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
One of the battery of tests that are done on the Mamiya 7/7II on intake is check of the light meter automatic setting. On the Mamiya 7/7II this is an aperture priority system.
The equipment that I use for this test is a Kyoritsu LB-360 light box coupled with a Kyoritsu CEE-1A Analog EE tester.
Operation is straightforward: Matching ISO is set on the camera and the tester. Camera is set to “A” and a random f stop is set on the lens. The sensor is installed in the aperture of the camera body and the shutter is released. The meter on the tester will go to the zero setting if the exposure is correct, otherwise the meter will show the amount of error. In this case, error indicated is + 0.1 f stop which is well within specs.
While high quality cameras can have specifications of plus or minus 0.3 f/ stop, mass produced point and shoot cameras may have an acceptable error of up to 0.5 f/stop when set on automatic.
