Mamiya C TLR: Missed Frames from Oily Shutter Blades
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
common complaint that I hear about is missing frames when using a Mamiya C series TLR camera. Generally, this is caused by sticking shutter blades. The blades are usually sticking due to oil contamination.
Although I can usually spot the oil, it may not be easy to see the oil on the blades if you are not familiar with the issue (if you look very carefully at the first photo you can see a blue fringe on the edge of the blade). To make the issue visible, the shutter can be cooled down (a refrigerator works well) and that will cause the oil to stick the blades together. The first photo shows how the shutter will not open after being cooled. After about ten minutes on the bench, it has warmed up enough to work as seen in the second video. This is why the issue can seem so erratic with missed frames.
The only solution in cases like this is a complete disassembly of the shutter to remove and clean the blades and surrounding mechanism plates of oil.
While I see this mostly on Mamiya C series lenses, lenses for the Mamiya Universal are very similar and can act up in the same way. RB67 lenses, while still being a leaf shutter, generally stick in the open position due to a slightly different shutter configuration that keeps the shutter open when focusing.
