Mamiya 7 150mm Lens: Finding Fungus Behind the Closed Shutter
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
Another fungus post. This 150mm Mamiya 7 lens came into the shop for a rangefinder check. While the rangefinder checked OK, I did notice fungus on inner surfaces of both the front and rear lens element groups. On the Mamiya 7/6 lenses, fungus is not so easy to notice as the lens shutter is normally in the closed position so you need to install the lens on the body and hold it open on “B” to check.
I found the fungus on the rear elements (photo two) to be quite unremarkable. It cleaned off fine. But the fungus on the front element group (photo three) was quite interesting. You might not think so from this photo, but under 60X magnification it was quite glorious looking as seen in photo four. I almost hated to clean it off but of course, it had to be done. After cleaning and UV-C treatment, it is mostly gone but it did do some permanent damage to the glass visible as a very light stain if you look very closely. Probably been living quite happily on this coating for a long time as I was told this lens did not get much use so sitting with lens caps on in a humid location was just the right conditions for this growth.
