Mamiya 7 80mm Lens: Condensation Haze in Rear Element Group
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This Mamiya 7 80mm lens came into the shop from over the ocean (Brisbane to be exact) with a complaint of haze in the rear element assembly.
Often, with haze on these particular lenses, the issue is between the cemented elements and is not easily fixable. Fortunately in this case, my client told me that the camera and lens had been in hot and humid conditions recently and that the lens was not hazy before then. So, this is good news as it tells me that the issue is probably condensation that can be cleaned after the lens is disassembled.
Photo two shows the rear group removed from the lens and with a light shining through condensation is visible. After the lens group is disassembled a bit to remove the rear element, I put them all (including the lens barrel and shutter ) in a PCR workstation enclose with plenty of silica gel and get the humidity down to around 15% . After a day or so in the enclosure I reassemble the lens. And, I do run the UV-C light in the box for a couple of hours to kill any organisms as I don’t want to add to the microbe load in the lens. All of this may be a bit extreme but my feeling is that these particular lenses (80mm f/4 produced from 1995-2000 or so) are very often found with fungus between the cemented groups and I wonder if it had anything to do with air quality when the lenses were being produced at Mamiya Japan? So, since I don’t have a level one cleanroom for lens assembly, my little enclosure will have to do.
