About 10 years ago I bought a Mamiya-Sekor C 360mm f6.3 lens for my RB67. Nice condition, all good.
Since it rarely had use I decided a while ago to try to sell it. Sadly it had a serious haze issue. The rearmost glass was dark grey - looked like an ND filter, couldn't see the shutter through it.
I took the offending item out and tried to clean it but the haze was inside, what we used to call a 'balsam fault' although it has not been balsam for a long time now I believe.
I put the glass back in and put the lens back into storage whilst I considered my options. I could look out for a lens with a shutter fault and swap rear elements or sell cheaply as 'spares or repairs'.
I retrieved it a few days ago and lo and behold the lens fairy has sprinkled her magic dust and it is cured - as clear as a bell and looking fantastic.
What happened? My best guess is that it was stored in our son's old room which is normally closed up but gets the sun in the evenings. During the recent heatwave I believe that the temperature in there has probably gone above 40C so maybe that affected the adhesive.
It would be interesting to hear any other theories which anyone has.
Since it rarely had use I decided a while ago to try to sell it. Sadly it had a serious haze issue. The rearmost glass was dark grey - looked like an ND filter, couldn't see the shutter through it.
I took the offending item out and tried to clean it but the haze was inside, what we used to call a 'balsam fault' although it has not been balsam for a long time now I believe.
I put the glass back in and put the lens back into storage whilst I considered my options. I could look out for a lens with a shutter fault and swap rear elements or sell cheaply as 'spares or repairs'.
I retrieved it a few days ago and lo and behold the lens fairy has sprinkled her magic dust and it is cured - as clear as a bell and looking fantastic.
What happened? My best guess is that it was stored in our son's old room which is normally closed up but gets the sun in the evenings. During the recent heatwave I believe that the temperature in there has probably gone above 40C so maybe that affected the adhesive.
It would be interesting to hear any other theories which anyone has.