Originally Posted by Dave S.
Thanks everyone for all of your helpful responses.
Brian: Thanks for your comments regarding "rainbow from Balsam separation- Newton's Rings"
. This is not what I'm seeing in this lens so perhaps it's just bubbles.
It also sounds like balsam deterioration / lens separation is seen more around the edges of elements - even if sometimes it presents as more "faint, greyish cloud"
than rainbow (thanks Frontman).
Beemermark: For me personally, I enjoy taking pictures and
learning about the minutiae of classic cameras and lenses - stuff like balsam deterioration, bubbles in lens elements, etc. (in a kind of Zen and the Art of Motorcycle Maintenance
That said, I took your advice and have attached a few pictures of my Solagon 1:2/50.
Does this look like bubbles
or balsam separation?
The bright pin-points of light towards the center of the glass look like bubbles, or "seeds" as the window-glass people call them.
The cloudy-ish parts of the lens, around the lower part of the glass, say from about 1 o'clock over to 7 o'clock look like some other sort of deterioration - perhaps balsam, maybe fungal etching, or coating damage...
The "clouding" might cause some flare if you are shooting w/o a hood or against strong light....
Most of the balsam failure I have personally experienced has been with pre- WW-I lenses, and usually starting as a ring around the perimeter... stopping-down 1 stop usually masks the separation.
I do have a Takumar 55/1.8 from my 1960's Pentax SP-500 that has dramatic balsam failure, intruding nearly 1/2 into the center of the lens, about 60 % of the way around the glass...
Just my impression for looking at your pictures...