Nikkor-O 35mm f/2

[Erik Lund]

Most likely the very high humidity in Japan.

[richardHaw]

Most likely the very high humidity in Japan.

probably. as glass contract and retract, the cement would crack.

if i have seen 2-3 samples that have a similar problem, i will assume that that is common for that lens. for example, the original 300mm f/4.5 lens almost always have weird marks on the rear element when you see them in junk shops. I have seen 4 of them that have it including mine.

[Erik Lund]

Well you do also see a huge amount of lenses over there, here in most countries in Europe we don't have piles of lenses in the shops, very few camera shops have old lenses in stock,,, Nothing like B&H, Adorama or KEH here,,,

[Roland Vink]

Early multicoated 35/2 lenses (C and K types) seem prone to separation between the cemented elements. I have a Nikkor-O.C with separation - a nice shimmering ring around one of the inner elements. I used to have two K 35/2 (with consecutive serial numbers - purely by chance!) and both had separation. One had a brighter reflection more or less on one half of an inner element, the other appeared to be completely separated with a fully circular reflection in the same place. I have not seen separation like this on other lenses so it seems be be quite rare.

[pluton]

Could it be that the 35/2 was one of the last holdouts in the use of the old botanically-derived cements between elements?  Did they switch to the newer, longer-lasting synthetic cements in the later Ai/AiS versions?  Is there any way to know?

[Erik Lund]

Yes, if you put the lens elements in hot water the Canada Balsam will let go and the two elements a free of each other again, not so easy done if [UV] cured Epoxy was used 

[richardHaw]

Some people here fix that by heating the doublet in top of space heater or hair dryer  success rate seems to be high. An Indonesian guy messaged me and I gave him that advise and it worked. It seems to work best when the separation happened at the edges and looks lkke a rainbow.  Try it! Just heat the doublet with a hair dryer for about 5-10minutes on low heat continuously. As soon as the rainbow went away stop!

[Harald]

Nice.

Harald

[richardHaw]

Nice.

Harald

OMG! i forgot all about your grease!

[Erik Lund]

To have a uniform heating of the lens elements I strongly suggest not to use a hair dryer, instead immerse in room temperature water and heat it up slowly until separation then clean while in the water.

[Harald]

Hi Richard,

no problem. I can wait. I will get my sample (But a K-Version) this week.
Erik, should he use ab bag for the lens?

Harald

[Erik Lund]

You disassemble the lens first,,, 

[richardHaw]

Yes, if you put the lens elements in hot water the Canada Balsam will let go and the two elements a free of each other again, not so easy done if [UV] cured Epoxy was used 

how would you separate the modern ones? acetone?

there's this guy, who fixed his modern canon AF lens' rear elements by heating it in hot water despite me telling him NOT to and use a blow dryer!
so far it got fixed and he is happy. i have no idea what canon uses on their lenses but this was what happened.

[Erik Lund]

Heat also makes the Epoxy soft and gum like,,,

[Peter]

So the question that hasn't been asked is.
What do you do to glue the elements back together?