Cleaning internal surfaces of a lens element

[Dr Bellows]

Hi all,
I have a Schneider Symmar 150mm ƒ5.6/256mm ƒ12 convertible that has haze on the internal surfaces of the rear element. I made a spanner to pull the retaining ring so now I can clean it, but I thought I would ask here first if there are any precautions to take with respect to the cleaner used or other things I may not have thought of. I have Kodak lens cleaner, isopropyl alcohol (70 & 90%) and denatured ethyl alcohol.

Thanks,

Scott

[John Schneider]

I have the best luck with reagent-grade xylene (use gloves and good ventilation). Anything that is miscible (such as acetone and alcohols) tends to pull water out of the air (even here in the desert) and cause streaking.

[Steve Goldstein]

Some people swear by a product called ROR (Residual Oil Remover), available from B&H among other places. I use and like Pancro fluid, sold by Filmtools. Edmund Scientific also sells solutions for cleaning technical optics.

I disliked the Kodak solution at it always seemed to leave streaks. Pancro will too, the trick is to use it sparingly, applied to the lens tissue, not directly to the glass.

Oh, and I use Rosco lens tissue, it's what the Hollywood guys use and guaranteed not to scratch coatings. It's also sold by Filmtools. Kodak tissue feels much coarser by comparison.

[Pete Watkins]

In the 70's I worked as a repairer of surveying instruments, we used ether. I don't know if it's available now, but I use lens cleaners from a chain of chemists shops (might be drug stores over there) and they recently did wonders for a 1930's TT&H Aviar.
Pete.

[patrickjames]

The old ROR was great but I read the formula kicked it with the originator and it smells different now. If you really want to get the lens microscopically clean it is best to use Opti-Clean but it is expensive. Amazing stuff. I have read that you can use collodion as well but I haven't tried that. I use Opti-Clean on interior surfaces and Carl Zeiss or ROR on exterior ones.

[Dr Bellows]

By the way, it is amazing how tight the element retaining ring was. I did not see any sign of loctite or varnish in the threads and it unscrewed with a gradually reducing torque as I would expect from something that was just plain tight. I'm glad I used a ring spanner instead of an adjustable - I could easily visualize and adjustable slipping out of the grooves and scratching the lens.

Is there any good reason to make it that tight when I put it back together?