How do I clean a Yashica Mat-124g taking lens?

Question

I have disassembled the taking lens of my Yashica Mat-124g and tried to clean it. First, I used 99% isopropyl alcohol and it didn't help. Then I used a 1:1 solution of hydrogen peroxide and ammonia and it also didn't clean the lens.

I have realized that the problematic piece is probably a group of two glued lenses and it may be that dirt is in between the elements. Is that possible?

What other cleaner would you recommend? Acetone?

Here are some photos where you can see some haze: https://www.flickr.com/photos/radoburansky/

I believe this is how the taking lens look like: http://www.yashicatlr.com/LensesShutters.html#viewing

Answer 1

It's entirely possible for haze to come from degradation of the cement gluing two elements together, and it's really not possible to clean it. It could also be that the surface of the elements has been etched by the acid produced by fungus, and the only way to remove that is to repolish the elements, but this may change the optical character of the lens.

See this discussion thread on the mflenses forum about cleaning hazy lens elements.

Answer 2

Bit of a zombie thread but in case anyone else is looking here ... The Yashica Mat has a 4 element taking lens. The rear two elements are cemented together. They screw out quite easily from the back (provided you have a lens spanner). The front two elements are not cemented together and have an air gap that means fungus can grow in between. Once you screw the front group out (that's pretty straightforward) it is entirely possible to get these two front elements apart ... I've done it myself but it's tricky. You need to screw out the front ring (that has Yashinon etc written on it) from the outer shell. This is hard because the thread is fine and there's not much to grip on. I was successful because I wrapped rubber bands around the narrow end, liberally sprayed wd40 down into the thread and then soaked it all in boiling water for a couple of mins (that causes the metal to expand just enough to loosen the thread). After all of that i managed to screw out the ring with my lens spanner. The front element just pops out and the one behind is cemented in.