[SunnyG.]

before attempting to open up the lens, you may want to review this thread:

Cross-head screws - a caution: - PentaxForums.com

Thank you very much! That's very useful and interesting!

---------- Post added 03-08-19 at 10:56 PM ----------

It's been a great tool for me with zero problems. Unfortunately, acetone CAN take coatings despite assurances to the contrary. There are forms of nail polish remover that are non-acetone but I find that isopropyl alcohol works well with zero issues. Also, if it doesn't work you can then try (at your own risk) acetone - but if it does then you avoided any potential risk with the acetone.

I won't use acetone! Don't want to damage my lens. Just need to clean it!

---------- Post added 03-08-19 at 11:01 PM ----------

I would be extremely careful using ACETONE as it will dissolve a lot of plastics Quote from B&H Photo
"Do not use acetone. Acetone is a great cleaner, but, when used on camera lenses, it could have adverse effects on the plastic and paint of the lens barrel, as well as the optical coatings. Again, do not use acetone."
How to Clean Your Lens and Filters | B&H Explora

Personally I have used ACETONE to WELD plastics together!

Photo Camera In Acetone - YouTube

Those are all the basic cleaning methods. I tried :/

---------- Post added 03-08-19 at 11:07 PM ----------

So you have 4 copies total? You could use one to donate a rear element if needed. I've not worked on this specific Vivitar lens, but I have torn into I think a similar age Series 1 28-105. To get into that lens, I had to start by unscrewing the rear mount. I was basically able to feel my way through by just removing the next piece down as I went deeper and deeper. So, get a nice clean work area where you can spread out and just go at it. I'm going to guess that you're going to find that element held in place by a part that's going to need a lens spanner. Here are some samples:

amazon.com: lens spanner?tag=pentaxforums-20&

Regarding fluids to clean lenses, as already mentioned, stay away from acetone. Most cleaners seem to have alcohol or ammonia in them. You can search for the MSDS sheets and get an idea of what's in them. Here's a search for them for Eclipse:

MSDS Eclipse lens cleaner at DuckDuckGo

Of note, on some of my newer Pentax lenses (believe it was the DFA 15-30), there is actually a card saying not to use cleaners with alcohol.

And this may be of use - from Lens Rentals on what they do:

Lens Rentals | Blog

I also thought of exchanging rear element. But then I thought if I can open it. I can try to clean it first. And if it doesn't work, maybe then I can try to exchange them. And thank you for the links, they are really helpful!

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I also thought of exchanging rear element. But then I thought if I can open it. I can try to clean it first. And if it doesn't work, maybe then I can try to exchange them. And thank you for the links, they are really helpful!

Most welcome on the links etc. Yes, if you get it apart, I'd try cleaning it first. I was just thinking if it couldn't be cleaned, you had a source of parts. Post back your results - want to see a success story! It's a lot of fun working on vintage lenses and bringing them back.

[SunnyG.]

Most welcome on the links etc. Yes, if you get it apart, I'd try cleaning it first. I was just thinking if it couldn't be cleaned, you had a source of parts. Post back your results - want to see a success story! It's a lot of fun working on vintage lenses and bringing them back.

Hahaha I will definitely post the results. Lots of useful information on the lens in this post! One of the best photographic forum!