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Half Frames / Subminiatures This forum is for all half frame 35mm cameras, including the very popular Olympus Pens and their SLR cousins, the Pen F and Pen FT, as well as all smaller than half frame subminiature film cameras.

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Cleaning Pen lenses
Old 01-12-2016   #1
mabelsound
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Cleaning Pen lenses

Impulse-bought a Pen 20/3.5 as UG from KEH on eBay: around $100. It's not here yet. Nothing in the description about glass condition (very KEH) and it looks good in the pics, but I thought I saw some haze or perhaps fungus.

Anyway, found this online and thought I'd give it a try: http://www.instructables.com/id/Clea...Lens/?ALLSTEPS

Has anyone tried cleaning this lens? Any tips?
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Old 01-12-2016   #2
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congratulations for this small little wonder. great price too! ( always envy you guys over there for that )
this lens develops a specific problem which probably effects more copies in circulation than not. I believe that the lens in the article you linked, with the very detailed instructions on how to disassemble, didn't have fungus but that very problem: the outer rim of the rear of two of the elements are painted black and this paint 'disintegrates'. If the paint is partly gone the lens will 'glow'. Furthermore this may lead to 'bubbles' covering the rear side of these elements in their optical paths and that also may influence IQ negatively. The good news is that the lens is easy to open, that these bubbles usually can be simply wiped away and the black paint repainted. I repaired one lens and later gave instructions how to somebody who had asked me for it. ( if I just would have known that linked article, would have saved me some work ) The photos I had prepared to help are still available, here the one where I show the two surfaces that need to be painted:



once you have it check the condition of your lens, if optics look clean or if you see 'bubbles'. see if you can make out if the outer rim is nicely pained black, one should be able to see that by looking at the lens from the front without having to open it, only the inner circle being clear and the rim around being uniformly black. if it needs attention and if you have further questions don't hesitate.
have fun, andreas
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Old 01-12-2016   #3
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Oh, great, thank you! very excited to try it out...I'll report back
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Old 01-13-2016   #4
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welcome and looking forward to hear about your lens

here a photo of the lens I had repaired after I had wiped away the bubbles ( unfortunately forgot to take a pic 'with' the bubbles' ) but not yet repainted the surfaces:
click on it to see it even bigger, one can clearly make out the lack of paint

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Old 01-13-2016   #5
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I bought a cheap, cloudy ebay example a while ago.

I dismantled and cleaned it following the online instructions and also removed and repainted the black as kuuan suggests.

Came out as clear as a bell.
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Old 01-16-2016   #6
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OK, well, I took the lens apart, and unfortunately the offending lens element is not the one that suffers from the shedding of black paint. The paint's intact on my 20/3.5, and that element is clean. Instead, the problem is with the tiniest lens element, on the side right behind the aperture. I figured it was just some oil that had gotten on there:

Pen 20:3.5 before by J. Robert Lennon, on Flickr

So I cleaned it with some lens cleaning fluid and swab. That didn't seem to work so I removed the element entirely and cleaned it gently on both sides with some lighter fluid and microfiber cloth. This improved matters but not by much; there are still marks on there that I couldn't get off:

Pen 20:3.5 after by J. Robert Lennon, on Flickr

After some difficulty reassembling the lens (it took a couple of tries to figure out how the aperture works; this is my first lens disassembly!) I got it back together and working again, and mounted it on my X-Pro1. Photos are a little more contrasty than before, but not up to the quality of my other two Pen lenses.

So: what now? Does Youxin service these? Or is this element simply permanently damaged?
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Old 01-16-2016   #7
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Hard to be certain from a photo, but it looks to me as if the coating itself has been affected and is partially gone. If so, you may be better off removing the rest of it, unless you are willing to have it professionally re-coated, of course. A few members have polished the coating off various lenses successfully as I recall. If this is indeed what it is (what do you think?) then, I would suggest doing a forum search for more details on the subject if you wish to tackle it yourself, so you are fully informed of the risks and benefits prior to proceeding.
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Old 01-16-2016   #8
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My guess was indeed that the coating had been partially eaten away, but I don't have much experience. Don't know the first thing about removing a coating...the idea unnerves me! Wouldn't mind hearing from someone who made it work, though. The lens element is so tiny...about the size of my pinky fingernail.
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Old 01-16-2016   #9
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Brian Sweeney recommends an "ammonia-based eyeglass cleaner" in this thread, for what seems to be the same problem...
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Old 01-16-2016   #10
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congrats on your first trial to repair a lens! but bad luck that it had been necessary, that the damage is what I also believe to be coating damage. imo removing it may or may not improve performance and will never make it perform like a good copy
I wonder just how much performance it impacted. The Pen-F 3.5/20 imo is a very good lens for a 20mm of that vintage but most likely not up to the standard of a modern 20mm or the stunning Pen-F 38 and 40mm.
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Old 01-17-2016   #11
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Yeah, it seems to have a fair amount of field curvature and distortion, so it is never going to be a precision optic. But it would be fun to get it in as good of shape as I can. In the spirit of experimentation, I really do want to give de-coating a shot. It's only one glass surface among many, what's the worst that could happen?

Well, I could completely ruin it, I guess, but...
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Old 01-23-2016   #12
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Looks like you decided to part ways with the lens on eBay.
With the "glowy" characteristic I wonder if it would be good for night B&W street photography...

GLWS!
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Old 01-23-2016   #13
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Yeah I did! Somebody in the classifieds was selling a 25/2.8 for a good price, so I decided to cut my losses on the damaged 20, and sell my 25/4 as well. It was a learning experience!
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