Auto Chinon 55mm Macro 1.7- Cleaning help and advice please

StillSanj · Joined: 21 Apr 2015 Posts: 412 Location: United States

Hey guys. A while ago I got a Chinon CM-3 camera for $40 dollars, and it just so happens to have a Auto Chinon MCM Macro 1.7 on it.

I really like the lens for it's somewhat Macro potential as well as fast aperture. The aperture blades work like a charm, and that was a common problem with these lenses. However, it is rather soft in its bokeh and doing the flashlight test, I noticed that it's front element is rather dirty. I'm not sure if its fungus or what, but it seems rather salvagable to me. The image quality is not that bad, but since I really like the lens and paid so little for it, I would like to see it at it's full potential. Here is the damage..

My question is mainly 3 fold....1) is the lens worth cleaning? or is it even salvagable, and that is as good as it gets and I should just kill the fungus, if that is fungus, with UV and use lens as it is? 2) Is the lens easy to clean/disassemble? Does anyone have any experience or knowledge in this, or how much it differs from the regular Chinon 1.7? and 3), If it is advised to get it CLA'd or serviced, does anyone know a decent person or service in the Nebraska area? Or is someone here a helpful camper that would take the services upon themselves for a decent friendly fee? Thanks in advance guys, I could really use your help.

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calvin83 · Joined: 12 Apr 2009 Posts: 7495 Location: Hong Kong

I would suggest you get a non-macro version and swap all the elements.

cooltouch · Joined: 15 Jan 2009 Posts: 9109 Location: Houston, Texas

I gotta disagree with Calvin on this one. Your lens looks like it's dusty, has some haze, and even fingerprints, but I see no signs of fungus from the photos you show. With the right tools, you should be able to clean the inside of that front element yourself. Most likely to get to the front element, you will need a large rubber stopper that will fit snugly against the lens's nameplate/bezel in front. You should be able to unscrew by pressing the rubber stopper firmly against it and then rotating counter-clockwise. Chances are, beneath this bezel there will be a slotted retainer ring, and you will need a lens spanner to loosen it. Don't try using two screwdrivers or anything but the proper tool because the chance of scratching the front element is too great. You can find lens spanners on eBay. The good ones aren't cheap, but they'll last a lifetime. You can find the rubber stoppers for lens disassembly on eBay too. Other than that, maybe a chemistry supply. Once you've unscrewed the retaining ring, the front element will probably fall free. So just do your best job at cleaning it and then put things back together in the reverse of disassembly.

calvin83 · Joined: 12 Apr 2009 Posts: 7495 Location: Hong Kong

Michael. I suppose the OP will try to clean the lens before purchasing another copy for elements swapping. Rolling Eyes

cooltouch · Joined: 15 Jan 2009 Posts: 9109 Location: Houston, Texas

Yeah, I would. He doesn't have anything to lose, really.

StillSanj · Joined: 21 Apr 2015 Posts: 412 Location: United States

Hey thanks for your guys input! I'm rather novice, but it seems to me to not be fungus, and if it is, I do not believe it is etched in the glass. Also, it is almost only the front element as the other elements seem to show hardly any wear except minor dust, and luckily, from your instructions, that doesn't seem to be too hard to disassemble. I have never cleaned or disassembled a lens before, but I'm a pretty patient and focused guy. I believe I will look around for someone that has more experience, but if I do not find anyone, I will take you up on your instructions and try to clean it myself. Thank you cooltouch! Also, do you by any chance have any suggestions as to what to clean it with? I've heard all kinds of things out there, but you seem like a knowledgeable guy, so I'd probably give your suggestion a chance. Thanks again.

vroger · Expire: 2016-10-21

sent a pm

StillSanj · Joined: 21 Apr 2015 Posts: 412 Location: United States

cooltouch · Joined: 15 Jan 2009 Posts: 9109 Location: Houston, Texas

I'm glad you found a guy, StillSanj. For your future reference, the only thing I use when I'm doing a final lens cleaning is lens cleaning solution. I may use alcohol or naphtha during earlier cleaning phases, but to put the final spotless shine on a lens, just regular old lens cleaner and lens tissue is all you need.