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Pentax Lens Disassembly Database
Posted By: Chaos_Realm, 03-22-2012, 05:04 PM

Hi all,
I have recently been on the hunt for dis-assembly guides for the purpose of dust removal etc. They seem to be turning up in various places across the forum, so I plan on creating a list of all the Pentax lens disassembly posts here. I will categorise each lens like they are in the 'lens database' and you should be able to see which lenses have a guide and which do not. If I come across multiple guides then I will list them all under that lens so there is coverage or alternative explanations. And hopefully with your help we will be able to put together a substantial resource for the DIYer's here, although I do realize some lenses will never have an owner brave enough to strip down themselves due to the shear value. I know this will take quite some time but I think it will be worth it. I have restricted time at this point but I want to get the ball rolling. So here is what we have:

NB: Currently this tread is only for Pentax K-Mount & M42 Screw-mount lenses. Maybe once this has developed a bit I might look at introducing other pentax Mounts and or third party lenses and permitting time (and success of this resource) a cleaning guide with tips on tools and techniques. I am trying not to bite off more than I can chew for the moment so we will just stick with lenses listed below.

Digital Era K-mount Lenses Film Era K-Mount Lenses
M42 Screw Mount Lenses


Last edited by Chaos_Realm; 04-22-2017 at 07:27 PM.
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07-03-2017, 10:34 AM   #151
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QuoteOriginally posted by niceshot Quote
getting to the lens element is not a problem but, I THINK it is lens separation. Only way to rule it out is to open it up and clean the lens groups involved. It is in a Bad spot ,meaning it will impact the Image quality, So you have nothing to lose, try cleaning it. Start off using Zippo lighter fluid and finish off with alcohol. Also use Kim wipes. Remember to brush then blow then wipe. A friction wrench should be able to loosen it if not then a Lens Spanner wrench . Good Luck
It's got all the fibers and texture that make me think fungus.

My fear is that taking it apart means I won't be able to get it back together. Using the lens a bit, I've seen some impressively sharp shots around F7-8, which lead me to believe that it doesn't influence image quality too much. My guess is that, at worst, it makes wider aperture shots more glowy.

If I were to attempt cleaning, I would very much like to have a parts diagram, at least. I'm sure the 1.7 lens is similar, but not quite the same.

07-03-2017, 10:43 AM   #152
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QuoteOriginally posted by timw4mail Quote
It's got all the fibers and texture that make me think fungus.

My fear is that taking it apart means I won't be able to get it back together. Using the lens a bit, I've seen some impressively sharp shots around F7-8, which lead me to believe that it doesn't influence image quality too much. My guess is that, at worst, it makes wider aperture shots more glowy.

If I were to attempt cleaning, I would very much like to have a parts diagram, at least. I'm sure the 1.7 lens is similar, but not quite the same.
SMC Pentax-A 50mm F1.2 Lens Photo - Pentax Lens Reviews & Lens Database here you are
07-03-2017, 10:36 PM   #153
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Looks like fungus. With such a nice lens, I'd be inclined to send it to a pro. It looks easy, but they have the right tools. I've been in a few lenses, but I try to stick to the ones that don't cost a lot, in case I have problems. You'll lose the cost of the pro cleaing of that element just by marking up the spanner ring, it seems to me..
07-04-2017, 04:00 AM   #154
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QuoteOriginally posted by Ranchu Quote
Looks like fungus. With such a nice lens, I'd be inclined to send it to a pro. It looks easy, but they have the right tools. I've been in a few lenses, but I try to stick to the ones that don't cost a lot, in case I have problems. You'll lose the cost of the pro cleaing of that element just by marking up the spanner ring, it seems to me..
you can touch up lens spanner marks with magic marker, but it is best to use a friction wrench, Also this thread is for people who want to do it for themselves. Although I think that gentleman will probable heed your advice.

07-04-2017, 06:47 AM   #155
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What do you use to clean of the fungus of the inside elements? Zippo fluids? 70% rubbing alcohol?
07-04-2017, 08:01 AM - 1 Like   #156
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QuoteOriginally posted by Theov39 Quote
What do you use to clean of the fungus of the inside elements? Zippo fluids? 70% rubbing alcohol?
I personally use zippo to remove and loosen up every thing first ,then i finish up with 91 percent alcohol from cvs or where ever. You could use acetone then alcohol also but I like Zippo better. Also use Kim Wipes ,and after it drys use bulb blower to remove any lint. But you don't have to be acod about it. Remember less is more when cleaning, lest you could scratch it. Also remember to blow then brush then clean.
07-04-2017, 12:50 PM   #157
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Thanks for that. I thought Zippo fluid might have been too strong and potentially damage the coating on the lens.
07-04-2017, 02:00 PM   #158
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For fungus I use hydrogen peroxide, then Zippo lighter fluid, I don't blow off anything if I'm cleaning fungus until I've hit it with the peroxide. I finish with acetone. Just enough on a qtip so it evaporates almost immediately, you don't want acetone running into the seam between a retaining ring and the element. It will remove edge blacking, blacking on retaining rings, and melt plastic. niceshot, if I want to suggest the poster might want to take his lens to a pro, I'll do so.


Last edited by Ranchu; 07-04-2017 at 03:48 PM.
08-11-2017, 07:41 PM   #159
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QuoteOriginally posted by Theov39 Quote
Thanks for that. I thought Zippo fluid might have been too strong and potentially damage the coating on the lens.
I have heard that some of the older lenses repeated use can damage the coatings, but I have yet to see any ill effects. it probably depends on the particular coating on the lense. SMC has been fine so far.
08-11-2017, 10:30 PM   #160
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I think that is a porky. Many materials may age, based on environmental effects on them in storage or in use. But the conditions of use of a lens are petty benign - the photographer must withstand the same conditions, and use is actually quite a short time. Use might expose them to conditions, such as dust and dirt, and the remedial actions might be the cause of deterioration.

Anyone have evidence of the claim of use induced deterioration?
08-12-2017, 11:19 AM   #161
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QuoteOriginally posted by Chaos_Realm Quote
I have heard that some of the older lenses repeated use can damage the coatings, but I have yet to see any ill effects. it probably depends on the particular coating on the lense. SMC has been fine so far.
The coatings are made of Magnesium Fluoride, so quite resistant. And a lot of service manuals to Lens say to use petroleum ether and alcohol mixture. 70 - 30 mixture
08-19-2017, 07:28 PM   #162
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QuoteOriginally posted by tim60 Quote
I think that is a porky. Many materials may age, based on environmental effects on them in storage or in use. But the conditions of use of a lens are petty benign - the photographer must withstand the same conditions, and use is actually quite a short time. Use might expose them to conditions, such as dust and dirt, and the remedial actions might be the cause of deterioration.

Anyone have evidence of the claim of use induced deterioration?
QuoteOriginally posted by niceshot Quote
The coatings are made of Magnesium Fluoride, so quite resistant. And a lot of service manuals to Lens say to use petroleum ether and alcohol mixture. 70 - 30 mixture

I have not seen any evidence and I use it myself, but I raised the point so that anyone reading can consider it and investigate for themselves. Given I know nothing of the chemical composition of coatings I wouldn't like someone to potentially destroy their lens because "someone on the internet told them to".
08-19-2017, 10:08 PM   #163
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This discussion brings the question - what actually yellows in the thorium lenses? This puzzles me because it can be corrected by exposure to UV light.

Is it a product of radioactive decay in the glass. Sounds implausible because UV cannot reverse the nuclear decay.
Is it a chemical change in the glass or in the coating, where the energy in UV is enough to reverse the process?
08-20-2017, 08:54 AM   #164
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QuoteOriginally posted by tim60 Quote
This discussion brings the question - what actually yellows in the thorium lenses? This puzzles me because it can be corrected by exposure to UV light.

Is it a product of radioactive decay in the glass. Sounds implausible because UV cannot reverse the nuclear decay.
Is it a chemical change in the glass or in the coating, where the energy in UV is enough to reverse the process?
It is the glass. Google "radioactive browning." I had a discussion with one of the experts on this, and he speculated that the UV was enough to reset the energy states of the ionized elements in the glass that cause the browning. He also mentioned that heat is typically used to clear browning, so it might have a role as well.

It's the same concept as color change glasses, which are designed to be much more easily ionized, causing darkening, with unstable states that reset themselves when solar radiation is removed.
08-20-2017, 09:27 AM   #165
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dcshooter: that makes sense. Ionising the other atoms is plausible as a radioactive event effect. The ionisation effect is likely to involve electrons with UV energy levels. Suggests broad spectrum UV, such as sunlight, is likely to be more effective than a single element discharge source unless that is the same element as the one that was ionised. At least with broad spectrum, some photons will have the right energy level to cause the right band jumps to occur.


One of the first people to study that in detail (Moseley?) from Oxford, was killed at Gallipoli, 1915.
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