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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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08-19-2017, 10:08 PM   #151
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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, 09:27 AM   #152
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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.
01-10-2018, 06:01 PM - 1 Like   #153
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What you're probably talking about is the introduction of "color centers" in the glass caused by the radioactive nature of the Thorium (and possibly some of the rare earths or other doping substances used in the glass formula).

There's an industry devoted to coloring diamonds using radiation (the diamonds are placed in a nuclear reactor). In the case of glass, the reaction can be reversible (hope not for diamonds - your girl's favorite chocolate colored diamonds just faded - yikes!!). Since the Thorium is in intimate contact with the glass, its radiation is fairly intense at atomic distances.

The same effect is responsible for turning old glass purple tints (those old purple bottles on the antique store shelf) and some glass bluish-green (telegraph pole insulators) due to sun exposure and the presence of some elements in the glass (newer glass is resistant to this).

I once radiated vegetable seeds in a cobalt (gamma) cell and my clear plastic containers came back purple (seeds came back dead)

For more if you're interested (heavy stuff):

Activation of color centers in Glass

Last edited by Bob 256; 01-11-2018 at 08:45 AM.
01-16-2018, 09:27 AM   #154
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QuoteOriginally posted by Chaos_Realm Quote
Pentax Lens Disassembly Database
This has got to be the scariest thread on the forum... for folk like me with two left hands and fingers like bananas.

02-26-2018, 02:14 PM   #155
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Hi, is this thread (or the sticky first part) still being updated? I was looking for a guide for the M 50mm F4 macro, and can't find one, but I did find one for the F1.7, which doesn't seem to have any here, so if active, feel free to add it: Shooting with a Pentax K10D: Cleaning from fungus: SMC Pentax-M 50 f/1.7
02-26-2018, 02:44 PM   #156
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QuoteOriginally posted by Kerrowdown Quote
This has got to be the scariest thread on the forum... for folk like me with two left hands and fingers like bananas.
I have similar fingers but I do have a right and left hand

and a habit of asking myself after I have reassembled some thing that I took apart

" I wonder if that left over screw (s) is ( are ) important or can I just throw it ( them ) away "

" some assembly required " is, to me, some of the scariest language I have ever encountered
02-26-2018, 02:52 PM - 1 Like   #157
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QuoteOriginally posted by Aslyfox Quote
I wonder if that left over screw (s) is ( are ) important or can I just throw it ( them ) away
I put all those bits from everything into one box... after a while I can't remember where they all came from, so then it's safe to bin them.

Highland logic.
02-26-2018, 03:09 PM - 2 Likes   #158
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QuoteOriginally posted by Kerrowdown Quote
I put all those bits from everything into one box... after a while I can't remember where they all came from.
When I do that, I eventually have enough parts for a whole new lens.

02-26-2018, 03:19 PM - 1 Like   #159
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QuoteOriginally posted by asharpe Quote
I eventually have enough parts for a whole new lens.
I never thought of that... old car parts, old watch parts... it's gonna be a fine looking lens.
02-26-2018, 04:11 PM   #160
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some one should make a song out of that idea

johnny cash cadillac song video - Bing video
04-21-2018, 02:49 AM - 1 Like   #161
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I'd like to vote this thread to be a sticky
04-22-2018, 06:39 AM   #162
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QuoteOriginally posted by angerdan Quote
I'd like to vote this thread to be a sticky
Might use a little "cleaning up" first for those off topic posts. I tried to get a few guidelines on posting to this thread (Pentax FA 28-200mm lens repair), but never heard back. (Would like to know how to format for photos & text etc.)

Anyway, I second that proposal.
04-22-2018, 09:31 AM   #163
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With Free BBCode Table Generator Tool it is even possible to use tables.
Other useful tools are AnyToBB and HotEditor V4.4 - WYSIWYG to BBCode Converter (HTML to BBCode and BBCode to HTML) Support Safari.
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DA 40mm ltd lens repair

QuoteOriginally posted by RedMist Quote
Does anyone have experience of disassembling a DA 40mm Ltd lens?

The smaller ribbed centre section around the lens opening within the name ring can be removed and reveals 3 little screws but I'm not sure if there are more screws lurking under the name ring. Maybe the name ring on the 40mm doesn't remove as it does on the 21mm due to the smaller lens opening and therefore different design?

TIA
Hi,
I saw this question on here from a few years ago that was never resolved regarding a DA 40mm limited pancake.

After buying one off of ebay it didn't take long to essentially fall into two pieces after the three screws holding the screw focus in came loose and fell out. The previous owner must have bathed it in sand as it was full of the stuff and probably caused/assisted the screws to come out.
I have a good idea on how it goes back together but I can't get the small ribbed centre section out to reveal the three screws underneath.

Can anyone provide any light on this?
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