Advice on lens fog... balsam separation or oil condensation? Cost?


mark88

Link Posted 18/03/2021 - 18:55
My dear fellow pentaxians, I have a 20mm K series (12 elements in 10 groups) with fog in it. Can you help me? Is it balsam separation? Oil/grease condensation?
How much and can it be repaired?

Thanks
Marco















davidstorm

Link Posted 18/03/2021 - 19:35
My guess would be that it can't be repaired without replacing an entire element group, in which case you may as well replace the whole lens if you can find one.

Might be worth dis-assembling the lens, I've taken quite a lot of lenses apart successfully and have been able to restore them to 'good as new', but this depends on whether it is a cemented element that is causing the problem. If it's fungus or some other surface contamination you can carefully wash in dish soap and clean water, then clean after drying with Ronsonol lighter fluid and a scrupulously clean lens cloth or lens tissue, being careful to leave no smears. Wear nitrile rubber gloves so you don't get skin oil on the lenses.

Re-assemble with care, taking note of where infinity focus is set (this is easy to adjust, usually three screws that tighten onto the focus helicoid, may need a bit of trial and error to get it right).

There should be a dis-assembly guide on the internet somewhere, try Pentax Forums. If it all fails, you've lost nothing as the lens is not usable as it is.

Regards
David
Flickr

Some cameras, some lenses, some bits 'n' bobs
Last Edited by davidstorm on 18/03/2021 - 19:37

Helpful

mark88

Link Posted 18/03/2021 - 20:22
Thank David. I'm not thinking to fix it myself, I'll look for an experienced tech.

You guess it is balsam separation?

I don't think I will find another lens to get the cemented group, I have never seen another (in good condition) on sell... anywhere... (except Japan)
Last Edited by mark88 on 18/03/2021 - 20:24

davidstorm

Link Posted 18/03/2021 - 20:43
mark88 wrote:
Thank David. I'm not thinking to fix it myself, I'll look for an experienced tech.

You guess it is balsam separation?

I don't think I will find another lens to get the cemented group, I have never seen another (in good condition) on sell... anywhere... (except Japan)

Hi Mark

I don't know without being able to see the lens and take it apart. I don't think it's oil, it could be a type of fungus, there are lots of different types that can look like haze, if it is fungus it will be clean-able so long as it hasn't etched the glass. Which exact lens is it, also how long has it been like this?

Regards
David
Flickr

Some cameras, some lenses, some bits 'n' bobs
Last Edited by davidstorm on 18/03/2021 - 20:44

mark88

Link Posted 18/03/2021 - 20:45
SMC PENTAX 1:4/20 the early K mount 20mm with 12 elements in 10 groups
http://kmp.pentaxians.eu/lenses/ultra-wide/k20f4/


Just bought, arrived today. I'm looking if its fixable before sending it back. (Seller told it was perfect, fluid, clean, bla bla bla.. )
Last Edited by mark88 on 18/03/2021 - 20:46

davidstorm

Link Posted 18/03/2021 - 20:49
Hi Mark

I would think that one will be quite easy to dis-assemble. I would be happy to take a look at it if you like, I wouldn't want to charge any money, would do it as a favour.

I'm not a professional tech, but I have repaired lots of lenses over the years and I don't take risks if the lens is difficult to take apart.

If you send it to a tech, you may end up spending a lot of money for no end result.

Regards
David
Flickr

Some cameras, some lenses, some bits 'n' bobs

davidstorm

Link Posted 18/03/2021 - 20:52
Hi Mark

Just re-read your post, i.e. that you received it today. Send it back immediately, it's not your risk, the seller should have disclosed it and would have been aware of this.

Regards
David
Flickr

Some cameras, some lenses, some bits 'n' bobs

Helpful

mark88

Link Posted 18/03/2021 - 21:47
Thanks David, appreciated!
Just a pity this gem will not live again.

cardiffgareth

Link Posted 18/03/2021 - 21:52
Watch the seller on ebay, it might go back up for spares. If you buy it cheap then you don't mind taking the punt. Old Pentax lenses, especially primes are dead easy to take apart, just be methodical with what came out, in what order and what way around!

I use 99.9% isopropyl alcohol and use that to rub the optics. Proper kills the fungus in its tracks!
Gareth
Welsh Photographer

My outfit: K1 gripped - Pentax D FA 24-70mm - Sigma 70-200mm OS HSM - Pentax modified DA* 60-250mm f4 - Irix 15mm Firefly - Sigma 50-500mm - FA 50mm f1.4 - Tamron SP 90mm macro - Pentax AF 540 FGZ Ii

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davidstorm

Link Posted 18/03/2021 - 22:51
Hi Mark

I have sent you a private message that may assist you with your issues with this lens.

Regards
David
Flickr

Some cameras, some lenses, some bits 'n' bobs

mark88

Link Posted 18/03/2021 - 23:55
Thanks

womble

Link Posted 20/03/2021 - 22:55
The K20 is indeed a rare(ish) beast. There was one listed on the US fora with "worldwide postage" but then refused to send it out of the US when I enquired. I may well have to bite the bullet and buy one from Japan.

I hope you can get it sorted.

Best wishes, Kris.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

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mark88

Link Posted 21/03/2021 - 12:03
Nope, heard a technician and the response is its a very risky operation. So I sent it back for refund.
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