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01-06-2020, 06:16 AM - 1 Like   #1
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50mm 1.2 with weird dots inside lens - What is the damage and where to get fixed?

EDIT: I was able to clean this myself thanks to your help, here's a video explaining how:


Hello all,

I'm sure someone can tell what this is quickly and explain it to me, I've just never seen it before. My 50mm 1.2 has TONS of little dots on the inside of what appears the front element. This makes the lens lose a lot of contrast and get really glowy, especially with highlights. From what I can tell on the internet it could be some oil from the lens that gets dispersed or potentially a coating problem? Still pretty confused.

I bought the lens from Japan, this was not disclosed, the seller profusely apologized, refunded me the money, and said I could keep the lens. (Yeah, I know, crazy). So now I am searching for a way to get it cleaned professionally. I am seeing a good list of repair places on the sticky thread here, but I wanted to know what it was before I started asking for quotes. Also, if you have any recommendation of a place to take it that is welcome as well.

Thanks!

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Last edited by Snapppy; 01-07-2020 at 08:33 PM.
01-06-2020, 06:36 AM - 1 Like   #2
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That looks like it's on or affecting one of the front elements. Often that sort of appearance to me says deteriorated balsam cement, but these front elements are not cemented judging from the optical diagram in the reviews. My guess is some sort of haze. Over long periods of storage you can get something like a condensate on an element - likely source volatiles in the the lubricants used on the focus helicoid.
This is quite likely to be an easy clean by removing the nameplate and the front elements.
It could also be fungus, you can get spotty rather than tendrilly fungus.
I use acetone (nail varnish remover) on haze, meths with a drop of detergent (mould and mildew cleaner) on fungus, cheap optical wipes from the supermarket.

Last edited by marcusBMG; 01-06-2020 at 07:19 AM.
01-06-2020, 07:57 AM   #3
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If you clean it let us know if it was easy, I have one I'd like to clean and if I get the front clean that'll be a good start. What tool would remove the front plate?
01-06-2020, 08:00 AM   #4
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Never seen that before. In the second picture it looks like some cleaning marks. Maybe a previous attempt? I would try removing the front element and see if it is like condensation that can be cleaned.

Thanks,

01-06-2020, 08:13 AM - 2 Likes   #5
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Maybe fungus.
I would think that removing the front ring would be similar to other older pentax lenses where some double sided tape applied to a rear lens cap would be a good device to get grip on the ring. I've done that with some old M42 mount lenses with fairly good success.

As far as what to clean it with I would try some rubbing alcohol or denatured alcohol first as they are pretty mild and will kill a lot of things and are a good solvent for a lot of things while being pretty mild. If no success then start moving up going to more aggressive ones like methanol or diethyl ether next as they are still pretty mild but are more aggressive and ether is really good a getting rid of oil. From there I'm not sure what I would try as I would be worried about stripping the coatings going up to to things like mineral spirits, lacquer thinner, acetone, and then toluene/xylene. That is usually my progression for solvents.
01-06-2020, 08:55 AM   #6
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QuoteOriginally posted by ChristianRock Quote
If you clean it let us know if it was easy, I have one I'd like to clean and if I get the front clean that'll be a good start. What tool would remove the front plate?
I found a good thread on here show pics of the disassembly. Seems like you can take the little bezel off that hides the notches on the front ring by some screws that are hidden underneath a little decorative ring attached to the focusing ring. Getting there is a little tricky though. I've thought about the double-sided tape method or high-grip material to get the front ring off without having to go through all that. Still not sold on me doing this myself until I feel sure I know what it is, haha.

https://www.pentaxforums.com/forums/114-maintenance-repair-articles/278469-p...mbly-pics.html

Thanks for the other tips and replies. It's very helpful.
01-06-2020, 09:59 AM - 1 Like   #7
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QuoteOriginally posted by Snapppy Quote
I found a good thread on here show pics of the disassembly. Seems like you can take the little bezel off that hides the notches on the front ring by some screws that are hidden underneath a little decorative ring attached to the focusing ring. Getting there is a little tricky though. I've thought about the double-sided tape method or high-grip material to get the front ring off without having to go through all that. Still not sold on me doing this myself until I feel sure I know what it is, haha.

Pentax K 1.2/50mm Disassembly pics - PentaxForums.com

Thanks for the other tips and replies. It's very helpful.
Lens Ring Tool Set Sizes 13,19,21,24,29,30,36,37,44,45,54,62
01-06-2020, 10:11 AM - 5 Likes   #8
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The front ring on this lens CANNOT be simply screwed off. I've personally seen enough examples of this lens with drilled holes and I also destroyed the front from one example because I was adamant on unscrewing the front. It's actually fixed to the body and can only (READ EDIT) be accessed from the rear of the lens.

(EDIT: There is a decorative bezel on the top edge of the focus ring that can be unscrewed, giving access to three screws that hold the front housing. Removing these screws gives you access to the front elements without fiddling with the rear of the lens)

The dots you see are simply condensation spots. It'll take you a minute or two to actually get those removed. I usually breathe on the element and wipe with a clean glasses cloth (microfibre). If you need chemicals, pure methanol is perfect and won't leave streaks. Wipe with a wet (methanol) lens cloth, clean off with a dry lens cloth.

To those mentioning balsam separation - the rear of the lens has the cemented group and can often separate. This barely impacts IQ unless the separation progresses deeper into the element group.

Source: Loads of K and A 50/1.2 lenses.


Last edited by HarisF1; 01-08-2020 at 06:02 AM.
01-06-2020, 10:42 AM   #9
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QuoteOriginally posted by HarisF1 Quote
The front ring on this lens CANNOT be simply screwed off. I've personally seen enough examples of this lens with drilled holes and I also destroyed the front from one example because I was adamant on unscrewing the front. It's actually fixed to the body and can only be accessed from the rear of the lens.
I did not know that but now I do. so I guess my assumption was wrong.
01-06-2020, 10:47 AM   #10
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QuoteOriginally posted by HarisF1 Quote
The front ring on this lens CANNOT be simply screwed off. I've personally seen enough examples of this lens with drilled holes and I also destroyed the front from one example because I was adamant on unscrewing the front. It's actually fixed to the body and can only be accessed from the rear of the lens.

The dots you see are simply condensation spots. It'll take you a minute or two to actually get those removed. I usually breathe on the element and wipe with a clean glasses cloth (microfibre). If you need chemicals, pure methanol is perfect and won't leave streaks. Wipe with a wet (methanol) lens cloth, clean off with a dry lens cloth.

To those mentioning balsam separation - the rear of the lens has the cemented group and can often separate. This barely impacts IQ unless the separation progresses deeper into the element group.

Source: Loads of K and A 50/1.2 lenses.
Thank you, very good information from personal experience.
01-06-2020, 11:14 AM   #11
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Neither fungus or separation. Very good chance it can be cleaned if you can get to it. It may not be affecting things as much as you think though -- lack of contrast and glowy pretty much describes the f1.2 look if you are shooting wide-open. If it is still like that at f/5.6 or f/8 (where is should be wickedly sharp with good contrast) then maybe it is causing a big degradation, but I doubt it is. So clean it if you can, but don't expect a big difference optically.
01-06-2020, 11:46 AM   #12
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My first thought was something called Schneideritis,* a condition often associated with lenses from that maker. It presents as a spread of white dots (often more prominent towards the edges) and is caused by separation of the black paint applied to the lens edge bevels. That said, it may be something else, including condensation dots. I don't think it is fungus or separation.


Steve

* Use Google image search for example photos.

Last edited by stevebrot; 01-06-2020 at 12:17 PM.
01-06-2020, 11:49 AM   #13
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QuoteOriginally posted by vonBaloney Quote
It may not be affecting things as much as you think though -- lack of contrast and glowy pretty much describes the f1.2 look if you are shooting wide-open. If it is still like that at f/5.6 or f/8 (where is should be wickedly sharp with good contrast)
Even getting that lens up to f/2 and it is getting really sharp or at least that is what I've found with my A version and by 2.8 it is golden. However even at those stops you are still at fairly narrow depth of field so that may account for some of the perceived softness. The softness and glowy effect wide open is fun, I just need to figure out how to make it work.
01-06-2020, 11:52 AM   #14
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QuoteOriginally posted by vonBaloney Quote
Neither fungus or separation. Very good chance it can be cleaned if you can get to it. It may not be affecting things as much as you think though -- lack of contrast and glowy pretty much describes the f1.2 look if you are shooting wide-open. If it is still like that at f/5.6 or f/8 (where is should be wickedly sharp with good contrast) then maybe it is causing a big degradation, but I doubt it is. So clean it if you can, but don't expect a big difference optically.
Yeah, I tried stopping it down and that's when I knew something was up with it - ugly all the way through. I can post some sample shots later if anyone is interested. Or you can duplicate the look it by smearing butter on your lens
01-06-2020, 12:18 PM   #15
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QuoteOriginally posted by stevebrot Quote
My first thought was something called Schneideritis,* a condition often associated with lenses from that maker. It presents as spread of white dots (often more prominent towards the edges) and is caused by separation of the black paint applied to the lens edge bevels. That said, it may be something else, including condensation dots. I don't think it is fungus or separation.
Don't think I've ever seen a Pentax lens with Schneideritis, and it looks too centralized for that, but those effects can be very weird so it isn't impossible I guess. Interestingly enough, none of the lenses I've had that did have Schneideritis have been Schneiders. (Mayima/Sekors are the ones I've had trouble with -- my Schneider lenses have all been fantastic lenses. )
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