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07-10-2020, 12:53 PM   #1
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P67 Lens Restoration After Hot Car Incident?

Hello, Iím a longtime reader of Pentax Forums and gear reviews and this is the first issue Iíve had that wasnít solved by searching through old threads:

It couldíve been avoided so easily, but the camera bag was left for about four hours in the back seat of the car in the middle of the Texas summer. By the time it was retrieved, all the contents were pretty warm to the touch. Looks like the P67 lenses (90/2.8 & 200/4 SMCP, 75/4.5 Tak, 45/4 SMCP6x7) all picked up a little bit of internal haze to some degree, Iím assuming from evaporated lubricants.

The 45/4 already had some haze behind the rear element. Now that haze is thicker and there are additional accumulations deeper down in the elements around the aperture. Hereís a picture showing the haze behind the front element : https://i.imgur.com/ZJiVZpV.jpg

The 45 got it the worst. Iím hoping that itís not significant for the others, but I wonder if Iím going to need to either get the 45 cleaned or replace it. Too bad itís the most complex lens design of the four, making it the hardest to clean. I think it even has a floating element.

Does anyone know of a mail-order service that does cleaning of old lenses like these? I suppose I need to get a quote and decide if itís going to cost more to get the service than it is to buy a replacement. Good cosmetic condition 45ís seem to be going for north of $300 these days, and in my experience cosmetic condition doesnít always track to lens optical quality (factory defects, centering problems, etc are alway still possible).

The 200/4 was mint perfect before being left in the heat. Now it has two streaks of haze behind the front element. The 90/2.8 also now has some behind the front element as well, and deeper in, but itís pretty thin...need a pen light at just the right angle to see. Iím hoping there wonít be much image quality degradation with either of those. There were in such nice condition before, though! I wonder how hard it would be to access the rear of the front element on the 200. It seems like it might be easy to open up.

Hopefully this post is an effective reminder to all who read it. Do not leave your lenses in a hot car, especially outside of the trunk. Youíll end up with haze on your elements at best, and degraded coatings or separating cemented elements are a real possibility.

07-10-2020, 01:43 PM   #2
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QuoteOriginally posted by A Prism Cont. Quote
Hello, Iím a longtime reader of Pentax Forums and gear reviews and this is the first issue Iíve had that wasnít solved by searching through old threads:

It couldíve been avoided so easily, but the camera bag was left for about four hours in the back seat of the car in the middle of the Texas summer. By the time it was retrieved, all the contents were pretty warm to the touch. Looks like the P67 lenses (90/2.8 & 200/4 SMCP, 75/4.5 Tak, 45/4 SMCP6x7) all picked up a little bit of internal haze to some degree, Iím assuming from evaporated lubricants.

The 45/4 already had some haze behind the rear element. Now that haze is thicker and there are additional accumulations deeper down in the elements around the aperture. Hereís a picture showing the haze behind the front element : https://i.imgur.com/ZJiVZpV.jpg

The 45 got it the worst. Iím hoping that itís not significant for the others, but I wonder if Iím going to need to either get the 45 cleaned or replace it. Too bad itís the most complex lens design of the four, making it the hardest to clean. I think it even has a floating element.

Does anyone know of a mail-order service that does cleaning of old lenses like these? I suppose I need to get a quote and decide if itís going to cost more to get the service than it is to buy a replacement. Good cosmetic condition 45ís seem to be going for north of $300 these days, and in my experience cosmetic condition doesnít always track to lens optical quality (factory defects, centering problems, etc are alway still possible).

The 200/4 was mint perfect before being left in the heat. Now it has two streaks of haze behind the front element. The 90/2.8 also now has some behind the front element as well, and deeper in, but itís pretty thin...need a pen light at just the right angle to see. Iím hoping there wonít be much image quality degradation with either of those. There were in such nice condition before, though! I wonder how hard it would be to access the rear of the front element on the 200. It seems like it might be easy to open up.

Hopefully this post is an effective reminder to all who read it. Do not leave your lenses in a hot car, especially outside of the trunk. Youíll end up with haze on your elements at best, and degraded coatings or separating cemented elements are a real possibility.
May want to contact these guys!
How To Clean Your Camera Lenses
07-10-2020, 06:14 PM   #3
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QuoteOriginally posted by A Prism Cont. Quote
Hopefully this post is an effective reminder to all who read it. Do not leave your lenses in a hot car, especially outside of the trunk.
I thought the photo showed an examine of condensation. My first thought was that the whole kit and caboodle should be placed into a dry box with silica gel and left to sit for a week, then removed. If it is indeed haze from internal lubricants/cement, disassembly at a service facility e.g. Eric at pentaxs.com, would be wise. You're correct about the possible cost of service exceeding the value of equipment. The camera should also be checked over, especially the adhesive holding the reflex mirror and the patency of the every-so-tiny cover and back seals, additional to the prism seals: all of these can virtually liquify in sustained hot conditions.


Regarding the 45mm f4 (yes, it has a floating element), there is some small noted variation in optical performance among this lens; some users report marked softening at the corners, others over-frame softening and others still nothing reported at all (me). It is one of only scant few with a gelatin filter clasp at the rear element, so it can be a useful lens in some uncommon circumstances. It is, for the most part, a very sharp lens and a companion to the 55mm f4. The 45mm f4 is my standard lens for landscape, only booted off to make way for either the 90/2.8 or 75/2.8AL.
07-10-2020, 06:15 PM   #4
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Thanks. Used these folks before?

Itís funny, there are two other places called ĎPrecision Cameraí that I know of, and at least one of them (Precision Camera here in TX) doesnít do lens disassembly jobs.

07-10-2020, 06:43 PM   #5
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Here you have a 'complete' list:
Pentax Repair Facilities (Wordwide listing) - PentaxForums.com
Precision has been good for some people and a nightmare for others. I have no experience with them.
07-10-2020, 07:14 PM   #6
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QuoteOriginally posted by Silent Street Quote
I thought the photo showed an examine of condensation. My first thought was that the whole kit and caboodle should be placed into a dry box with silica gel and left to sit for a week, then removed. If it is indeed haze from internal lubricants/cement, disassembly at a service facility e.g. Eric at pentaxs.com, would be wise. You're correct about the possible cost of service exceeding the value of equipment. The camera should also be checked over, especially the adhesive holding the reflex mirror and the patency of the every-so-tiny cover and back seals, additional to the prism seals: all of these can virtually liquify in sustained hot conditions.


Regarding the 45mm f4 (yes, it has a floating element), there is some small noted variation in optical performance among this lens; some users report marked softening at the corners, others over-frame softening and others still nothing reported at all (me). It is one of only scant few with a gelatin filter clasp at the rear element, so it can be a useful lens in some uncommon circumstances. It is, for the most part, a very sharp lens and a companion to the 55mm f4. The 45mm f4 is my standard lens for landscape, only booted off to make way for either the 90/2.8 or 75/2.8AL.
This photo was taken about a week after the incident, so unfortunately for me itís probably not condensation, although Iíll try a desiccant packet in a ziploc cause it sure wouldnít hurt.

Iíve... wondered about the idea of letting it get hot again, taking off the rear plate and ... going at it with a powerful vacuum. If the haze got moved onto the glass through vaporization, maybe it can be reduced somewhat in the same way. But I feel like Iíd have to accept that the lens is trash first before attempting such a harebrained corse of action.

In seriousness, maybe Iíll ask Eric at Pentaxes about his cleaning it first before going to the big guys at Precision. Although as much as his name comes up around here and elsewhere I think he must be a very busy person.

And yes, this stings most because this 45 was as close to perfect as any manual focus super-wide lens Iíve ever owned. Itís fantastically even in its rendition from edge to edge; something Iíve found *so many* Nikon, Minolta, and even Zeiss wide primes to lack, in that theyíll have a Ďsoft sideĎ and a Ďsharp sideí.

Come to think of it, all the P67 lenses Iíve had enjoyed solid centering and thus very even center-to-edge sharpness rolloff on all sides. But that in no way means that Iíd trust the next P67 45 I buy to be well-centered. Hence my attachment to the one Iíve got.
07-11-2020, 05:47 AM   #7
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QuoteOriginally posted by A Prism Cont. Quote
Thanks. Used these folks before?



Itís funny, there are two other places called ĎPrecision Cameraí that I know of, and at least one of them (Precision Camera here in TX) doesnít do lens disassembly jobs.

Precision Camera is Austin is a (very good) retail store. Itís unrelated to Precision Camera that does factory servicing.

But I would always check with Eric Hendrickson first.

Rick ďwho bought an old Sinar P Expert Kit at PC in Austin two years agoĒ Denney
07-11-2020, 10:39 AM   #8
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In historical times (for me), condensation in a lens assembly was treated by placing the assembly in a vacuum jar, pumping it down towards vacuum, waiting a while, then back-filling with dry nitrogen. This assumes that whatever seals are in use are as leaky in the process as they were when the condensation occurred. A lens assembly with some parts well sealed might not want to be anywhere near vacuum, but should be able to handle a psi or so of reduced pressure to allow the unsealed parts to dry out. Several pumpings and dry nitrogen fill cycles may be needed if using very modest vacuum pressures. All our lenses should be able to take aircraft cabin pressures.

The only way I can think of for a hot car to introduce humidity into a lens assembly is to do so on the cooling phase when the pressure inside the lens assembly will fall and be replaced by outside air. Hence, the original idea of grease deposition seemed logical.

07-11-2020, 05:31 PM   #9
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Hi,

I am sitting here thinking that the heat may have affected the cement used to group the elements.

Stan
07-12-2020, 08:19 AM   #10
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QuoteOriginally posted by wa2kqy Quote
Hi,

I am sitting here thinking that the heat may have affected the cement used to group the elements.

Stan
I assume you mean the cement between lenses of equal curvature bonded together. Such cements should, even over the past 50 years, be of the index matching type (index of refraction equal to the square root of the product of the two indices of refraction being cemented) and not mere balsam. In the US, a large part of the customer base would be MIL, and so such cements would have to meet MIL temperature specs. In any case commercial purposes such as rifle scopes would be expected to have to endure car interior temperatures.

Perhaps early 6 x7 lenses were more primitively cemented, and your conjecture is on the mark. I would expect separation to show up not as haze, however, but as stronger Boys points reflections when looking near to the sun. Interference bands might also appear.

Barrel grease could have a volatile component and be the guilty party, but I suspect that would be a long-term issue.

I'm going to bet my donut on moisture. Edit: Reviewing you photo, I have to ask: Was this incident in a wet part of Texas, or in a dry part?

Also worth considering is that automobiles out-gas a lot of stuff, in particular vinyl chloride, that could find their way into a lens if heated and then cooled. So might a camera bag, or some other material in or about the camera bag.

Last edited by kaseki; 07-12-2020 at 12:12 PM. Reason: added conjecture
07-12-2020, 11:58 AM   #11
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You might try KEH in Atlanta
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