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Old November 28, 2012, 12:14 PM   #1
Eppie
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Loss of clarity from storing their scopes in dark safes or closets?

Hi Everyone,
A few years ago I had a few camera lenses go blurry on me. A technician told me that it is a common occurence when people store lenses in a dark, humid place ( in my case it was my closet off the master bathroom). Apparently a type of mold grows on the lenses rendering them blurry, and it can't be cleaned because it etches into the lens.

He suggested that in the future I put my new lenses on a shelf and point them towards a window. The light would prevent the mold from growing.

My question is this: Has anyone here experienced a loss of clarity from storing their scopes in dark unventilated safes or closets?
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Old November 28, 2012, 12:18 PM   #2
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Won't say it ain't so but I've never seen nor heard of it.
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Old November 28, 2012, 12:38 PM   #3
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That sounds like what happened to an old camera of mine.
It was stored in a box for years and somehow the lens got scratched or etched.
There was no way anything came in direct contact with the lens, though.
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Old November 28, 2012, 12:48 PM   #4
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It's the multi-coating,,,

The multi-coating used on camera lenses (scope lenses?) is a gelatin substance.

Mold can and often does form on it,,,
You can clean it off but you will lose the anti-glare feature.

Nikon, Canon, and Minolta all used the same stuff,,,
This has been a known issue since the 80's.

Aarond

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Old November 28, 2012, 12:57 PM   #5
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I can see humidity causing a probem, but as long as the temperature and humidiy are controlled I can't see storing in the dark as a problem
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Old November 28, 2012, 01:24 PM   #6
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Back in the pre-digital days I developed my own photos .I had problems with the enlarger lens fogging . It turned out to be that the lens was stored in a styrofoam case .The styrofoam outgased causing the problem. I had a car notorious for windows fogging -from plasticizer inn the vinyl !!!
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Old November 28, 2012, 02:02 PM   #7
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http://www.amazon.com/Stack-On-SPAD-...ords=desiccant

Or other desiccant will keep "humid" out of the equation and probably keep this from happening.
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Old November 28, 2012, 04:47 PM   #8
wogpotter
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Quote:
The multi-coating used on camera lenses (scope lenses?) is a gelatin substance.
Since when may I ask?

I've been in the optics industy since the 1970's & never heard of any such thing.
There are coatings, & multi-layer coatings, but they are vacum deposited chemical & mineral deposits utterly devoid of anything remotely resembling "gelatin", or any other organic material.
http://en.wikipedia.org/wiki/Optical_coating

There are also "cements" used to bond together certain individual elements to produce a combination effect of high & low refractive index glasses & they were once something called "Canada Balsam" which is organic, but is emphatically not "gelatin".
http://en.wikipedia.org/wiki/Canada_balsam

More modern bonding & more advanced forms of optical glass have minimised this nowadays though.

Storing lenses in dark places will do absolutely nothing harmfull for ever, if just "dark" could harm lenses why aren't they destroyed by being stored on a camera with an opaque cap in place?

Now damp is harmfull to optics, fungus forms on the glass lens surface (coated or not it douesn't matter a bit), mites & micro-organisms can spread from rubbers & lubricants used elsewhere in the lens's mechanism & leave "cobweb" looking traces. Oils can migrate into areas where they shouldn't be forming "mirror pools" (gold colored patches & splotches), but absolutely none of this has anything whatever to do with fictional gelatin coatings which only exist as the emulsuion or backing of photographic film.

Quote:
Mold can and often does form on it,,,
You can clean it off but you will lose the anti-glare feature.
How do you clean off something that was never there in the first place?
You can accidentaly remove the bonded chemical layers with chemicals that wil attack the coating minerals, or just scrape it of abrasively by using incorrect, or grit impregnated cleaning materials. Only ever use the right materials & techniques & your lenses will remain coated, or multi-coated for aeons! Its not well known but optical glass is very, very soft & scratches easily. One side effec t of "Optical coating, or Multi-coating, or Super multi-coating" is anti-abrasion. The material is harder & more resistant to abrasion, but still softer than a grit-empragnated tissue, tie end, or shirt tail!

Coating does not primarily have an anti-glare function, it has some anti-glare as a secondary property, but its real purpose is to allow more light to pass through the optic's air/glass interface surface.

Quote:
Nikon, Canon, and Minolta all used the same stuff,,,
This has been a known issue since the 80's.
Actually Nikon (Nippon Kokaku K.K.) uses in house fabricated glasses & all proprietary coatings since the 1950's. (Nikkor glass works). They exclusively make & use thier own product, they do not sell outside if the Nikkor operation.
http://en.wikipedia.org/wiki/Nikon

Minolta also made (untill they closed & sold the rights to other companies) in house all its optical glass, blanks, elements & coatings, (Rokkor optical), but they do sell (or rather did sel untill they closed) to outside contractors, unlike Nikon who do not.
http://en.wikipedia.org/wiki/Minolta
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Old November 28, 2012, 05:27 PM   #9
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Quote:
He suggested that in the future I put my new lenses on a shelf and point them towards a window. The light would prevent the mold from growing.
I'm going to address this seperately from the above, just to keep it simple.
I wouldn't keep lenses "facing a window" especially if direct sunlight ever came in through that window. At several points inside a modern optical system, such as a zoom lens, the light is concentrated into something called a "circle of least confusion", you're probably familiar with the effect if not the name. Ever burn a leaf with a magnifying glass? As you moved the glass back & forth the image expanded, contracted & distorted to that one "sweet spot" wher the light's concentration ignited the leaf. That spot is a circle of least confusion & you can see the effects of long term exposure to direct sunlight!

Older (film) cameras frequently had obstructions, iris mechanisms, reflex mirrors & shutters inside that tended to block the effects. Unfortunately many modern digital cameras dont, all the light stops at full intensity at the CCD where the lens is focussed, again a hot spot just waiting to scorch.

In use cameras are usually mobile so the effect moves about before any serious damage is done, but there may wel be a warning about NOT storing the camera facing "bright lights" without the cover attached, this is why.

How to store well?
Simple few rules & you're GTG.
Dark is fine, but moisture is to be reduced, or eliminated with dryers, or ventillation.
If the lens just came in from oputside on a cold day it will form condensation of moisture, both inside & out. You can't wipe it away from the insides, just the outside, so wiping isnt a 100% answer. Just leave it out in the open till it equalizes for temperature & it will evaporate naturally causing no problems, after that put it back in its case or bag.

If it gets rained on do the same thing after wiping off all you can get at from the outside.

If the bag, or case gets wet empty it, open all the access you can & let it dry before putting any equipment back inside it.

Scopes, binoculars & so on can use the same techniques to keep them healthy for decades.
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Old November 28, 2012, 05:33 PM   #10
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I have a Flaigs 6mm with a Unertl 12x scope with the same issue,something on the inside of the objective lens. I talk to the person doing the repair and he mention fungus/mold or lens separation. Cleaned and adjusted and is clear in daylight but diminishes in lowlight. This scope is not hermetically sealed and filled with gas so moisture is a concern. deadeye


Sent it Parsons Scope Service in Ohio.

Last edited by deadeye1122; November 28, 2012 at 05:36 PM. Reason: add coment
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Old November 28, 2012, 05:40 PM   #11
30Cal
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I think your camera tech was thinking of the old Takumar (Pentax) lenses that yellow over time (something to do with the decay of Thorium in the glass or coating). Supposedly you stick them in the sun for a couple weeks and it'll clear up.
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Old November 29, 2012, 08:29 AM   #12
wogpotter
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With the right equipment, which is usually beyond the means of Joe Average, mold & fungus can be removed safely, but it is economically not feasable a lot of the time. Unfortunately mass production has lowered the price per unit so much that individual labor time has become prohibitive. Its actually cheaper to just buy a new one than fix the old one, unless it is in some way collectable.

Element seperation is a different story. The old dying Balsam has to be chemically dissolved (takes days or weeks to happen), the glass repolished (very risky, no-one will guarantee this type of work), & then recemented with fresh Canada Balsam (again weeks of curing time) & then reassembled & tested on an optical bench. Costs for this are astronomical.
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Old December 1, 2012, 07:47 PM   #13
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30Cal,

I really doubt it would be Thorium decay. Naturally occurring Thorium has a half life of 14 billion years. As far as I know, Thorium was never an additive to optical glass, although as a heavy metal I guess it could be used as a substitute for lead in "lead crystal" to some extent.

I'm a chemistry guy, but I never got around to solid state chemistry as far as how it interacts with crystallography. I'm sure someone on this forum knows what heavy metals are used in different brands of optical glass.

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Old December 1, 2012, 08:25 PM   #14
30Cal
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It's pretty well documented. They were using almost 30% by weight. Plus the purified thorium mixed into the glass goes through a long decay chain; most of the daughters have relatively short half-lives. So it actually gets worse with time.

http://www.orau.org/ptp/collection/c...cameralens.htm
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Old December 1, 2012, 11:04 PM   #15
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30Cal,

That is interesting, I looked up the decay chain to see if I could spot the daughter isotope that would be responsible for the browning.

Thorium-232 (14 billion years) alpha
Radium-228 (5.6 years) (most likely culprit) beta
Actinium-228* (6.1 hours) beta
Thorium-228 (1.9 years) beta
Radium-224 (3.7 days) alpha
Radon-220 (56 seconds) alpha
Polonium-216 (.15 seconds) alpha
Lead-212* (11 hours) beta
Bismuth-212* (61 minutes) alpha
Thallium-208* (3.1 minutes) beta
Lead-208 (stable)

Looking into the Radium, we find that discoloration of glass is common.
Quote:
When first prepared, nearly all radium compounds are white, but they discolor on standing because of intense radiation. Radiation causes a purple or brown coloration in glass on long contact with radium compounds. Eventually the glass crystallizes and becomes crazed.
What is happening is the Beta and Gamma radiation are knocking atoms around in the compound, and they are ending up in a more ordered state (crystallized) which is creating some sort of change in the index of refraction (as best I can tell).

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Old December 2, 2012, 09:34 AM   #16
wogpotter
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Thorium, or its relatives must be pretty much a Pentax/Takumar optics thing, most other companies in the photographic business use various forms of magnesium flouride-based coatings materials.
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