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01-21-2011, 02:53 PM   #16
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QuoteQuote:
there is no evidence that I see of any failed WR
.

Did you read the first post in this thread?

01-21-2011, 03:52 PM   #17
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I live in the tropics where humidity is high. It is almost a given that if fungus is to be avoided, one has to keep lenses in an electric dry box which keeps the relative humidity low (about 40% RH). And it doesn't matter one bit if a lens is weather sealed or not. If a lens has been exposed to moisture, then wipe it dry before storing them. Just keeping a lens in a camera bag (which can absorb moisture and exposed to fungal spores) is no insurance that fungus won't show up, even if you use it everyday. Now if the fungus is on the exterior surface, just clean off with a little isopropyl alcohol or eclipse lens solution. If it is on the inside, then either live with it and rue your misfortune for not keeping your lenses properly or get it cleaned professionally.

Bottomline is WR has no bearing on whether a lens is susceptible to fungus or not. WR merely relates to a lens' resistance to water ingress. All lenses can get fungus and mold under the right conditions.
01-21-2011, 04:57 PM   #18
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QuoteOriginally posted by normhead Quote
.

Did you read the first post in this thread?
I did. did you read any of my posts before making your comment? where is the evidence that the fungus is due to compromised WR o-rings?
01-22-2011, 06:16 PM   #19
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i'm guessing disassembly is not an option for me then! I'll try the UV light first. If that fails, i'll just have to take more photos using this lens before it dies

thanks for the replies, everyone!

01-23-2011, 07:39 AM   #20
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QuoteOriginally posted by miks Quote
i'm guessing disassembly is not an option for me then! I'll try the UV light first. If that fails, i'll just have to take more photos using this lens before it dies

thanks for the replies, everyone!
the UV light may kill the fungus, but it wont make the growth you see disappear. how that might affect IQ is anyones guess, but I would suggest seeking out a Pentax certified repair center to have it disassembled and cleaned properly. if the lens is worth that much to you of course.
01-23-2011, 07:57 AM   #21
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QuoteQuote:
where is the evidence that the fungus is due to compromised WR o-rings?
Argument from ignorance, also known as argumentum ad ignorantiam or appeal to ignorance, is an informal logical fallacy. It asserts that a proposition is necessarily true because it has not been proven false (or vice versa). This represents a type of false dichotomy in that it excludes a third option, which is: there is insufficient investigation and therefore insufficient information to "prove" the proposition to be either true or false. Nor does it allow the admission that the choices may in fact not be two (true or false), but may be as many as four; with (3) being unknown between true or false; and (4) being unknowable (among the first three). And finally, any action taken, based upon such a pseudo "proof" is fallaciously valid, that is, it is being asserted to be valid based upon a fallacy.[1] In debates, appeals to ignorance are sometimes used to shift the burden of proof.

From Wikipedia

QuoteQuote:
"Took my da 50-200 to a 3 day trip with continuous light rain and strong winds. While doing my complete cleaning when I got home, I saw fungus growth on the front element.
from Pentax

QuoteQuote:
Simplified weather-resistant construction

This zoom lens features a simplified weather-resistant construction to prevent the intrusion of water and moisture. By mounting it on a weather-resistant PENTAX digital SLR camera body, the user is assured of a durable, dependable digital imaging system that performs superbly, even in the rain and mist, as well as at locations prone to the spray of water.
Are you saying there is a possibility that the mold in this lens grew without moisture, or that the moisture was already in the lens, or that the lens was damaged? What exactly are you saying? There is certainly evidence that under sustained conditions water penetrated the seals in this lens, just not conclusive evidence. Yes there are other possibilities. But the most likely possibility in my opinion, is that the WR is not completely dependable and precautions should still be taken to keep your lenses dry. Lack of evidence doesn't prove anything. One way or the other. Show me the research you (or anyone) has conducted in to the dependability of the seals. (That would be evidence.) I'm guessing most people are like me. Even though the seals should be good, they do their best to just keep their lenses dry. A lack of evidence of leakage should be expected. Anecdotal evidence would seem to support both arguments.

It's your choice, do what you want. If I think differently, why is that so important to you that you need to make a federal case out of it? People who think what I think aren't going to suffer in any way. Those who put absolute faith in the Pentax Water seals, are at risk. As I said, there are two legal terms.. Waterproof.. and that comes with a depth rating.. and Water Resistant. Water Resistance isn't worth much. It's a statement that efforts have been made to make the lens waterproof. No where are there claims as to how effective those efforts might be, what the expected failure rate might be in various conditions, or advice on what situations should or shouldn't be avoided.

We're working with very little information. My advice is take that in to consideration. Not all the feedback is positive.
01-23-2011, 08:49 AM   #22
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If you brighten up the image a bit I do see what blende8 poster said about a there being an anomaly at the point where the fungus growth started.
Manufacturing defect or possible damage that affected the weather resistant properties perhaps?
01-23-2011, 10:47 AM   #23
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QuoteOriginally posted by normhead Quote
There is certainly evidence that under sustained conditions water penetrated the seals in this lens...
No, there's not.

Weather seals or not, ALL zoom lenses have to allow air to enter and exit the body as the zoom extends and contracts. There is no way for a zoom lens to extend without sucking in air to fill the expanding inner space. This is the entry point for moisture, i.e. water vapor, which provides the conditions necessary for mold growth. So it does NOT logically follow that the presence of mold indicates weather-seal failure.

01-23-2011, 11:06 AM   #24
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QuoteQuote:
So it does NOT logically follow that the presence of mold indicates weather-seal failure.
But it could follow that the moisture came in through the seals. The conditions were right for it. Extended exposure difficult conditions etc., That's where your argument falls apart. You need more research to determine what the cause of the mold is, until then there is no "logically". There's at least 4 points been made, water through the seals, moisture coming from the camera body, moisture from moisture sucked in from air, focusing or extending the zoom., moisture introduced during manufacture. If the thread goes on long enough, we'll probably have a few more. Until there's some indication based on further research, I'd say, logically schmogically. (Pronounce that mudder fokkers ). If moisture gets sucked in because of humid air getting sucked in while focusing.. that's even more reason to stay out of bad weather with this lens. Rain is the result of supersaturated air (or 100% humidity.) If that were true it would be just as smart keeping the camera out of fog or rain as if droplets were migrating through the seal. To be fair, I think based on where the mold is, the most logical is supersaturated air getting sucked in to the lens and then condensing in the inside of the exterior glass after a temperature drop. The outside glass got cold first, so it got the condensation. I've seen similar with my water resistant GPS. Temperature drops, GPS window fogs. Water seals hold the moisture in.

Logically (schmogically), you shouldn't get a lens wet. Did I mention a pelican case will prevent circulation of humid air around the camera? Anyone who has used water proof packs, waterproof tents, waterproof rain-gear, waterproof anything knows that there are conditions where water gets in, to everything. You can go on all you want about Pentax WR lenses being waterproof, to which I say pfffft. Give me one of yours and I'll show you the difference between waterproof and water resistant. I won't be finding out with one of mine, but, do what you like.

Last edited by normhead; 01-23-2011 at 11:18 AM.
01-23-2011, 11:37 AM   #25
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QuoteOriginally posted by normhead Quote
Logically (schmogically),
Look, you were the one who started talking about logic.
QuoteOriginally posted by normhead Quote
That's where your argument falls apart.
I don't think I'm making an argument?
QuoteOriginally posted by normhead Quote
You can go on all you want about Pentax WR lenses being waterproof, to which I say pfffft. Give me one of yours and I'll show you the difference between waterproof and water resistant. I won't be finding out with one of mine, but, do what you like.
Huh? My only point was that YOUR conclusion
QuoteOriginally posted by normhead Quote
There is certainly evidence that under sustained conditions water penetrated the seals in this lens
has no basis in fact. It was ME who pointed out that moisture can enter the lens with the zoom function, no matter what the condition of the seals. I never said the WR lenses are water-proof, not even close. No one in this thread has.
01-23-2011, 01:46 PM   #26
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I'm sticking with my original and only point. Take your WR lenses out in bad weather at your peril, and take whatever precautions you can to protect them from moisture of any sort. Gasseous or in liquid or solid form.

That's my only point. Facts schmacts.
01-23-2011, 02:38 PM   #27
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QuoteOriginally posted by séamuis Quote
the UV light may kill the fungus, but it wont make the growth you see disappear. how that might affect IQ is anyones guess, but I would suggest seeking out a Pentax certified repair center to have it disassembled and cleaned properly. if the lens is worth that much to you of course.
No, but when dead, the fungus often becomes much paler and harder to see. From the original picture, in my opinion and experience, that bit of fungus will have very little, if any, impact on IQ.
01-23-2011, 02:48 PM   #28
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Dudes...

I read the first several comments and scanned the rest and did not see anyone pointing out the obvious...
You don't need to have a leak to have high humidity inside the lens
Change the lens once in a high humidity environment and the mirror box and lens internals will be filled with humid outside air. Put the lens back on and you will have (as noted above) a nice greenhouse perfectly suited to microbial growth. This is true even if the lens and body were hermetically sealed and tested to 10 atmospheres. In fact, less than perfect seals might actually be an advantage in allowing humid air to more easily escape when in a less humid environment.

As also noted above, the battle against lens fungus in the tropics is an ongoing concern. Fungus is one of the risks of facing optical devices in those parts of the world. I remember many years ago visiting a marine research facility in the Caribbean and noting that they had a half dozen beautiful Wild microscopes I asked whether I might use one during my visit. The disappointing answer was that the optics on all of them were contaminated by fungus and that they were unusable as a result. Truly tragic considering both the cost and quality of those scopes.


Steve

(BTW...you don't have to have a leak to get visible droplets inside a lens either...humid lens change indoors in winter followed by taking the camera outside into the snow...)

Last edited by stevebrot; 01-23-2011 at 03:05 PM.
01-23-2011, 03:59 PM   #29
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QuoteOriginally posted by stevebrot Quote
Dudes...

I read the first several comments and scanned the rest and did not see anyone pointing out the obvious...
You don't need to have a leak to have high humidity inside the lens
Change the lens once in a high humidity environment and the mirror box and lens internals will be filled with humid outside air. Put the lens back on and you will have (as noted above) a nice greenhouse perfectly suited to microbial growth. This is true even if the lens and body were hermetically sealed and tested to 10 atmospheres. In fact, less than perfect seals might actually be an advantage in allowing humid air to more easily escape when in a less humid environment.
taken from my first post in this thread:

"from what I understand of all this stuff, is that the weather sealing can be a friend and a worst enemy. see, when the lens is sealed it helps prevent moisture from gaining access into both the lens and the body, but should moisture get in, the sealing makes it extremely difficult for the moisture to dry out. there was a similar story to this one on the forums before in regards to fungus growth, and the consensus is, that fungus and mold etc, is everywhere. its likely already in your lenses to begin with unless your lenses were manufactured and assembled inside environmentally controlled clean rooms. without sealing its easier for things to dry out. and as we all now, this stuff doesn’t grow in dry environments, it needs moisture. if you are using the equipment in less than desirable conditions with weather sealing, but say you change lenses, well now you have allowed moisture to get in. then you attach another sealed lens on the body and it stays there. well now you have a pretty darn good growing environment. see what im getting at?"
01-23-2011, 06:53 PM   #30
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Although I am not 100% sure of the front element construction of the DA50-200mm but the front elements of a zoom lens are usually a group of two or more lens elements. Long story short is that area is sealed even before the sealing applied by Pentax, and from what I can see the lens should be darn near air-tight in that area. Moisture usually (not always; but this is a WR lens) gets deeper into the lens. With a new lens as this I say it was bad luck! A bad lens... something went wrong during construction.

You could open the lens by turning the retaining ring but it would do you no good. As I said the fungus is in a sealed area so you won't be able to clean it. Perhaps a call to CRIS Camera or your Pentax service center can give you your options.
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