[rob_k20d]

Recently, I took my camera (K-S2) out, with the 18-50 WR lens. It was pretty cold - snowing.

In these conditions, I had a problem - a small circle of condensation in the centre of the lens. On the inside. Presumably this means that there is water on the inside.

If it was a different lens, I might think it might have been my fault for not keeping the lens dry. But this lens is WR.

I know WR isn't waterproof, but it hasn't been submerged, or anything like that. Just the usual rain and snow. (And not torrential rain as far as I remember.)

Anyway, my question is, am I right in thinking that I shouldn't have this problem, and that I should be able to take it back to the shop for a refund. It should still be under warranty I think.

Any thoughts?

Thanks

[jatrax]

Condensation due to temperature change. Really has nothing to do with the WR.

It works like this: take your lens and put it in a warm moist environment, like your house. Then go outside into a cold, moist environment. The warm air in the lens has lots of humidity in it, but as the lens cools the air cools and cannot keep all that humidity so it condenses out.

The reverse can cause issues as well: If your lens is very cold and you take it inside to a warm, moist environment you will also get condensation.

[Oldbayrunner]

When going from one extreme to another it is best to keep your lens and camera inside a plastic baggie. Then let the items adjust to the shooting temperature, usually 20-30 minutes is suggested.

[Jens Lyn IV]

Also note that the DA 18-50 is subject to the piston effect; every time you collapse/extend, zoom, or change focus, the internal volume changes, causing the lense to breathe, thus drawing in outside air and, possibly, water.

[rob_k20d]

I have to say, I was quite surprised by these replies. I figured that if condensation inside is caused by there being moisture inside the lens, and if WR is supposed to keep moisture out of the lens, WR looks relevant.

Also, people seem to suggest that WR (and the limitations of WR in keeping water out) were relevant in this case: https://www.pentaxforums.com/forums/6-pentax-dslr-discussion/96738-pentax-k-7...densation.html

Also, as well as my K-S2, I also had my Q7 with me - at the same time, in the same conditions. The Q7 doesn't have a WR lens, yet it did not have condensation inside the lens.

Anyway, despite being discouraged by the comments above, I thought it was worth taking it back to the shop to see what they would say.

Given the comments above, I was expecting the worst. But I didn't even have to argue. Straight away, they wanted to know which lens I had got with the camera - was it WR. And as soon as I said it was, they just said, you shouldn't have moisture inside with a WR lens, so you shouldn't be getting condensation, so we'll send it back under the warranty.

Of course, I haven't heard what Pentax will say when they get the lens, but it is promising.

So for anyone who comes to this forum because they have a similar problem, I would suggest that it is worth taking the lens back to the shop to see if they will repair it under warranty.

[pete-tarmigan]

I have to say, I was quite surprised by these replies. I figured that if condensation inside is caused by there being moisture inside the lens, and if WR is supposed to keep moisture out of the lens, WR looks relevant.

WR lenses cannot be purged with nitrogen to force normal atmospheric air out of them, as some expensive, weather-sealed binoculars and spotting scopes are to prevent internal fogging. This is because WR lens's zoom mechanisms are external, i.e., the volume of air inside the lens increases as you zoom to higher focal lengths (increasing the length of the lens) or focus, drawing external air into the lens. The weather seals prevent rain from coming in, but they can't block the air or the lens wouldn't be able to zoom or focus.

When air cools, its capacity to hold humidity reduces. Therefore, if your lens is at 21º C (room temperature) and a safe relative humidity (50%), then you take it outside to -5º C, some moisture will be forced out of the air that is inside lens. This moisture will condense on the surfaces of the lens. This is not the fault of the lens, because the air inside the lens was initially at a safe relative humidity. By keeping the gear inside a bag, slower temperature drop will allow air exchange to equalize the difference in temperature and relative humidity between the lens and the outside before the moisture condenses.

AW lenses (DA* and DFA* series) have internal zoom and focus mechanisms, i.e., the overall length (and therefore internal volume) doesn't change during zooming or focussing, but I don't know if they take in and expel any air during zooming and focusing. However, I'm pretty sure they aren't nitrogen purged.

[vonBaloney]

It is actually quite likely that WR lenses are more prone to condensation since they can't adjust as quickly (when mounted), especially in tropical environments. (In hot humid climates, going from dry cool air conditioning to hot humid outside is even worse than typical winter outdoor/indoor differences.) As noted above, anything that isn't completely and permanently sealed has normal air in it, and therefore can condense. But most of the time if you do get condensation, it will go away will no lingering effect, but once in a while it will leave a circle on an element so best to avoid it if you can. If you do see it (and running to the store to return it is not an option), then quickly put the lens in a drying environment (dry cabinet, bag of rice, etc) and it will probably be fine. Also, if you buy a lens via internet in the winter (or a camera or anything else you don't want moisture on for that matter) and it has been sitting around on a cold delivery truck, don't open the box for a few hours until it has warmed up in your house.)

Short answer: WR will not prevent condensation, and may well make it more likely (again, when mounted).

[drypenn]

Well, if a lens is perfectly and completely sealed, even from the ambient air (which contains moisture), it will be almost physically impossible to zoom, or focus the lens.

[discharged]

What will a plastic bag help you with? Nothing on its own... You ned all the info to do it correctly and you need the right kind of air in the plastic bag. If it is hot You want heated inside air and when it is cold you want heated outside air. This way you will have a low relative humidity in the air inside the bag and the humid air in the camera house and the lens will be mixed with the other air giving you low relative humidity

[vonBaloney]

What will a plastic bag help you with? Nothing on its own... You ned all the info to do it correctly and you need the right kind of air in the plastic bag. If it is hot You want heated inside air and when it is cold you want heated outside air. This way you will have a low relative humidity in the air inside the bag and the humid air in the camera house and the lens will be mixed with the other air giving you low relative humidity

You want to seal the bag (with the camera/lens in it) before changing environments, and then once in the new environment don't open it again until the temperature has equalized, i.e. "a little while".

[drypenn]

What will a plastic bag help you with? Nothing on its own... You ned all the info to do it correctly and you need the right kind of air in the plastic bag. If it is hot You want heated inside air and when it is cold you want heated outside air. This way you will have a low relative humidity in the air inside the bag and the humid air in the camera house and the lens will be mixed with the other air giving you low relative humidity

Air is a poor heat conductor. A lens inside a bag filled with ambient air, when taken to a different temperature will allow the lens to slowly acclimatize preventing or keeping condensation to a minimum.

[discharged]

You want to seal the bag (with the camera/lens in it) before changing environments, and then once in the new environment don't open it again until the temperature has equalized, i.e. "a little while".

Air is a poor heat conductor. A lens inside a bag filled with ambient air, when taken to a different temperature will allow the lens to slowly acclimatize preventing or keeping condensation to a minimum.

no, the relative humidity in both cases could still be 100% and the water would need to condense on something, either the inside of the bag or the camera itself. the only way to prevent condensation is to make sure you never reach a 100% relative humidity and that there is some kind of harmony between air and camera temperature inside the bag.

[vonBaloney]

no, the relative humidity in both cases could still be 100% and the water would need to condense on something, either the inside of the bag or the camera itself. the only way to prevent condensation is to make sure you never reach a 100% relative humidity and that there is some kind of harmony between air and camera temperature inside the bag.

Have you actually tried it and it failed you?

It is more about the time, not the air -- how are you going to get the "correct air" in any practical way? The bag slows the transition of the temperature change of the air in the camera/lens because it is not being exchanged suddenly with the "new air" but has to conduct through the surface of the bag. And so if it condenses, it won't be much (on the inside of the bag, it might on the outside). And then when the temperatures are equalized it should be ok because there is no temperature shift when it fully is exposed to the new environment. Of course if you are going out in the tropics there will just be a ton of moisture the air which can be problematic. In practice I'd also have an soft absorbent cloth wrapped around the camera/lens and maybe some desiccants to absorb any moisture that did occur. But as long as you can prevent a *rapid* transition, then internal fogging is unlikely. (And again, even if it does then it is not usually the end of the world -- put it in a dry environment quickly and most of the time that will clear with no lingering problem.)

[BigMackCam]

When going from one extreme to another it is best to keep your lens and camera inside a plastic baggie. Then let the items adjust to the shooting temperature, usually 20-30 minutes is suggested.

You know, I'd have thought a plastic bag would be a bad idea... You'd potentially get condensation inside that too, wouldn't you?

If I'm going from one temperature extreme to another, I leave my gear in a padded camera bag and let the temperature slowly equalise. I do the same with international parcels now, too, as any that have come by air freight are often freezing cold. Now I open the main cardboard box and leave the parcel to stand in a warm room of the house for a couple of hours, by which time the temperature difference isn't so extreme.

[drypenn]

no, the relative humidity in both cases could still be 100% and the water would need to condense on something, either the inside of the bag or the camera itself. the only way to prevent condensation is to make sure you never reach a 100% relative humidity and that there is some kind of harmony between air and camera temperature inside the bag.

I live in a tropical country where outside humidity can reach up to 80% during summer, and temperature can reach up to 39 degrees centigrade. Indoors, my home is set at 23 degrees centigrade with controlled humidity of 40%.

The solution I have been proposing has been tested repeatedly over and over and over and over and over and over and over again. If you don't want to believe, fine.