Effect of cold and heat on lens

[kristin.marvin]

When I took my zoom lens to Puerto Vallarta last summer, it developed a foggy spot from the humidity that took

weeks to clear. The last time I went out, it was cold, and again, fog on the lens. (Though, it wasn't nearly as

bad as the humidity.) The cold fog didn't seem to really affect my photos, but the humidity fog was AWFUL, and

there is the same unsharp spot in all my Puerto Vallarta pics with that lens (which, of course, I didn't notice

until I was at home and they were on my computer screen). I did some research on this and the only things I

could find were to "wait it out" and advise on putting the lenses in plastic bags before I come in from the cold

until they completely warm up (which I did). Is there any way to prevent, or minimize the fog that forms from

cold and humidity in the first place? I would assume spraying some kind of anti-fog on the lens front is a

terrible idea. Any suggestions would be most appreciated. Thanks!

[geoffs1]

I can't think of any way to prevent condensation when you take a cold object into a warmer, more humid environment. It's just physics...

 

http://en.wikipedia.org/wiki/Condensation

[lex_jenkins]

It's normal and unavoidable. Just the reality of sudden shifts in temperature and humidity.

 

Not much different from the problems faced by photographers of boxing and martial arts events (sweat, blood and worse flying), photojournalists in hostile crowds, or me photographing kids and animals - they all seem to want to mash their noses against my lenses.

 

When I expect it to be a problem I use a protective filter over the lens, which I can wipe quickly as needed. Eventually I replace the protective filters - they're good for up to a year or more depending on how frequently I need to wipe 'em. Even at $15-$50 (depending on brand and size) a UV, skylight or other protective filter is cheap insurance for a good lens in rough conditions.

 

Several years ago I photographed a springtime butterfly exhibit at a local botanic garden arboretum. Outside temperature was under 60F but dry; inside was 85F and dripping with humidity. Everything immediately fogged up. I'd already fitted my Olympus P&S digicam with a protective filter, so I could wipe it with my t-shirt and immediately take photos. I'd neglected to bring protective filters for my SLR lenses and forgot my lens tissues too. Not wanted to wipe my expensive macro lens with a t-shirt, I had to wait 30 minutes for the SLRs and lenses to adjust to the ambient temperature.

[kristin.marvin]

Lex, thanks for the tip. It never even occurred to me that a UV filter would take the brunt of the fogging. I am very new to this, obviously, and so I have yet to get any filters. I think this is a mistake, and that I should get some. So far, I have learned from reading that a UV filter will help with protecting the lens when dropped (which hopefully never happens, but, who knows) and now fog. And I'd rather replace a UV filter than an entire lens. Thanks so much.

[geoffs1]

<p>To be honest, I'm more worried about condensation <b>inside</b> the camera and lens, and less about the

exterior. Granted, the warm/humid air has less access to the insides but, except for weather sealing on the

highest-end cameras, a fair bit of air and moisture will get inside before the camera warms up.</p>

[craig_shearman1]

Are you talking about a foggy spot on the surface of the lens? You just wipe that off. I can't imagine it lasting more than a few minutes. Sounds more like you're talking about fog on an interior surface of the lens. That's a sign of poor seals on the lens, a problem that could happen with lower-cost consumer lenses but less likely with higher-cost profesional level lenses. Fog really should not be occuring inside a lens, at least not enough to last long. As for UV/skylight filters, I know others disagree but I put one on every lens the day it's bought. They only come off to change to other filters or be replaced. They protect against a whole host of things and, while others might disagree, do not perceptibly degrade the image quality.

[kristin.marvin]

Thanks for your responses. Yes, sadly I can not afford L series lenses :( and so my lens is more amateur quality, and that may be part of the problem. Luckily, the fog spot on the inside of my zoom lens cleared after a couple of weeks, so that's lucky. I wasn't sure if I could wipe off the fog from the exterior of the lens or if doing that would scratch it. I have seen the pro-UV and anti-UV filter debates, but I think I am going to be on the pro side for protection of the lens. :) Also need a polarizing filter for landscapes, but that's another topic entirely! :) Thanks for all of your responses.

[provo]

If you travel a lot and experience hot, cold and humid climates, it is always best to store your lenses in Ziploc bags with a sachet or two of silica gel. Then wait an hour or two for the lenses to adjust to the ambient temperature after coming out of the aircraft hold before you open the bag. This should prevent condensation or fogging. And the advice about filters, a lens is not complete without at least a UV filter. Good luck.