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06-11-2009, 06:02 PM   #1
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Lens fogging

I've bought a couple of second-hand lenses prior to my trip to Hong Kong -- a DA40 and a Sigma 10-20. Both seemed to be in very good condition.

Here in HK it's very humid, unsurprisingly. But I've found that the DA40 handles it beautifully, whereas the Sigma fogs up almost immediately, making it pretty much useless for outdoor use. Do I have a bad copy of the Sigma, or is this just one more example of superior Pentax workmanship?

06-11-2009, 06:14 PM   #2
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I have this problem with all lenses (including FA*s and Limiteds) when I enter swimming pool buildings in the winter so I doubt it is a workmanship problem. The problem occurs when the glass is colder than the humid air. There are two "solutions" that I know of:
- leave your equipment in the same environment that you intend to use it in; or,
- wait patiently for your equipment to acclimate.

06-11-2009, 06:45 PM   #3
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Solution 3.

zip lock plastic bags. Put the optic in a bag in the environment you have been in and the lens is acclimated to and seal the bag. Keep it in the bag until it reaches ambient temperature. The bag limtis how much moisture it has access to.
06-18-2009, 07:00 AM   #4
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Thanks, I appreciate the responses

Sure enough, I found that the lens cleared after half an hour or so.

06-18-2009, 10:01 AM   #5
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This could be a bit risky if it leaks, but . . .

Assuming you're leaving an airconditioned room for hot, humid conditions: fill a plastic water bottle with hot tap water and wrap it and the lens in a towel in preperation for going outdoors. The general idea is to pre-acclaimate your equipment to the temperature you're transitioning to.

Obviously, water bottles and cameras are not the best companions, but this works with reasonable precautions against accidents.

For long term use, fix up an insulated cooler with a low wattage light bulb if you're in an on-call situation where gear has to be ready on a moments notice. A soft-side (fabric) insulated cooler to keep your equipment in will minimize temperature change overnight and is easy to pack and carry as well.

06-19-2009, 04:51 AM   #6
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As it happens, I was staying in Kennedytown, which is a charming but rather seedy area. It was probably all for the best that I kept my fancy SLR tucked away in my bag while I was close to my hotel!

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