I brought my new 300mm out on her maiden voyage today, but as soon as I got out of my truck it fogged over. This is typical for where I live, its hot and humid down here, but my 70-200 usually is back to being clear before i get where I'm going. Not the case with the 300, it was 45 minutes before I could use the lens, I guess the large front element is holding its temperature for longer. It seemed to be perfectly fine after it cleared up, see the pictures below. Any advice would be much appreciated.
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Any Tips for Avoiding Condensation on a Big Lens?
- Thread starter skyler87
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areallygrumpyoldsod
Senior Member
The only answer is to leave it in the heat for 1 hour before use -- So you can either drive without AC in the cab, or if you can, keep it in a lockbox in the back.
Lcameron1951
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If you can store it safely away from AC at home ( locked garage overnight), it will help with condensation. I've also used a small hair dryer on the lowest setting in emergencies.
A lens heater is often used for astronomical telescopes to prevent condensation that comes from the scope cooling by radiation faster than the atmosphere around it and causing condensation for most of the night when the atmosphere is somewhat close to the dew point. Because they are often used all night, they usually use automotive batteries or power converters. However, they're typically 12v resistance heaters, so a small pack of 1.5v rechargables would do the job for a few minutes. About 5 minutes with the heater would probably be enough to get you working. They come with various sizes of velcro-attached heating element bands that go around the lens - order the size that fits yours.
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