How to prevent fogging up of lens

[arnica]

Hi all,

Does anyone know how to prevent the lens fogging up in the evening/cold environments? I took a few time lapses last year, however i had to abandon it due to dew forming on the lens and blocking the frame.

Any hints or tips you can throw this way? With Winter fast approaching, these might come in handy also.

[mortalitas]

it is suggest to use hand warmers. i have no idea where to buy them, but a quick search on google should uncover something.

sorry i couldnt be more help

[Starvin Marvin]

You can purchase a purpose built lens warmer but to my mind, the cost doesn't justify it. A couple of hand warmers should do fine, just use and elastic band to secure it to the barrel. Another tip for nights is use a cover on your camera (particularly if it is not weather sealed) otherwise you can get a nice layer of dew on your gear!

[ShutterandBrew]

This might sound a bit strange but if there is air movement over the lens it helps a lot, Years ago I had one of those little hand held battery fans and it was just enough to blow some air across the face of the lens to stop the condensation. Might help??

[nardes]

You need to maintain the lens temperature just a degree or so above the ambient air temp to prevent dew from forming on the optics. A lens hood will slow down the formation of dew although these become less effective the shorter they are on e.g. wide lenses.

Astronomers use electrically powered “dew heaters” which are basically low power heating elements that wrap around the optics to keep their temperature just above the ambient air. These require power, either mains/mains adapter or a 12VDC battery.

If the air is very dry then you may not require a dew heater, but here in SE Qld they are almost a mandatory requirement.

BinTel sells the dew controller and the dew straps.

http://www.bintel.com.au/Accessories/Dew-Control/45/categorylist.aspx

Cheers

Dennis