Tips for preventing fogging in housing?

Just wondering what tips/steps you take in making sure your housing doesn't fog up. Do you keep the camera/housing in a cool place like a cooler before you go in the water? Do you put the silica pacs far in advance? Do you heat the housing in the sun to evaporate any water out of the casing before you put he camera in?

What are the best steps to take to make sure you don't fog up?

B A H

Originally posted by gdguide

Just wondering what tips/steps you take in making sure your housing doesn't fog up. Do you keep the camera/housing in a cool place like a cooler before you go in the water? Do you put the silica pacs far in advance? Do you heat the housing in the sun to evaporate any water out of the casing before you put he camera in?  

 

What are the best steps to take to make sure you don't fog up?  

 

B A H

Why it fog up?

In order to avoid fog up, we should know why the housing fog up. The moisture cause fog up is sourced from the housing and mainly from the camera which can absort a large amount of moisture inside its components. The moisture may be vaporated by the heat from the camera and much more heat from video after turning on for sometime. The evaporated vapour then condense on surface of the housing or lens which are at a lower temperature as heat is conducted away by the outside water. It is much easier to become fog up in video housings as much more heat is evolved from video.

How to eliminate fog up?

1. Reduce the amount of moisture inside the housing and camera/video by a) using hair dryer to pre-heat both the housing and the video; B) heat up both the housing and the video under the sun and allow the evaporated moisture to escape; c) use chemical to absorb moisture (not too effective as it takes long time for the process)

2. Control the raise of temperture of the camera/video by avoiding prolong and continuously switching on.

3. The more practical and efficient solution is to use a double lens which is a standard feature for all housings produced by "10 Bar Underwater Housings" for all their Video Housings.

As the air in between the two lens is a poor conductor of heat, the inner lens is always at a temperture higher then the other surfaces of the housing which is in direct contact with the water. Therefore the moisture vapour will condens on the cooler housing surface and will not fog up the lens!

The easiest solution to prevent fog up is to choose housings with double lens which effectively eliminate the chance of fog up.

lc

[Edited on 2-22-2002 by lc]