video housing question

[Groundhog246]

I'm currently working on a video housing (thanks Padipro for the help). Thinking about the lens port. On my UW 35mm fogging has been an issue, especially with a glass port and the rest of the housing plastic. I was wondering if 2 pieces of glass with a gap filled with dry air, like a thermopane window would help prevent fogging. Something like this:
___
O O

It would have the outer lens well sealed with an O ring to prevent water intrusion and the inner lens a smaller o-ring just to be airtight.

Thoughts, opinions, suggestions are welcomed.

 

[dvoodoo83]

well fogging is caused by thr temp diffrences and the water in the air so get rid of the air in it some how but i think your idea might work for the lens area just dont forget about condencation in the housing wicth could short out the video cam. good luck your braver then me i wouldnt put my cm into something i built

 

[Padipro]

I've never had any trouble with fogging on my housing, even using it here in humid south Florida. If you're making the housing out of PVC with Plexiglas lenses I don't think you'll have any trouble either.

 

[Groundhog246]

Plan to try just shooting through the big piece of plexi and see how that works. If I decide it's not clear enough, I plan to try adding a small glass port and that's where I see fogging as an issue. The difference between Florida nad here, is I dive regularly in 50F (and colder) water. Down to the temps in the upper 60's with my 35mm, fogging has never been a problem, low 60's and into the 50's it has, but not every dive.
My thoughts were, that with a gap between the 2 pieces of glass and dry air in there and with the warmth from the camera, that the outer lens would be at ambient (cold) and the inner lens would stay somewhat warmer, as it's not touching the water.
Will see what happens shooting through the plexi and will post follow up if I decide to attempt the two layer project.

 

[in_cavediver]

Plan to try just shooting through the big piece of plexi and see how that works. If I decide it's not clear enough, I plan to try adding a small glass port and that's where I see fogging as an issue. The difference between Florida nad here, is I dive regularly in 50F (and colder) water. Down to the temps in the upper 60's with my 35mm, fogging has never been a problem, low 60's and into the 50's it has, but not every dive.
My thoughts were, that with a gap between the 2 pieces of glass and dry air in there and with the warmth from the camera, that the outer lens would be at ambient (cold) and the inner lens would stay somewhat warmer, as it's not touching the water.
Will see what happens shooting through the plexi and will post follow up if I decide to attempt the two layer project.

I have an Ikelite and have seen fogging on occasion. What I found works the best is to blast either argon or scuba air into the housing before sealing it. This dramatically drops the moisture content of the gas inside the housing. Less moisture means less water to condense. Since I started doing this, I haven't seen any problems.

Mike

 

[Groundhog246]

I've tried blasting dry air (from my cylinder) into the 35mm housing, with mixed results. Experimented with using a fairly airtight bag (bag designed for loading film into developing canister, used to do a lot of b&w stuff in my own darkroom), and filling emptying a couple of times, then sealing the housing. Also gave mixed results, especially if I wanted to change rolls between dives.
The video camera I'm working with has a power down mode, that if you don't record for 5 min it powers down about 90% (turns off the LCD among other components) to save the battery charge. Pressing the "rec" button wakes it up again, press again to record. I've ordered a long life battery for it and I'm hoping the combination will let me seal the camera in the housing, with a couple of packs of silica gel at least a couple of hours before we dive (ie first thing in the morning). The tape's good for 90 minutes, so can probably wring two dives out of it, without having to open the housing, as i'm not likely to tape every minute of our dives.

 

[dvoodoo83]

good luck with it let us know the resoltes dvoodoo83