Silica Gel Usage

[HowardE]

So far it sounds like most do not use silica gel in their housing. For those that do, what is your souce for packaged silica gel and your technique of using it? Thanks

To keep it on topic...

When I DO put a silica gel pack into my housings (video and wife's P&S Camera) I use one from the many packages we receive at our (gift) stores. Not everyone has this option available to them.

You can go to a camera store and get some like these http://www.adorama.com/IOMSGD.html?sid=11697355373960025

and they should easily fit between the camera and the housing. I usually friction fit them somewhere where they can't make their way in front of the lens

 

[MarkH]

I've had occasional fogging problems with my old manual SLR and with my video camera. I'm guessing it's a combination of higher Summer air temperatures and always-cold water. I keep the small dessicant packs from when I buy shoes, camera stuff, etc. If they are too small, I package them together in the cut-off toe of a thin sock. I recharge them before every dive day by microwaving them (without the sock as it can melt) for about 2-3 minutes on high (sometimes they can scorch if I leave them for too long). I put this package in the housing somewhere where it won't move around too much and seal it all up. I usually do this at least an hour before diving. One source for dessicant packs is one of our local camera stores that keeps hundreds of them in a drawer and gives them away to anyone that asks for them.

 

[Warren_L]

There may be other considerations regarding p&s cameras versus dSLRs and fogging issues that may be worth consideration. It may be possible that a typical p&s housing may be such that it has more air to inner surface area than a dSLR housing, or perhaps p&s housings tend to be thinner by nature and the inner surface cools quicker than the typical dSLR housing?

 

[Digger54]

Thanks guys for the useful information. cheap or free sounds good to me. The bigger packets that they sold for the gun safe were a bit pricey. Even the olympus branded packets at adorama.com are pretty cheap.

 

[joewr]

Hey, Gang,

I have been chatting with camera cos. and housing cos. today and now I know the answer!

I need to scoot now and will post the detailed info later. The bottom line: it is the housing that is the issue here. Fogging nearly never occurs with metal housings like my Subals. It only occurs with plastic housings such as the ones Ikelite produces. And that is why I never saw it. Further, it can happen with DSLR's, but is very unlikely with film cameras. Stay tuned and I will tell you what I learned...if there are any of you still hanging around....

I can explain why and it makes a whole lot of sense.

And for Digger who was so patient with me whilst I wandered away from his question: thanks for the patience...and pardon an old chemist...
Also for Digger, the word on the street is dessicant packs are the way to go...but, then you already know that...:blinking:

joewr...thinking...you meet such nice people here...

 

[Digger54]

Hey, Gang,

And for Digger who was so patient with me whilst I wandered away from his question: thanks for the patience...and pardon an old chemist...
Also for Digger, the word on the street is dessicant packs are the way to go...but, then you already know that...:blinking:

joewr...thinking...you meet such nice people here...

Digger --Majored in Vertebrate Zoology, Minor in Chemistry -- so I guess I'm an old minor chemist. The physics of it, I can handle, just needed info on the application.
Thanks.

Also... After giving it some thought I think I can guess what you will say about no fogging problems in metal housings and why plastic will fog worse. I'll wait to read your comments first.

Again... Thanks.

 

[HowardE]

I have a plastic (Ikelite) housing, and have yet to have any fogging issues at all. I've only done about 100 dives with my setup, so I can only state what I have seen from experience.

My wife's camera (canon S70) in the Canon Housing did fog up several times, until we put the gel packs in. Problem solved.

 

[Diver Dennis]

The housing I was talking about was an Ikelite. I've never had problems with my Ike either howarde. I'm pretty sure the heating up of the air from the P & S camera is the culprit.

 

[joewr]

Digger --Majored in Vertebrate Zoology, Minor in Chemistry -- so I guess I'm an old minor chemist. The physics of it, I can handle, just needed info on the application.
QUOTE]

Chem Minor...well, now we are talking! As the Aussies are fond of saying, "Good on you, Mate!" And now I know where to go for my fish anatomy questions!

Okay, here is the deal...and I will try to avoid as much technojargon/baffle-them-with-bs as possible.

It all has to do with what are called heat transfer coefficients...that is how effective a material is at transferring heat. Metal is very good, fiberglass home insulation is bad. And now the key: glass is good at transferring heat....plexiglass is NOT good at it.

The effect of where you close your housing: if the dewpoint (temp at which the water vapor in the air condenses to liquid water) of that air that is trapped in your housing is key If that dewpoint is the temp of the water in which you are diving, you COULD get condensation.

The effect of camera heating: if you have liquid water--usually it will be a very thin film that you cannot see--the heat generated when electrical current flows can vaporize the water. If the air in you camera is near the dewpoint, this can put it past the dewpoint, causing condensation. One more thing...digital cameras use more electricity that their film counterparts and that is one reason why this would only rarely happen on a film camera.

Now one more fact that may not be obvious...things get colder by losing heat, not gaining cold. Thus, heat is what moves, not cold.

For plastic housings like the Ikelite, the heat moves through the glass preferentially, cooling it preferentially...i.e., the glass temp is lower than the plastic temp and, whoopee, condensation if it is at the dewpoint. for metal housings, the temp is more or less uniform and a cold spot is not preferentially on the glass.

So, according to the good souls I chatted with, dessicant is a good idea...which, thanks to Digger's persistance and patience--not to mention Howard's, Dennis' and the rest of the Gang--we all now know.

And, once more, I want to thank all of you for engaging in a darn interesting thread...and being so darn nice to whole time...inspite of my slow learning process.

joewr

 

[diver_pirate]

There is always humidity to one degree or another. The thin packets or round sticks pull the moisture out of the air. I even store the camera for long periods with these inside so the salt moisture laden air gets asorbed in the packet rather than corode the electronics or grow crystals on the lenses. I found packets that are about 3/4 x 1-1/2 x 3/16 that slide between the case bottom and the camera. There is no motion or dust as the paper envelope is made of a nonwoven permeable fabric. They turn pink when they are asorbed and you put them in the oven over night (without the camera and case) on the lowest setting and they become dry and able to reuse. Put them in a plastic bag that seals well and use them all week on a trip. --No fog or growth.
DP