Go Pro Fogging

[archiebald]

There is no heater. The "Integrated Battery Warmer" is the main image processing chip and it naturally runs very warm. The battery warmer was not something they intentionally added to keep the battery warm, it was already there. (But hey, why not make a marketing gimmick out it if you can.)

Yep, perfect.

Their marketing is somewhat like claiming a railway steam locomotive had been specially fitted with a nice big log fire just so you could have a place to roast your chestnuts.

 

[JTemple]

Has anyone tried to buy dessicant paper, other than the GoPro branded stuff? I found this site:

Desiccant Paper - SorbentSystems.com

A pack of 5 8"x12" sheets is only $28.90.

 

[archiebald]

I am not sure why so many people seem dead set against buying the original GoPro item. It is not so expensive, you know it is going to fit, you know it is going to work and most importantly it is highly re-usable so any "cost saving" is virtually meaningless.

 

[JTemple]

When you are on a 2-week dive trip, unable to recharge the paper, you would have to buy several packages to have enough usable, active sheets to last the trip. And I do think they are expensive. Very expensive compared to normal dessicant gel packs. So I've been looking for an alternative.

 

[archiebald]

Aha!!, that's why I didn't understand....the chance of me being able to get two weeks of diving in, is slimmer than a very slim thing after 3 months on a crash diet.

 

[IyaDiver]

BTW, it's "desiccant", not "dessicant" and you are mixing things up. I only said heat on the inside will not increase fogging.

Actually, when you put active desiccant in a casing then seal it up something IS happening but it is invisible. The air trapped in the casing will become dryer down to a new equilibrium point.

Ignoring desiccant for a moment, simply adding heat on the inside will do nothing to change the moisture content of an enclosed casing. How can it? The same number of water molecules will always be present in the trapped air so the dewpoint temperature of that air remains constant. Remember, dewpoint represents an absolute value of the water content, not a relative value as in RH%. In fact adding a heat source inside will help to warm the inner surface of the casing so that it might just keep the surface above the internal air dewpoint temperature and stave off condensation a little longer when the case is put into cold water.

When you place a camera inside the casing and operate it, you are not simply adding heat. You have also added moisture from within the camera itself which is being driven out of the camera and into the casing thereby actually raising the dewpoint temperature of the air in the case. To an outside observer this might make it look like the heat source has caused the fogging but the truth is that the camera has "contaminated" the case with its own additional moisture content. I would recommend also conditioning the camera before placing it inside the casing. I always leave the camera in the open case in front of an air conditioner for at least 30 minutes prior to sealing it.

Cooling the outside of the casing on the other hand, has a profound effect because effectively you are lowering the inner surface of the casing temperature and if you continue to lower it below the dewpoint temperature of the air trapped inside , then condensation will start to appear on the inner surface.

The reason why the one with desiccant does not fog up (until much cooler) is because you have reduced the dewpoint of the air in that casing. That is what desiccant does. It absorbs the free moisture in the air inside the case so that you can drive the casing surface temperature lower before condensation will start to appear. But even adding desiccant will not work if the outside temperature is low enough - there are practical limits.

Sorry if I am coming across as a know it all - that is not my intention but I work in the engineering plastics industry and give training courses to customers on the use of desiccant drying systems working to a dewpoint of -40degC and below. Dewpoint temperature is quite difficult to get your head around at first - the majority of people don't understand it.

Archie is right.
It is all about dewpoint of the air which means the dryness of the air which indirectly means the capacity of the air to hold water vapor which is water in gas form at X temperature at Y humidity and at 1 ATM.

One can't start with higher than 100% humidity ambient air when placing a GoPro camera, in a GoPro housing. Once you hit 100% RH, you get liquid water already

The next big problem is the ambient temperature. The hotter the ambient temperature of the air, say 90% relative humidity, and we heat up the air hotter, that hotter air will have the capacity carry more water moisture by temperature rise alone. That is part of gas law that we can not escape from.

Tropical country is the worst of the worst when it comes to ambient air capable of fogging a camera lens internal side.
A GoPro housing even without a camera inside it , meaning the air space volume is not as high as a housing with camera inside it, at the most is 100cc. Or 0.1 liters.

This 100cc of air and ambient temperature of the air and humidity of the air, is the limit to how much the air can carry water vapor......which when this air is cooled aka reaching its dewpoint, it has to release the water vapor ( gas ) as fog ( very fine liquid ) or droplets of water ( if enough water vapor turning into liquid ).

Now the key is to understand how much water vapor are we talking about in a housing as small as a GoPro ?
This is the maximum water vapor in air at 100% humidty at 1 ATM.

Cel = Celcius , temperature

grams/cubic meter is the water content ( vapor ) of the air in grams per 1 cubic meter ( 1000 liters ) of air.
Grams is the same as milliliter or as CC aka cubic centimeters.

1 liter = 1000 milliliters ( milliliters is also known as CC or cubic centimeters )
1 kg = 1000 grams
Density of fresh water is 1 gram per 1 milliliter or 1 liter of water is 1kg of weight.

Cel .grams per Cubic meter of air
0.0 . 4.487
1.0 . 5.196
2.0 . 5.563
3.0 . 5.952
4.0 . 6.364
5.0 . 6.802
6.0 . 7.265
7.0 . 7.756
8.0 . 8.275
9.0 . 8.824
10.0 . 9.405
11.0 . 10.020
12.0 . 10.67
13.0 . 11.35
14.0 . 12.08
15.0 . 12.84
16.0 . 13.64
17.0 . 14.49
18.0 . 15.38
19.0 . 16.32
20.0 . 17.31
21.0 . 18.35
22.0 . 19.44
23.0 . 20.59
24.0 . 21.80
25.0 . 23.07
26.0 . 24.40
27.0 . 25.79
28.0 . 27.26
29.0 . 28.79
30.0 . 30.40
31.0 . 32.08
32.0 . 33.85
33.0 . 35.70
34.0 . 37.63
35.0 . 39.65
36.0 . 41.76
37.0 . 43.97
38.0 . 46.28
39.0 . 48.64
40.0 . 51.21

Now, look at your ambient temperature and assuming 100% humidity is where you are ( for maximum impact sake ), the maximum amount of water vapor in the air in the housing is that grams ( or milliliter or CC ) figure.

Since 0.1 liter of air space compared to 1000 liter is 0.1/1000 = 0.0001
The grams on above table x 0.0001 is the maximum water vapor "parked" in the air in the housing, based on the ambient temperature you are at. Just remember this, our air contained water but we cant see it because it is in GAS form, hence the name water vapor. Fog or rain is water in liquid state. Ice is water in solid state. The gas form of water is what many people get confused with because they can't see it.

Say super duper hot country and humid at 35 Celcius, you have 39.65 grams x 0.0001 = 0.0039 grams of water vapor able to be turned to very fine mist called FOG , in a GoPro housing...........when the dewpoint is reached.
How little is 0.0039 gram ? It is very littel by weight but plenty enough to fog up a housing lens of GoPro size.
20 drops of water is 1 gram. So 1 drop of water is 1/20 = 0.05 gram
1/10 of a water drop is 1/200 = 0.0005 gram.

Take your sunglasses, in a tropical country and do that AHHHH thing with the air from your mouth, will the lens asy fogged up..?..sure will.
Is your sunglasses lens any bigger in surface area compared to a GoPro lens.....NOPE, near the same or even less.
So that explained to us how little water vapor in air can fog up a lens of a GoPro from INSIDE.

So why is the lens the GoPro housing first one to fog up and not the internal polycarbonate whole body ?
Because the lens is glass, it transfer the cold of the seawater much faster than the polycarbonate body of the camera housing. So as camera operates in the housing, it heats up the air inside the housing. On the other side of the housing, the external that is, the sea water or the lake water will cool the housing from outside, but lens get cooler first and this cooler temperature cools the lens totally , its whole thickness and therefore the internal side of the housing lens will be as cool as the surrounding water in no time. Let's assume the water is a mere warm 29 Celcius.

At 35 celcius, assuming 90% humidity was the air the internal of the housing had ( not a 100% ), the dewpoint temperature is a mere 33 Celcius. See for yourself : Dew Point Calculator
So anytime the surrounding water have allowed the housing lens on the internal side of the housing, to cool down to under 33C, fog will happen on that internal lens. The air closest to the lens ( internal side/in the housing ) will also be cooled and has to "surrender" its water vapor as liquid water aka fog. Thus fog will build up slowly making the lens foggier and foggier as the lens is being cooled more and the air inside the housing becomes cooler and cooler making more and more of the total air inside the housing reaching its dewpoint temperature or easier to remember as JUICED OUT temperature.

So by gas law, we have proved that to fog an internal side of a GoPro housing is so easy if supported by warm and moist air to begin with and the water the user dove in, is at least 3C cooler. Even a 2.5C cooler water will get you fogging , but much later.....because 2.5 C temperature difference and humidity at 90% or more, it is enough to JUICE OUT the water vapor in the air, 2 C difference is what that slider table showed.

If anyone said , I had more than few drops of water inside my GoPro housing when it fogged.
Yes, but that only and can ONLY happen when we OPEN the housing and allow more air ( ambient air ) to JUICE OUT its water vapor by contacting a much lower temperature of the plastic material surface of the internal of the housing. This will be the same as taking out a small cool glass/cup from a 4 to 10 degree Celsius fridge, in a 30C tropical country. Try it and see how wet the glass/cup surface will be within 2 minutes.

How do we get fogging on the camera housing external ?
Easy, if your camera is already cool enough ( its housing ) at 25C because you hit a thermocline, you then surfaced to a tropical ambient temperature of 30C......guarantee your housing external surfaces will start to collect fine water mist.
Same a camera kept inside a nice air conditioned cabin at 23C for hours, in a tropical Live On Board, suddenly you need to take it out of the cabin to take photo of the islands and the external ambient temperature is at 30C . Your camera will fog for sure and fast , very fast.

Why Scuba air being injected to a GoPro housing internal air cavity ?
Because scuba air, if the compressor is properly maintained, will be super duper dry all the way to -50C dewpoint or drier if filter cartridge is very new. My compressor production air can go down as low as -70C Dewpoint easy.

What humidity equivalent is a -50C ?
Temperature, Dewpoint, and Relative Humidity Calculator
Choose Celcius
Fill up Temperature to be 30C ( that is the ambient temperature )
Fill up Dewpoint to be -50, that is how dry a good scuba air will be
See that it is equal to an air supply with temperature of 30C, with "wetness" of only 0.15% relative humidity.

So how does a scuba air of dryness value -50C Dewpoint do good for us ?
In theory, that value of -50C means : you need to cool the down the air to a bit cooler than -50C to juice out any water vapor out of it .

In practice, injecting a scuba dry air into a GoPro internal air cavity is very good, as you remove the water vapor source.

In a GoPro antifog scenario, you remove water vapor by keeping it in the antifog water vapor adsorber material.
You are then placing a small "water vapor bank" or water vapor vampire ..........so to speak.

Starting with less water vapor in the air cavity of a camera housing is always better.


Can we really get -50C dew point performance by injecting scuba air into a GoPro internal cavity ? This is assuming one can dive in -50C of water hahahahah, -2C is the coolest for a sea water freezing into ice if I am correct.
You can never get even -10C dew point performance by injecting scuba air into a GoPro internal cavity but sure much better than air cond air and the like.

Why can't we get -50C dew point dryness if the air we inject into the housing cavity is a -50C dew point ?
This is because, once we mess with super duper dry air, even copper the so called METAL does absorb water vapor.
The polycarbonate housing, the white sealing silicone gasket, the GoPro camera itself and its electronics, they can not be dried down to -50C easy. For a dewpoint sensor to read as low/dry as -70C for my system, I need to pass thru it -70C dry air for at least 4 hours non stop. Everything in the air line has water vapor.....very very minute trace.

Ok, I hope all clear on fogging and dewpoint.

Happy GoPro-ing guys.........
.

 

[JTemple]

Has anyone tried to buy dessicant paper, other than the GoPro branded stuff? I found this site:

Desiccant Paper - SorbentSystems.com

A pack of 5 8"x12" sheets is only $28.90.

After exchanging several emails with the Sales Manager at Sorbent Systems, I can guarantee (Yes! Guarantee!) that this paper will work and fit in the GoPro housing. All you'd have to do is cut it down to size. 5 8"x12" sheets for the price of 2 packages of the GoPro branded stuff. A significant savings. Feel free to PM me if you would like more information. I will be ordering some!

 

[toozler]

Hi! Being on a budget (and after buying the camera+dive housing), I found the price of the official GoPro anti-fog inserts a little too high for what they are. Knowing the risk of the camera fogging up, I decided to go the DIY way with what I had laying around.

You know how Brawny brags about being the most absorbent paper towel out there? Maybe it is true... I cut two long strips (about 4" long, 1" wide) and folded each into dimensions similar to the official strips (maybe 1x0.5"), put that on a tray and "baked" it on a preheated toaster oven for a couple minutes to get rid of any moisture already in the paper. After folding them again, those went straight into the camera housing, fitting snugly on the sides of the camera itself.

I did a whole hour of free diving, opened the housing several times, did two 50 minute dives, opened the housing again, went swimming, and still no fogging to be noticed.

I like JTemple's idea, let me know how it works if you try it out!

 

[danpass]

Has anyone tried to buy dessicant paper, other than the GoPro branded stuff? I found this site:

Desiccant Paper - SorbentSystems.com

A pack of 5 8"x12" sheets is only $28.90.

nice find.

All the GP packs at best buy have an indicator in them "if blue then dessicant active". they are referring the typical luggage dessicant pack they thrown in.

well ...... the indicators are always all blue lol (here in Miami anyway)


I think I'll grab a set of this stuff since it can be cut to shape.


Just out of curiosity; did they mention any advantage to purchasing the 'inactive' type? Perhaps it would help with activating only a section at a time to preserve the rest?

 

[JTemple]

No, I didn't ask. But if you email them, they are very responsive. I had a nice exchange of emails with the Sales Manager there. Let us know if you find out anything.