Humidity around 45%

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Archive 2009 · Humidity around 45%

cgardner
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p.2 #1 · Humidity around 45%

fmikio wrote:
Also, about the condensation.....

Condensation is a result of warm moist air encountering a colder object.

Case in point is pouring a very cold beer into a case on a summer day; as the beer cools the glass condensation forms on the outside of the glass, provided the beer stays in the glass long enough

On a cold winter day the RH outside is low because cold air can't hold much moisture in vapor form.

Whether of not condensation will form on your cold camera when you bring it back indoors will depend on what level of RH there is indoors. I run several humidifiers in winter and try to keep indoor RH in the 35% range. If shooting outdoors for any extended period I'll remove the CF cards and leave the camera bag in the unheated but warmer than outdoors garage to warm up a bit before bringing it indoors.

Occasionally in the drab winter months I'll pay a visit to the National Arboretum, a nice little gem a stone's throw from the US Capitol. The conditions there are very hot and humid in the tropical plant sections so I err on the side of caution and stay in the outer, more temperate perimeter and shoot there.

Nov 10, 2009 at 01:49 PM

David Baldwin
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p.2 #2 · Humidity around 45%

Here are the facts:

http://www.zeiss.com/c12567a8003b58b9/Contents-Frame/29cd78d56723da79c12571180042df52

"Reduce the relative humidity to less than 60% (never under 30% as it is dangerous for the instrument"

On this basis 45% sounds great. My bag today is at 51%, I check my digital hygrometer thingie in my pelican case about every 48 hours to stay within the 72 hour range.

Nov 10, 2009 at 03:00 PM

ChrisDar
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p.2 #3 · Humidity around 45%

Gochugogi wrote:
Only 45%? Sheesh, don't move to Hawaii: it's typically 70-90% and gear does just fine without desiccant. Humans don't fare as well and it makes for a lotta sweaty 'n stinky folk.

Or you could move to Arizona where we've been averaging around 8 to 9% and lower lately. Even when I lived in the mountains of Colorado we were always around 10% even during the winter snows.

When people moved to town from normally humid places their furniture would all crack when it dried out. I've seen beautiful heavy wooden kitchen tables with half in cracks down the middle after moving from back east where the humidity was high.

I'll take dry any day.

Nov 10, 2009 at 09:33 PM

Paul B
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p.2 #4 · Humidity around 45%

RDKirk wrote:
Humidity is relative. 45% in your location, Canada, is not the same as 45% in Florida or Texas (of course, AC inside would change that.) But that's pretty dry for a colder location. Dessicants can't hurt, though.

When a hygrometer gives you a reading for "relative humidity," it already take temperature into account...that's what's relative about humidity.

Not sure I follow you here. Regardless of whether it takes into account temperature, there's a difference in the water content of air that's at 45% relative humidity in 95 degree temperatures and 45% relative humidity in 65 degree temps, right? So it's the absolute amount of moisture in the air relative to the maximum absolute amount that can be held by the air (which varies depending on the air's temperature; warm air can hold a larger amount.)

Of course, there's also "absolute humidity" but the type of humidity most often discussed (newspapers, weather channel, etc.) is relative humidity. In discussing issues of absolute humidity people typically are essentially doing that by talking about dew points (or 100% relative humidity.)

Nov 10, 2009 at 09:48 PM

RDKirk
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p.2 #5 · Humidity around 45%

Going back to the OP's question:

I keep my gear inside a flipside bag in the closet. I bought those humidity measurers and it's around 40~47%. Is this ok or is it better to have some desincant packs also ?

He's not talking about going inside and outside, he's talking about keeping his gear in a bag in a closet. I am presuming he's worried about fungus damage, not condensation.

If he is indeed measuring the humidity inside the bag, then that is a safe level from fungus damage without dissicants. If he keeps the equipment surrounded by air that is less than 70% humidity, that will prevent mold growth. The shell of the mold spores must absorb moisture from the atmosphere, and unless the atmosphere contains at least 70% of the moisture it can hold at any given temperature, the air will be too dry for the mold spore to absorb moisture from it.

With regard to dissicants, they are of little practical use except for longish term storage in a container that retards air movement well and won't be opened during storage.

If indoor condensation coming from cold outdoor weather to warm indoors is the worry, then the answer is to leave the equipment in the bag until it warms up. Then take the equipment out (although most people don't live in houses humidified to more than 70% during the winter in Canada).

Nov 10, 2009 at 11:04 PM

fmikio
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p.2 #6 · Humidity around 45%

RDKirk wrote:
Going back to the OP's question:

I keep my gear inside a flipside bag in the closet. I bought those humidity measurers and it's around 40~47%. Is this ok or is it better to have some desincant packs also ?

He's not talking about going inside and outside, he's talking about keeping his gear in a bag in a closet. I am presuming he's worried about fungus damage, not condensation.

If he is indeed measuring the humidity inside the bag, then that is a safe level from fungus damage without dissicants. If he keeps the equipment surrounded by air that is less than 70% humidity, that will prevent mold growth. The shell of the mold spores must absorb moisture from the atmosphere, and unless the atmosphere contains at least 70% of the moisture it can hold at any given temperature, the air will be too dry for the mold spore to absorb moisture from it.

With regard to dissicants, they are of little practical use except for longish term storage in a container that retards air movement well and won't be opened during storage.

I didn't measure the RH inside the bag but inside the closet. I just took all my gears out from the bag and put them inside the drawer (those walmart plastic drawers) and it's inside the closet. I guess I will not have trouble with air circulation since it's gonna be outside the bag.

If indoor condensation coming from cold outdoor weather to warm indoors is the worry, then the answer is to leave the equipment in the bag until it warms up. Then take the equipment out (although most people don't live in houses humidified to more than 70% during the winter in Canada).

Since my house during the winter is something like 30~40%, would that mean that I wouldn't have problem (or maybe less time to warm) with condensation ?

Nov 11, 2009 at 12:39 AM

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