Re: [Leica] Re: Leica Users --Dry Cabinet

[Karen Nakamura <mail@gpsy.com>]

My point wasn't that 20C would cook your camera, but that if you left 
a 60 watt bulb in a metal case with an outside temperature of 20C, 
then the temp inside the case will quickly reach 40C or 50C. Very bad 
for most things.  Try this at home: put a 60 watt light bulb inside 
a plastic cooler and see how soon you melt a hole in the corner.

In a hot/dry atmosphere, your older pre-plastic Leica might be happy, 
but the other stuff you might have in with it might not be. Plastic 
lens caps, the plastic film components, the plastics in the straps 
will outgas. In a dry climate, the leather of your   straps, cases, 
etc. will dry out.

A cool dry climate is much better than a hot dry climate. That's my 
basic point.

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On a cooler topic:

Here's a picture of one of the Japanese units:

http://www.toshu-ltd.co.jp/gaki/electronics/sample/drycabi2.html
http://www.toshu-ltd.co.jp/gaki/electronics/sample/drycabi-pelche.html


It uses the Peltier effect to reduce the temperature and thus the 
moisture content of the atmosphere. The goal is to reduce relative 
humidity to 30%.  As us Minnesotans know, the colder the atmosphere 
the less moisture it can contain.  My guess is that the unit operates 
two ways:

  * By condensing moisture onto the Peltier plate
  * By reducing the moisture holding power of the atmosphere by 
reducing the general temperature

As an experiment, try checking the humidity of your refrigerator or 
freezer. It's actually quite low. Of course the moment you open it, 
the outside air rushes in, moisture condenses on all the cold 
surfaces etc.


Karen




>Karen
>
>Check your mathematics.  20 degrees Celsius is 68 Fahrenheit.
>
>It is humidity that is ruinous to the subject of the original discussion.
>A refrigeration unit will INCREASE the relative humidity of its
>space.
>
>A Leica can live a looooong life at 90 F.
>
>Jerry
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