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Varicam's moisture sensor


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#1 Scott Fritzshall

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Posted 06 November 2006 - 01:44 AM

At the end of this month, I will be shooting a project on a Varicam that requires heavy use of steam/fog. I was just recently informed that the camera has a moisture sensor of some sort, and the camera will automatically shut off if the air is too moist. I'm not sure whether or not our fog or whatever we use will trip the sensor. I would think that we could just wrap the camera in a plastic bag or something, but I'd be worried about cutting off airflow and having it overheat.

Is there any good way to deal with this or are we going to be wishing we were shooting Super16?
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#2 jan von krogh

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Posted 06 November 2006 - 02:58 AM

Is there any good way to deal with this or are we going to be wishing we were shooting Super16?


i cant speak about varicam (were cinealta/35-house and upcoming red)

we had recently a sony 750 rented out to a horror-fullfeature - they were shooting in the woods, - degrees celsius to +40 celsius in minutes, sun, condensation, generally everything humid.

camera had moisture alarm 2 times.
we gave the usual tip:
use raincoat with lots of "the bagged stuff you get with new electronics which absorbs humidity & fluids"™... i don´t know the english word for it, so please forvige me using the descriptive name...
fixed it for them, should work for you.

method b would be a lowprice underwater bag with overpressure - they are intended for underwater shooting in low depths (1-4 meters) and don´t cost a fortune, ~400-900 euros IIRC. makes it a bit harder to access the camera however.

heat isn´t an issue with the sony 750, with the panasonic i don´t have experiences.
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#3 Phil Rhodes

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Posted 06 November 2006 - 12:42 PM

Hi,

Silica gel.

Only it's not a gel.

Phil
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#4 Hal Smith

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Posted 06 November 2006 - 12:49 PM

If you use silica gel inside a bag, be certain it's fresh. The silica gel I've always used is a deep blue when fresh, changing to a rose red when it's dehumidifying capacity is exhausted. I don't think the stuff packaged with electronics has the color indicator but I could be wrong.

If exhausted, it can be recycled by heating in a microwave oven.
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#5 Scott Fritzshall

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Posted 06 November 2006 - 01:26 PM

Hi,

Silica gel.

Only it's not a gel.

Phil

Where can I get this, and how much does it cost?

Are there any issues with air circulation with this method?
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#6 Robert Hughes

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Posted 06 November 2006 - 01:27 PM

Caution: silica gel tends to release minute particles of carcinogenic silica when heated. Best not to use your kitchen microwave or oven for silica gel drying and food preparation simultaneously.
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#7 Hal Smith

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Posted 06 November 2006 - 03:31 PM

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Caution: silica gel tends to release minute particles of carcinogenic silica when heated.

I didn't know that, I Googled for an MSDS (Material Safety Data Sheet) for silica gel and came up with this:

*** Silica gel is used to absorb water from gases. The gel itself is comparatively harmless, although silica dust is harmful if inhaled. However, silica gel often contains a small amount of an added chemical to indicate whether the gel is still effective at absorbing water. This indicator may be cobalt (II) chloride, which changes from blue when the product is dry, to pink when it is nearly exhausted. Cobalt compounds are suspected of being carcinogenic, and may cause sensitization or an allergic reaction, so care should be taken that silica gel is not inhaled.

So interestingly enough, the problem lies with the cobalt chloride indicator, not silica gel itself outside of a dust warning.
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