Re: Lights

From: Walter Knapp (wwknapp@mindspring.com)
Date: Fri Mar 21 1997 - 12:12:56 PST

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Date: Fri, 21 Mar 1997 20:12:56 +0000
From: Walter Knapp <wwknapp@mindspring.com>
To: cp@opus.hpl.hp.com
Message-Id: <aabcdefg1041$foo@default>
Subject: Re: Lights

Here is the method of getting footcandles in a greenhouse using a
camera.

You need a camera that can be set manually.

Set the asa at 200.

Set the shutter speed at 1/125

Aim the camera at the light source. (The greenhouse glazing)

Read the f-stop for a correct exposure.

If the f-stop is: Your Greenhouse light level is:

       2.8 32 footcandles
       4 64 footcandles
       5.6 125 footcandles
       8 250 footcandles
      15 1000 footcandles
      22 2000 footcandles

This comes from the "Greenhouse Gardener's Companion" by Shane Smith.

Walt
wwknapp@mindspring.com

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