Re: Sticking my neck out - again

     >Do you have a 35mm camera with a built-in light meter? One of the 
     >"older" kind, in which you manually set the shutter speed, ASA or DIN 
     >film speed, and hand-adjust the f-stops?  
     I found an approximation for converting readings from a camera's light 
     meter into foot-candles (Source:  Greenhouses--planning, installing 
     and using greenhouses.  Ortho Books, 1991).
     Set your camera to ASA 25 and 1/60 shutter speed.  Aim and focus the 
     camera so the object you want to measure fills the viewer.  Adjust the 
     f-stop until the needle indicates the correct exposure.
     If the object you are metering is WHITE, then:
     f-stop     foot-candles
     2          100
     2.8        200
     4          400
     5.6        800
     8          1,600
     11         3,200
     If the object you are metering is GREEN (like a plant leaf), then you 
     must increase the f-stop by two settings to get the correct amount of 
     light (e.g., if it reads f5.6, add two f-stops, resulting in f11 and 
     3,200 foot-candles).
     A camera's light meter only reads reflected light, so if you measure 
     from something white (e.g., 90%+ reflectivity), you are getting a 
     pretty good measure of the amount of incident light.  Green plants 
     reflect much less light (about 20%), so you must adjust your f-stop