Suffering from the Mother of all cold viruses but with just enough energy left to have found the following. Gives detail beyond that of Tom Hillson's reference but is more of a mental challenge than an instant fix! http://johnlind.tripod.com/science/scienceexposure.html My thanks to Tom for his info which is, no doubt, a time saver for many of us oldies with old cameras and meters and too mean to buy another meter.
With all the variations in shade, filtering through glass,polycarbonate, polyethylene and so on, I imagine an approximation to be adequate. Good luck John Stanley _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
