Corpze:
Thanks for your very good answer, i will use the meter for my own, to measure different sites where i do my astrophotographing.For the ZP i have a luxmeter that i can use, it will not be scientific grade, but good enough for me!
It´s just one thing left, does anyone know what kind of "lensmodule" i have marked on the picture?
Oh, and one more question; The code i am gonna start out with is this: How to: Light to Frequency Converter - TSL235R? - #17 by madepablo - Interfacing - Arduino Forum
But will that work? it is written for a Arduino duemilanove?