Quote Originally Posted by Bill Burk View Post
I'd recommend an artificial light source. I think actual daylight is too hard to control, it may vary too much to give you consistent results (so while it is the correct light source to match your shooting planned conditions, it's not as good for testing since it is different each time you use it).Your test sounds simple enough that you could make a "light box" to hold behind the white translucent perspex that turns it into a "light table"
Thanks Bill. After my interesting results with two considerably different colour temperatures giving noticeably different gammas, it makes sense to control for that by using an artificial source to provide a more repeatable colour temperature.