measuring light levels.

[james mickelso]

Virtually any light level apart from full sunlight is fine for phals. They will take from pretty deep shade up to nearly full sunlight. That fist size patch of full sunlight is probably smaller than you think. Light spreads out at a ratio of 4 times the initial diameter of the aperture of the hole. It may look bright but it's intensity is diminished quite a bit the farther the object is from the hole making it. And light spots like this usually move fairly quickly across the scene.