My oncid intergenerics get dappled sun for 9-10 hours a day. I figure if my Sharry Babies are freckling and the color of my leaves is a light green, they're getting enough. Not that I've ever rebloomed any, mind you, but I always take light recommendations with a big fat grain of salt and try to get just shy of burning every orchid I have. I figure that they'll always be happier with just about the most light they can tolerate without being damaged.