They are, just have to consider that whatever lighting you have is adequate for their care. Also, have to keep in mind the potting material that the orchid is in. Due to constant mistings, the plant (depending on the potting material such as sphagnum moss) can drown because the potting media holds too much longer and doesn't get a chance to dry out.
I snipped the care sheet info for the oncidium from the American Orchid Society.