I find it hard to get lighting correct also.
it must be the hardest thing to do in photography!
I think the problem you have here is that the paper is so white and her hair is so dark, that you aren't going to be able to expose both properly.
it's just like taking a picture of a shadowed house in the middle of the day-you'll either get the sky perfectly exposed, but the house will be a silhouette or the other way round.
The only way I can see round your problem would be to have another light shining on her hair, whether that be an extra flash or a reflector reflecting the sunlight there.
anyway, that's what I think, but i'm certainly no expert :-) |