Does anyone have any experience with photography of paintings and artwork that is behind glass? The gallery owner doesn't want to remove the paintings from the glass unless it is very necessary. These are being photographed in a room that has windows - not a perfectly controlled studio. Up to this point, I've been putting up cardboard in front of the windows to control most of the light - but sometimes the glass reflects the light bulb on the ceiling, etc. Perhaps it'd be easier to put up two umbrellas/flash @ 45 degree angle on either side or something? I read about this being done via google searches but it seems counterintuitive to me Any thoughts?