To demonstrate that acceptable images of birds can be taken through double pane glass, I shot some images of birds near my feeder to make this quick composite. A flash unit was used because the feeder is in shade. One nice thing about digital cameras is one can change ISO settings as light levels change. To take images through glass windows you have to keep the front of the lens as close to the window as possible to reduce interior reflections. Holding the lens perpendicular to the glass minimizes distortions due to the window glass. A fast shutter speed or flash allows one to stop action.