I am looking at a move to large format photography and while researching all that comes with it I was wondering if someone could tell me how photographers "proof" the shot before they start to shoot with the subject? I have seen Timothy Greenfield-Sanders use a what is essentially a large polaroid but I was wondering what people will do when the Polaroid is gone? It there a way to check light with a digital camera? I know a lot of photographers are using the Canon G9 to proof when using medium format because it has a hot shoe for the Pocket Wizard. Any help you can provide would be greatly appreciated.