I just acquired a Speed Graphic (Pacemaker, I think) that is missing the viewing hood. Does the viewing hood serve any other purpose than making it easier to focus on the ground glass? Like preventing light from getting to the film? I'm thinking about getting the Polaroid back just to get started playing with this camera, to see if works ok.
Thanks for any input.

You are right - the collapsable hood on the back is not necessary for operation of the camera. In fact, you could operate the camera like a view camera, using a darkcloth. So, assuming the rangefinder is accurate, go ahead and use your camera. One purpose the hood does serve is to protect the ground glass, so be more careful than usual to protect it from scratches.

Thanks for your reply. I guess the rangefinder is working. I can faintly see some image movement when I turn the focusing knob. I'm going to play with it as a view camera for now. That's why I got it - a poor woman's view camera!!