Hi Karen(posted 9028 days ago)I'm no professional, but I think you're essentially referring to the scale of values from pure black to pure white that can be produced in a B&W image. This is best described by Ansel Adams in his book The Negative, particularly in the chapter "The Zone System" (I think it was chapter four- yes this is a bible!). This is a deceptively complex topic. I've read much about it but Ansel explains it best.
To answer your other thread above about the best camera for architecture, there's really no single best camera in general- that's a subjective question. For architecture you can go several ways. A 35mm SLR may be used with a PC (perspective control) lens that allows you to prevent distortion that would otherwise occur when your camera is angled such that the film plane is not parallel with the plane of your subject i.e. a wall or beam. The best quality result for this type of photography is probably best with a view camera that is set up on a rail that allows perspective control such that the film plane position is adjustable independently of the lens position.