Quote Originally Posted by snaggs
I really like the square format. Are they rangefinders? How do you focus?

No, not rangefinders...

You have two lenses of equal focal length, mounted on a movable plate one atop the other. The bottom lens has a shutter and is used to expose the film, the top lens is used to project an image on the groundglass (via a mirror) for focusing. Hence the name, Twin Lens Reflex.