1965's Canon Pellix is a fairly standard 35mm SLR with one unique gimmick: the viewfinder doesn't black out when the shutter is fired! To manage this, The camera makes use of an ultra thin, semi-transparent pellicle mirror (hence, Pellix) that simultaneously transmits light to the film and to the finder. The mirror is fixed, so it doesn't flip up when the shutter is tripped, and you don't lose sight of your subject during the moment of exposure. The lack of mirror movement also limits vibrations during operation, which might help reduce camera shake a little bit. It's pretty weird when you've used SLR's your entire life, and you're used to the momentary blackout and mirror slap. At first it feels like the camera is broken!