The 2.8F I have examined is an earlier non-12/24 model with a Planar lens. The viewing hood is removable, but it does not open. This example lacks a focusing screen and mirror. The winding lever turns, but is very wobbly and is not connected to the counter or any internal mechanism. The focus, aperture and shutter speed controls do not turn, and the shutter release lock and the flash plug lock are frozen.
Inside, the back of the lens is not blacked out, and there is a pressure plate, but it has an "A" written on it in felt pen. It is missing the film tensioning rollers, the internal baffles and the film tension spring.
Inside the viewing hood.
The inside of the back.
With the back removed.