Just from it being about half the height of his head, it's something like a 6.5x9cm, or 9x12cm at most, and I think it's a strut-folding camera with a focal-plane shutter, like a Deckrullo-Nettel or the equivalent from another maker. What we're seeing is the front plate, out on a bellows in front of a wooden box body. On top of the body you can see a knob, which probably winds the focal-plane shutter. On the front plate, the bright item at top right (our top right; remember our view of the camera is reversed left-right in a mirrror)) is the screw that tightens the front rise adjustment. To the left (again, our left) of the front plate you can see the ends of the struts.
Here's the Deckrullo-Nettel, and Ernemann's version of the same thing: