Plans for a 4x5 astrograph box camera.
Framework of camera 1/2" Plywood inner painted flat black with velvet ribbon light traps.
Front with current 150mm F5.6 Lens on lensboard.
Back Ronchi Screen 100LPI printed on transparency film over glass.
Ensure that film plane and the glass are in the same spot. Focus with Ronchi Screen, then check the focus with B&W film.
Focus travel +/- 1".