Bahtinov mask for Nikon 200-500mm f5.6

A Bahtinov mask add-on for my Nikon 200-500mm f5.6 diffraction spike generator meant to assist with achieving perfect focus in astrophotos. It uses the same mounting ring to attach to the front of the lens hood. 

Print in black filament to reduce reflections that can degrade the contrast of astrophotos. Sand the inside of the mount until it fits smoothly but snugly with the mounting ring.