How do I remove the black cardboard cover form the end of the optical tube?
This cover does not get removed. This piece is actually a light baffle which prevents stray light from entering the back of the optical tube from behind the mirror. Removing this can allow the stray light to enter the tube and wash out your image. The main lens cap is removed from the opposite end of the tube, the side nearest the focuser and Star Pointer finderscope. The light from your target travels through this opening, bounces off the mirror at the bottom of the tube, and goes back up the tube to strike the secondary mirror, where it is redirected out the side of the tube to the eyepiece.
