How to Use a Bahtinov Mask [TAIC Short]

As part of Ken Daly's original presentation on focusing, he shows us how to use a Bahtinov mask, including using a piece of software called Bahtinov Grabber to help.
Original video: ruclips.net/user/li...
www.theastroim...

[@adventuresofanamateurastro804]

When I use a bhatinov mask with my Dobson my 2 middle defraction spikes on each side will not center at the same time. One defraction spikes will be perfectly centered (doesn't matter which one's centered) but the other will be off no matter which one is centered . What could be the source of this issue?

[@proxima3286]

You probably have to collimate

[@wolpumba4099]

Amazing! I will try to print one. How well do I need to align the pattern with the optical axis? Would it make sense to create a phase mask so that more light is captured? Is that possible with my stereolithography printer?