Bahtinov focus mask for telescopes with aperture of 89mm to 165mm

Decent Bahtinov mask

( 4 / 5 )

Gives decent view of the diffraction pattern when targeting a star. It does what it is meant to do.

My only concern is the material its made from. It seems like its laser cut from a sheet of plastic and it has some flexibility to it. Which can be both good and bad. If you don't have a solid storage location it may just break on you.