Users of reflecting telescopes that have vane-supported secondary mirrors are well aware of the
connection between the vanes and the diffraction spikes that appear extending from images in the eyepiece. Few, however, understand
why the spikes occur or what the geometric relationship is between the spikes and the vanes. Even fewer understand the relationship
between an obscuring shape and the diffraction pattern resulting at the focus. The purpose of this paper is to make an explanation
without delving into the mathematics of diffraction theory. The diagram above will provide assistance, and we’ll begin
there naming parts.
All about curved spiders and there search light scatter effects.
This hack saw type has OFF CENTER spiders that will cause terrible diffraction effects.
Here is a study on telescope diffraction effects.