I use a scope I built for testing all my mirrors. I tend to make f/6 and longer mirrors and an 18"f/6 is a pretty long test. 216"..so a scope is nice. I tested an 8"f/4 yesterday and its 64" test is pretty close so no scope was needed.

Hey..I have a question...some folks are setting their KE so it splits the light exiting the LED before it strikes the mirror. Does it make much difference if you split the light after it hits the mirror and is returning to the tester?

Rob(I don't seam to be having any trouble with my setup)