Quote:Do you see any hint of a roof line-induced diffraction spike on bright objects? Have you looked down into the objective end with a close focus monocular or binocular to see if a roof line can be seen? (Explore the back end optics by adjusting the monocular's own focus.)
Quote:Jon,The lower of the two drawings shows immediately ahead if the eyepiece a two-reflection prism exactly like those found in 45 degree stereo microscopes. I should have envisaged this configuration. It is not a roof prism and therefore will not introduce a diffraction spike.These prisms tend to be a bit small, thus limiting the field of view. And one surface must be silvered/aluminized due to the steepness of the angle at which light strikes it. I don't much like them, although for f/5 and slower systems they do work well enough.