I own a Celestron C-150HD reflector, the discontinued 6 inch short tube with a spherical mirror and a built in Jones-Bird corrector on the secondary. I purchased this one as a challenge, and knew ahead of time that it is hard to get good performance out of these; but, it has been fun trying. This one still has issues on brighter targets, and it has trouble resolving images at magnifications higher then 100-150x. In short it's performance is worse then I would expect from an uncorrected 150mmx500mm short tube.
What I wanted to share with you is a odd effect that I have been noticing at the eyepiece. Even when collimated and properly focused, the scope tends to distort brighter targets like Jupiter, or Saturn; however, by moving further away from the plossl eyepiece (say 25-50mm - well beyond normal eye relief) the image seems to improve. Does anyone have experience with this, and can some explain why this seems to occur? I am wondering whether spherical mirrors favor one eyepiece design over another.
n2s
What I wanted to share with you is a odd effect that I have been noticing at the eyepiece. Even when collimated and properly focused, the scope tends to distort brighter targets like Jupiter, or Saturn; however, by moving further away from the plossl eyepiece (say 25-50mm - well beyond normal eye relief) the image seems to improve. Does anyone have experience with this, and can some explain why this seems to occur? I am wondering whether spherical mirrors favor one eyepiece design over another.
n2s