Diagonal with no reflective surface?Posted By Brad Bassett |
I purchased a used Celestron eyepiece turret a couple of months ago. I noticed that it produces a searchlight beam of scatter in two opposite directions. So I took it apart to see if I could tell anything. I noticed a smear or smudge that was not on either exposed surface of the prism, looking like it was on the reflective surface, which mystified me. I thought maybe it was a defect in the aluminizing. So I took it apart further and to my utter surprise found that the reflective surface of the prism was completely clear. There is no metal on it at all. There is only a piece of black paper behind it held in place by a plastic wedge. I cleaned the surface anyway to see if it made any difference. It did reduce the scatter slightly, but not enough to really be to my liking. So I'm really surprised that this works as well as it does, it's better than my old Celestron mirror diagonal for scatter and it's equal in light throughput. I can see the pattern in the paper slightly when looking through the diagonal at a certain angle. Could this be the cause of the scatter beams? Would a darker black backing help? Should I try using charcoal on the paper, or would this getting on the prism be a problem? Wouldn't it be much better with some aluminizing or silver on the reflecting surface? Any other thoughts?
Thanks,
Brad
Thanks,
Brad