Last updated: 26 January 2006
Subject: ETX125PE Smartfinder parallax solution Sent: Wednesday, January 25, 2006 20:10:56 From: Deborah Pickett (firstname.lastname@example.org) I thought I'd share this little trick I applied to my Mum's ETX125PE Smartfinder to help her do alignment. She's a newbie to anything bigger than binoculars and was hoping that the PE's auto alignment feature would be hassle-free. But the scope still has to be aligned to two stars, and that was proving difficult because of the Smartfinder. I'd never used red dot finders before seeing the one on Mum's PE, and I wasn't very impressed with this one. The amount of parallax that you get between the dot and the firmament is pretty serious: moving your head can move red-dot/star alignment by a couple of degrees, which was enough to stop Mum from having any chance of finding the alignment star in the telescope eyepiece. I was pretty sure that the Smartfinder lens was correctly mounted, because it did go into the holder with that satisfying click. So to eliminate parallax and make sure that the eye is always in the same line behind the Smartfinder lens, I picked a point somewhere central on the Smartfinder lens, and drew a big crosshairs on it in black permanent pen. Now the routine to centre on an alignment star is: (a) align red dot with crosshairs by moving head; (b) align red dot + crosshairs with star by using AutoStar; (c) switch to eyepiece and spiral search for alignment star. I found that when all three (red dot, crosshairs, star) are aligned in the Smartfinder, the alignment star is in the supplied 26mm eyepiece's field of view, or at least close enough for spiral search to work. By doing this I was able to cut two-star alignment down to about a 60-second operation, and Mum was able to do it unassisted one night this week. This little tip might help some of the other less-experienced users of the PE and other so-called "automatic alignment" scopes to get to actual object viewing more quickly. Deborah Pickett Melbourne, Victoria, Australia
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