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Pages: 1 | 2 | (show all) brianb11213 Postmaster Reged: 02/25/09 Loc: 55.215N 6.554W Re: Corrector Plate Rotation--- Myth or Fact ? [Re: Midnight Dan]       #5328489 - 07/21/12 03:58 PM Edit   Reply   Quote Quick Reply   Quote: I think if I ever need to remove my corrector, I'll make every effort to put it back in the exact same location and orientation. It's simple enough to do, and whether it's actually needed or not, there certainly is no downside in doing so. A thoroughly sensible suggestion. It's just plain lazy not to mark items during disassembly so they can be put back the same way. If it does turn out to matter, and you haven't done it, you're either going to have to put up with seriously degraded performance or waste a hell of a lot of time trying to get the thing right by trial and error. Post Extras:       John Duchek Vendor Reged: 02/13/06 Loc: New Mexico & Missouri Re: Corrector Plate Rotation--- Myth or Fact ? [Re: Midnight Dan]       #5897533 - 06/02/13 10:13 AM Edit   Reply   Quote Quick Reply   Just took mine out from an old Celestron black tube 8" SCT. The orientation cannot be too precise given the marking was a magic marker about 1/4" wide. Hard to precisely align that. Anyway, the secondary is aligned to that mark, but one has to remove the secondary to see the magic marker (also 1/4" wide) on its back. Post Extras:       Geo. Carpal Tunnel Reged: 10/01/08 Loc: Upstate NY Re: Corrector Plate Rotation--- Myth or Fact ? [Re: John Duchek]       #5897668 - 06/02/13 11:33 AM Edit   Reply   Quote Quick Reply   Corrector orientation is not critical, but the secondary's is on the hand figured scopes. However, the corrector and secondary should be opically centered on the central axis of the primary. The best way to accomplish that is to note the placement and location of each schim and put it all back the way you found it, including the corrector. Post Extras:       sonny.barile sage Reged: 10/19/10 Loc: In the middle of the glow. Re: Corrector Plate Rotation--- Myth or Fact ? [Re: Geo.]       #5898520 - 06/02/13 09:18 PM Edit   Reply   Quote Quick Reply   I am just guessing but maybe the thickness of the corrector varies based on grinding and therefore the rotation makes a difference because if rotated it would no longer be parallel to the primary? Post Extras:       Tel Postmaster Reged: 03/31/06 Loc: Wallingford England Re: Corrector Plate Rotation--- Myth or Fact ? [Re: sonny.barile]       #5899029 - 06/03/13 04:36 AM Edit   Reply   Quote Quick Reply   My word ! I thought this one had been put to bed ! I'm still unconvinced that there is any need to pay extreme attention to the orientation of the corrector plate/secondary mirror particularly since a colleague and I successfully removed, cleaned and replaced this unit on a 8SE just a few months ago. If one reviews earlier descriptions of this task, these refer to the use of cork shims and paper spacers which were all apparently necessary to effect precise optical alignment of the corrector plate and secondary mirror with its primary, making the operation a somewhat daunting task and thus not to be undertaken lightly. This, I would guess, applied to those Celestron SCTs which were produced in the USA: like my Nexstar 8i. However, (and (Mike Swanson's Nexstar website describes this), individual cork shimming or paper spacing is no longer used, as we indeed found when we removed my colleague's 8SE's corrector plate. Apart from the retaining ring, a simple, one piece rubber gasket is now used. I would therefore srill submit that accurate replacement/ alignment of the corrector plate and secondary on these Chinese, mass produced SCTs is no longer regarded as sensitive as perhaps it once was and that, as we proved, a little collimation, ("when and if"), after reassembly is all that is/may be required. Again, just one guy's personal opinion but at least based on practice. Best regards, Tel Post Extras:       Pages: 1 | 2 | (show all)

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