By the way, Richard.
The fastar models (if you are going to use fastar) are CRITICALLY
dependant on the alignment of the corrector to the primary. The problem
you mention doesnt affect anything through the rear (normal) that uses the
secondary but for fastar it counts double.
The current fix is to drill and tap through the ring around the corrector
in 3 places and use screws to precisely line up the corrector. It helps
if you find some nylon tipped set screws (McMaster Carr has them).
The vendor problem is recent and does not affect the older ones. I dont
know what kind of C14 that Shade has.
CI (I am led to believe - havent seen one) is putting the adjustment
screws in some of the scopes. But the word is that any SCT using fastar
can benefit from the mod.
Again, this does NOT apply if you have a fastar scope and are NOT using
the fastar setup.
---------
Phil Chambers [ptchamb@No-Spam] (S.F. Bay Area - Calif. USA)
On Sun, 28 Sep 2003, Richard Crisp wrote:
>
> ----- Original Message -----
> From: "Mike J. Shade" <mshade@No-Spam>
> To: <sf-bay-tac@No-Spam>
> Sent: Sunday, September 28, 2003 4:19 PM
> Subject: [TAC] (OT) C14 secondary alignment
>
>
> > what is the alignment for the secondary for a C-14? Don't the numbers
> on
> > the front of the secondary "point" about to the Celestron sticker on the
> > side of the OTA, more or less?
>
> The corrector plate has a serial number that aligns with the celestron
> sticker on the side. You cannot see the serial number unless you remove the
> retaining ring.
>
> The FASTAR secondary has a slot where the alignment pin is inserted. That
> slot aligns with the same celestron decal, which is the one on the right
> side of the scope as you are looking at the visual back.
>
>
>
> >
> > Amount of variation allowable?
>
> Just get it close.
>
>
> >
> > Also, what is the tension on the retaining ring for the secondary? It
> > should be turnable with little hand pressure not really not tight,
> correct?
>
> If you make it too tight the entire FASTAR receiver will rotate in the
> corrector plate. My C14 also has a bit of lateral play in the FASTAR
> receiver. It is a really good idea to remove the fastar secondary, look down
> the front of the scope and make sure that receiver is properly concentric
> with the primary mirror. Mine needs to be shoved all the way to one side.
>
> Out of two C14's I am intimately familar with, both have their optical axis
> offset slightly from the mechanical axis. I believe the baffle tube is not
> perfectly perpendicular to the rear casting and have learned that Celestron
> had a QA problem with their subcontractor that did the machine work for
> them.
>
> Mine works great once I learned all this stuff and aligned it properly. I
> also made and installed mirror locks to further improve it for imaging,
> which is all I use mine for.
>
> http://www.rdcrisp.darkhorizons.org/mirror_locks_to_solve_c14_page.htm
>
> When I added the Dichroic Beam Splitter to permit the use of an AO7, it
> really kicks butt:
> http://www.rdcrisp.darkhorizons.org/dichroic_beam_splitter_page.htm
>
> http://www.rdcrisp.darkhorizons.org/trapezium_sii_page.htm
>
> Hope this helps, Mike.
> Richard
>
>