Posts Made By: Brian Risley

This is the first f20 shot.

Here is another f10 shot I missed processing earlier.

Nice image.
When did m101 get in the solar system?
Brian

Don,

Uncle Rod Mollise is a good source. His used SCT guide at :
http://skywatch.brainiac.com/sct-user/usedSCT.PDF is a good source of information on the different models.

As for some disassembly and other information:
http://ngc1514.com/Celestron/celestron.htm
Has a C-8 dissassembly. This is the Orange Tube model, but the optic tube hasn't changed significantly between models. The drive bases have differed.

As for C-11's, look at these pages:

http://www.laughton.com/paul/rfo/c11-disasm.html
http://www.rothritter.com/C11_Project/
http://astroshed.com/observatory/c11saga/c11saga.htm
http://easyweb.easynet.co.uk/~chrish/lx_flop.htm
http://www.dd1us.de/Downloads/CNGPS%2011%20Removal%20and%20Replacement%20of%20Azimuth%20Slip%20Joint%20part%201.pdf

Brian Risley

You may have issues reseating and aligning c-8 optics. I know, I have one I had to have recoated and I am finding it a job to get this aligned. For all the coaters I know, you must have your mirrors off of any metal holders. For a C-8 that means removing the primary from it holder (it is glued in with RTV besides the cork rimmed retaining ring) and removing the secondary from its support. Once coated, the primary has to be replaced so the optical axis is centered. This is not an easy job! You also need to replace the secondary holder in the exact location and orientation.

My recommendation is check with Celestron!

Brian

That is the f5 telecompressor. Celestron and Orion both carried these. (Don't know if Meade ever made any.) These were common prior to the f6.3 reducer/corrector. Celestron originally sold them for photography, but later married them with a diagonal and a shorter tube (shorter than the standard T adapter they sold) and sold them as a visual f5 adapter (Late 70's, early 80s). With a 35mm film plane, these produced a circular image with some curvature at the edge. The reducer/corrector was developed to increase the field and provide better edge correction. When used with the original Celestron off axis guider, an extension tube was often needed as these units went after the guide pickoff prism and the focus change required that the eyepiece be placed about 1.5" further out.

Yeah, I would prefer clouds/rain over negative temps!
Brian

Carl,

You don't need a special tool to collimate the Celestron 8" Schmidt Cass scopes. There are 3 screws located on the front of the secondary holder that do this. They may be covered by a plastic cover that should pop off. The process of actually collimating has been covered on several web sites.
http://ngc1514.com/Celestron/collimate.htm
http://legault.club.fr/collim.html

Many people like replacing the screws with Bob's Knobs. There is information on this site about collimation too: http://www.bobsknobs.com

Uncle Rod has instructions at:
http://skywatch.brainiac.com/sct-user/collimation.pdf

Another site that may provide some insight is: http://home.att.net/~starastronomy/Astrophotos/Articles/SCT-Collimation/sct-collimation.html

Brent Maynard has some nice shots of what you see during collimation at:
http://www.astronomy.the-maynards.us/collimation.htm

Unless you bang the scope around, it will usually hold collimation quite well. Final collimation tweaks can usually only take place under good steady seeing where the airy disk is visible clearly.
Some people use daylight collimation using a reflective object (Christmas ornament, Ball Bearing, telephone insulator located a good distance off to do collimation during the daytime and to avoid waiting for clear seeing.
Floyd Blue has some discussions in Equipment Talk about an artifical star he built to do a similar function.

Actual star test using the airy disk with a cooled down scope is still the absolute best.

Note that using a diagonal may not align you perfectly. If you always use a diagonal, then you may want to do it with it in, but do rotate it around to see if this changes the image. If so, you may want to look at getting the diagonal collimated or replaced.

Good luck and clear seeing,

Brian Risley

Michael,
This is for a 1972 model, they have changed the assembly since then. Also, I have previously been told that they do not have the parts for the older scopes.

Leadscrew is probably better, but since I have to have the corresponding piece also machined, as it is stripped, I will take whatever I can. Unfortunately, your link does not have pricing. Thank you for finding it though.

Brian.

Nice shots Jim.

I was imaging it at the same time, but my sky conditions weren't that great. I have bare hints of the storm on my shots.
Gotta work out my brightness, using a laptop LCD screen gives a false impression of the brightness of the image. I find it is too dark and playing with brightness/contrast in registax also increases the background.
C-8 Ultima 2x Barlow, Toucam 740.