SCT optical/mechanical testing

matt · #1 24-07-2006, 05:36 PM

Anyone know of anyone in Australia who'd be equipped to carry out this sort of testing and repair/fixing?

For example, where would I send my 9.25 to have things like the orientation of the corrector/secondary checked or the mechanical side of the OTA (mirror housings etc) looked over?

Your help much appreciated

casstony · #2 24-07-2006, 06:37 PM

You might try Bintel - at least one of their people has trained at the Meade/Celestron factory. Does something about your images give you cause to worry?

Tony

matt · #3 24-07-2006, 06:42 PM

Thanks Tony

Bintel are not authorised Celestron dealers/repairers. The scope is currently under warranty.

acropolite (Phil) · #4 24-07-2006, 07:00 PM

I think York Optical are authorised Celestron dealers. [1ponders] had some fungus removed by Bintel on a C14 recently it may be worth checking this thread

matt · #5 24-07-2006, 07:09 PM

Phil.

I can't send it to Bintel. Period. Not yet.

They are not authorised Celestron dealers/repairers and therefore any work they might carry out would void my warranty. That would rule out the chance of a replacement should that be necessary.

The scope still has about 18 months warranty left.

At this stage it looks like York.

ausastronomer (John Bambury) · #6 24-07-2006, 07:26 PM

Matt,

What's wrong with the scope, or what do you think is wrong with it ?

Re Bintel:

I can appreciate that you are not able to go to them whilst the scope is under warranty, so at the moment that is not an option to you.

Something to keep in mind for future reference is that Bintel used to be a Celestron Dealer prior to switching to Meade. On top of that Don Whiteman, the head telescope technician at Bintel, actually worked for Celestron in the USA for a couple of years as a telescope technician. He is probably the best person in this country to pull apart a Meade or a Celestron SCT.

CS-John B

matt · #7 24-07-2006, 07:31 PM

Quote:

Originally Posted by ausastronomer

Something to keep in mind for future reference is that Bintel used to be a Celestron Dealer prior to switching to Meade. On top of that Don Whiteman, the head telescope technician at Bintel, actually worked for Celestron in the USA for a couple of years as a telescope technician. He is probably the best person in this country to pull apart a Meade or a Celestron SCT.

Something I'm very aware of John.

Don't want to go into detail as to what may or may not be wrong, at this stage. As much as I'd appreciate the many and varied diagnoses.

Cheers

casstony · #8 24-07-2006, 08:28 PM

Matt, you could entertain us all with collimation/star test images, photo's down the front of the tube, etc :-) I've been following the threads by Jerry Wise on the cloudynights forums - better than watching TV.

Tony

matt · #9 24-07-2006, 08:40 PM

Quote:

Originally Posted by casstony

Matt, you could entertain us all with collimation/star test images, photo's down the front of the tube, etc :-) I've been following the threads by Jerry Wise on the cloudynights forums - better than watching TV.

Tony

Already done the former

Not sure what a photo down the front of the tube would be worth other than a photo of a big shiny circle with a black tube poking out of it.

Sorry Tony. You'll have to find your entertainment elsewhere, I'm afraid.

Where is Ken ... by the way

Johno (John) · #10 24-07-2006, 09:05 PM

Matt,

Try asking your original dealer or Extravision. If it's under warranty they will have someone to deal with it.

matt · #11 24-07-2006, 09:10 PM

Johno

Have been speaking with Extravision today.

Fingers crossed everything will work itself out.

Gotta have that Plan B in place though...

matt · #12 31-07-2006, 04:10 PM

Here's a doozy.

What sort of equipment would you need to test the optics, particularly misalignment of the corrector and/or secondary, which might cause a soft focus in an SCT????

Rigel003 (Graeme) · #13 31-07-2006, 07:43 PM

Hi Matt,
I've had a Celestron Nexstar 11 for 3 years and have more recently bought an 11" CPC. I've also had initial misgivings about the optics in each case (I suppose it's natural when you spend a lot of money on a new telescope) - even tried an alternative tube assembly the 1st time. Compared with my 4" refractor, star images were not so crisp and at first I though the in and out of focus diffraction patterns seemed to suggest some form of spherical aberration.

What I've come to realize after lots of time with these optical tubes is that they are pretty consistent in quality. Star images and planetary performance aren't as crisp as in a premium refractor but they're ok and they compensate with much more aperture. Also, proper cool down is very important - vast difference in the star test when the optics are at ambient temperature and this can take hours unless you have some form of active cooling (I've just ordered the Lymax SCT cooler). Also need very steady atmospheric conditions for a sizable aperture to perform at its peak. Just some thoughts that might encourage you not to be too quick to judge yours if you're unhappy.

matt · #14 31-07-2006, 07:50 PM

Quote:

Originally Posted by Rigel003

Also, proper cool down is very important - vast difference in the star test when the optics are at ambient temperature and this can take hours unless you have some form of active cooling (I've just ordered the Lymax SCT cooler). Also need very steady atmospheric conditions for a sizable aperture to perform at its peak. Just some thoughts that might encourage you not to be too quick to judge yours if you're unhappy.

Yep. Am aware of all that and I've had the Lymax Cat Cooler for many weeks.

I've been struggling with this scope for about seven months, so my misgivings are not "too quick" in formation

I'm having it optically checked tomorrow. Will let you know whether your advice is on the money or whether I've had reason to doubt.

You never know Graham, it might have been rash to dismiss my apprehensions?

Rigel003 (Graeme) · #15 31-07-2006, 07:55 PM

Sounds like you've covered all the bases then. Good luck - I'll be interested to hear the results.

matt · #16 31-07-2006, 07:58 PM

Quote:

Originally Posted by matt

Here's a doozy.

What sort of equipment would you need to test the optics, particularly misalignment of the corrector and/or secondary, which might cause a soft focus in an SCT????

So.... back to the question currently before us?

Is there an optician in the house?

RAJAH235 · #17 31-07-2006, 08:56 PM

Matt, try DAW Optical Supplies. 10A Henley Road, Homebush West. 2140.
Ph..02-9764-1998. Wolfgang may be able to help.

L.
ps. Be careful if you 'Google'.

matt · #18 31-07-2006, 08:59 PM

Cheers Raj....

Merlin66 (Ken) · #19 01-08-2006, 08:16 AM

Using a Ronchi screen near focus position should show the misalignment and any other optical issues. Have you tried this??

casstony · #20 01-08-2006, 09:46 AM

Matt, at the risk of providing another answer you don't really need, checking for concentric circles from the front of the OTA should tell you whether the elements are all aligned on the same axis, or are you referring to their relative rotational positions to one another?

Hopefully one of the experts will become sufficiently tortured by our answers that they will chime in :-)