184 replies to this topic

[Cenk]

Hi all, I collected my second hand Nexstar 6SE today. The corrector plate was very dirty (surprisingly on both sides) so I removed and cleaned it. The problem is, I didn't know that the orientation mattered (so I didn't make a note of it). What do I do ? Thanks.

[StarWars]

when ever I disassemble I mark with a magic marker for reference.

[Cenk]

what do I do ? Please help.

[Cenk]

Amazing support from the Celestron guys in the USA. Thank you very much guys. They helped me as much as they could, trying to talk me through it and said they would sort it out for me if I shipped it over there.

[spaceydee]

have you tried using it and seeing how it star tests after putting the scope back together?? have you re-assembled it already??

glad ot hear that Celestron was helpul!

[Cenk]

Hi Dee,
Yes they told me to try it a certain way around. So I cleaned it and put it back together. No chance of testing, as this is the UK and it is raining again. I don't really know how I would know if I tested it ? I have nothing to compare to ? Or is it easy ?

Thanks

[Tel]

Hi Cenk,

It sounds a really drastic step to have to ship your 'scope back to the US but from the limited search I made on the subject tonight, it looks very much as if somewhere along the line the corrector plate does need to be professionally realigned.

The only thing I would make sure of before taking this step, is to ask whether you've looked in detail (even perhaps under a magnifying glass), for any original marks made by Celestron technicians during the 'scope's assembly.

I did manage to locate an old 5" - 8" Celestron manual from the early seventies which describes the disassembly of the "C" plate (a feature which Celestron apparently removed from future manuals but which probably cross references at least in principle to your 6SE) but I don't think it will be of much help. Nevertheless you never know till you look.

http://www.company7....8manual1971.pdf

Failing that and rather than having to send it back to the US, couldn't David Hinds reseat it for you or alternatively, maybe Seeview Observatory in Cambridgeshire which also deals in Celestrons ?

www.seeviewo.org./

Hope it all works out to the good as soon as possible,
Best regards,
Tel

[Tel]

Hi Cenk,

Further to the above, I've just found that our member Bob T. seemed to have run into the same problem and posted under the title "Correction Plate Alignment" requesting help, (1st, Feb. 08) on the "Cats and Casses" forum (see his posting now on page 2).

He did receive some advice which you may find useful. If so, perhaps try a personal post to him to see how he's getting on with the solution to the problem ?

Hope this helps,
Best regards,
Tel

[Cenk]

Yes it is a bit of a long way. We tried to find these markings with the guys from Celestron on the phone. The unusual things was that my scope did not have the markings they expected. In face it had two and did not have a serial number where expected. The guy from Celestron was intrigued and offered and free clean and collimate if I send it to the USA and was very helpful. Which is more than I can say about D Hinds. I phoned them about cleaning the scope and got somebody very uninterested telling me, I am not sure what really. Something about £150 for this and £35 for that.
I rather pay £50 to ship it to the US.

[Tel]

Hi Cenk,

Well that does seem to be the best option in light of what you've just said.

Good luck and best regards,
Tel

[b1gred]

One thing I can tell you without fear of contradiction: IF you ship it back to Celestron, it will return to you BETTER than 'factory new'. They do OUTSTANDING work in that little lab of theirs.

[strgazr]

i agree with randy just send it back you won't be sorry celestron is great

[Cenk]

That's just what I thought. Thanks for the reassurance.

[Cenk]

I got a problem ! Shipping to the US is more that £130 for the OTA. I am not sure if I have to pay for shipping back. Assuming I now can't send it, can somebody please help me try to solving this one myself. I have a couple of questions:

1) How can I tell if the corrector plate is on the right way around.
2) I spent a long time trying to clean smudges out of the corrector plate, how can I tell if I damaged it's optical coatings.

This is really worrying me now, your help would be hugely appreciated.

Thanks in advance.

[strutsinaction]

This corrector plate removal link might be of help.

Good luck!

[rick rian]

Bummer ... You might want to try the Yahoo NexStar user group website, LINK and see what members there might say ...

Another place to visit might be Robert Pudlo's site where he walks you through the break down and and rebuild of a N5 OTA. Very easy to follow instructions with lots of photos of the pieces and parts ... Pudlo ... Clink on projects in the top menu and then NexStar5 tuneup, left menu, next page.

I hope this helps some ...

[Tel]

Hi Cenk,

To me, it looks very much from what I've now read within this thread plus all the links, that your choices are limited to either getting the plate reset professionally, at cost, (whether in the more expensive UK or paying an equivalent sum in just shipping to the USA) or resetting it yourself.

Should you choose the latter option, it then seems to me that from the literature searches so far conducted and displayed here, all mentioned procedures unfortunately lead back to the necessity to have marked the corrector before disassembly: the one and critical aspect you do not have.

Assuming further, that if the job were to be undertaken professionally, I suppose that would entail the use of special optical alignment equipment which would not be available to the amateur telescope constructor.

Thus if you do opt to carry out the work yourself, you will have to evaluate its quality by trial and error and in fact this was the advice given to Bob.T by Jeff (NeoDinian) on that "Cats and Cassies" forum. However, this is not to say that the necessary alignment can't be done.

That's as far my logic takes me, so I personally would try to reset it myself using perhaps an artificial star and then just rotate and test the plate until I gained its best position possible on this basis. If, however, I got no satisfactory result after trying this, I would then seek professional help but at least my vain attempts to reset the plate would have, up till that point, cost me nothing and who knows, I might strike lucky!

Purely my own view as to what I would do under the circumstances. You of course must decide your best next move.

Regards,
Tel

BTW, I would also have to assume that the secondary mirror had been in alignment prior to the removal of the plate because to rotate the plate AND try to adjust the secondary would really compound the problem.

Therefore, I would say, get the plate set as best you can and then and only then, tweak the secondary if, and only if, necessary.

[Cenk]

Tel,
Makes complete sense. Unfortunately, the secondary has also been adjusted already. I collimated the scope after the first removal of the plate. I don't think there is anywhere in the UK to align my plate. I don't believe D Hinds have the equipment for this either.
So my only choice is to try to do it myself.
What do you think to the cleaning and possible damaged caused ? Do you think its likely ?

[Tel]

HI Cenk,

Well of course I don't know how you cleaned the plate and with what material(s) but I guess you have to assume its OK unless you have any real doubt yourself. With what, for instance did you clean it ? I take it the point you are making is that if damaged, you'd be wasting your time aligning it ?

Assuming however that there is no damage, there's nothing you can do about the fact you've also adjusted the secondary. I think if you do attempt the work yourself, and as I said, that costs nothing more than your time and effort, you will have to live with fact that the plate or the secondary or both will be out of alignment when you start the work.

In this case, I personally would start by adjusting (rotating) the plate to a point where I could not improve on the image and then lock it in that position. I would then work on the secondary to see if I could attain something approaching the ideal.

As to whether "David Hinds" could do the job, I'd send them an email to find out and if so, at what cost and under what time scale. After all that costs nothing.

Meantime I'll take another look around and see if there's anything or anyone else out there in the UK who might help.

Best regards,
Tel

[Cenk]

Thanks Tel. After having had another lengthy telephone conversation with the technical guys at Celestron and sending them various photos of the plate the outcome is rather unexpected ! I am now told that certainly the Nexstar 6SE (I am not sure which others) is made in China and it is made in such a way that orientation does not matter ! Believe it or not, thats the word.

As far is damage is concerned, visually the only thing I noticed are 1 or 2 tiny little scratches and the rest are just very faint smudges. Am I correct in assuming that the effects of this should be fairly minimal ? I mostly used distilled water, lens cleaner and warm water to clean the plate. I used cotton wool buts, a very soft cloth, not sure what it is called but I had ordered it for the Plasma TV and some Kleenex tissues. Obviously somewhere along the way, during my rubbing and cleaning I managed to put those two scratches on. I hope they don't render the scope useless.

Thanks

[mclewis1]

I am now told that certainly the Nexstar 6SE (I am not sure which others) is made in China and it is made in such a way that orientation does not matter !

I've been told by multiple sources (including Celestron) that all the C6S OTAs with the exception of test or pre production models were/are made in China.

The orientation issue is very interesting. Perhaps the manufacturing process used in China is different enough to allow for this flexibility? If this does apply to all C6s it would certainly indicate lower cost manufacturing (less handling, less time to manufacture).

As far is damage is concerned, visually the only thing I noticed are 1 or 2 tiny little scratches and the rest are just very faint smudges. Am I correct in assuming that the effects of this should be fairly minimal ? ... Obviously somewhere along the way, during my rubbing and cleaning I managed to put those two scratches on. I hope they don't render the scope useless.

No, slight scratches and smudges won't affect the view. You need to have really really obvious debris to affect anything. There are even scopes around with visible chunks taken out of the primary mirror that serve up fantastic views.

Before you consider cleaning it again you might want to read up on the process a little, some additional suggestions are discussed here: CN Thread on cleaning SCT correctors


Put all this behind you and just enjoy that great scope.

[Cenk]

Thanks, that makes me feel a lot better. If the orientation does not matter, then surely it should be possible to buy a replacement plate ? I have asked the question. Just in case.

[Tel]

Hi Cenk,

I must admit that I find that one hard to believe that the plate requires no orientation (no pun intended !) - just because Celestron 'scopes (and they are) now built in China !

Nevertheless,-- I say "Go for it and assemble". After all you've nothing to lose. If as they say, it doesn't matter how the plate's positioned, then you've only got the misalignment of the secondary mirror to concern you which in turn, should only require a normal collimation.

As to the scratches, if they are minor ones they should make no difference to your 'scope's overall performance.

Next time around though, (and cleaning should be as infrequent as you can tolerate), I think this link explains it all :-

http://www.arksky.org/asoclean.htm

and as cleaning fluid, use "Optical Wonder" from Baader.

Super Stuff ! IMHO Second to none !

Good luck and best regards,
Tel

[Cenk]

Tel,

Thank you very much for your help with this one ! I don't really know enough about the workings of an SCT so can't comment on the feasibility of not requiring orientation. Who knows.

Cenk

[TheSheriff]

I hope your new info that the orientation is not important is correct, though I have my doubts. It would seem to me (no expertise here, just common sense) that the scope would have to be a completely different optical design for orientation to "all of a sudden" not matter, just because the scope was made in China versus the US.

Any chance you took a photo of your new scope before disassembly? specifically of the corrector? If so, you can blow that pic up and print it out. Use a straight edge and pencil on the photo to align various points on the secondary dust cap or collimation screws, corrector retainer, retainer screws and the edge of the tube.

Use those points and the straight edge, the more the better, to align the corrector. It may not be exact, but should be very, very close.

If you do not have such a photo, perhaps the previous owner?

LOL, Tel beat me to the "China" thing.