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View Full Version here: : Lightbridge 12" Deluxe - Can't Focus Image!?


datorrey
27-08-2006, 10:42 PM
Help! I'm a beginner, and the proud but confused owner of a new Meade Lightbridge 12". The scope arrived badly out of collimation; only half of the primary mirror was visible in the secondary. I've followed the instructions and have it ready to use, but when put in an eyepiece and try to focus, I hit the outer limit of the drawtube's travel before the image is clear. If I then pull the eyepiece out of the drawtube by an inch or so, the image is just barely in focus.

I talked to Meade, and after making sure that I hadn't run the collimation bolts to their limit and shoved the primary mirror halfway up the tube, they told me that I need an "extender", which they will ship free of charge.

I'm a little puzzled by this. Isn't the focal point of a telescope a function of its length, and the positioning of the mirrors? Isn't getting the scope to form an image within the limits of the focuser a pretty basic thing? Should I return the scope and insist on one that doesn't need extra parts? I hate to return it if I don't have to, as I live in a remote part of the country. Getting to UPS is a three-day yak trip (well, OK, slight exaggeration for effect).

The guy on the phone muttered something vague about "it has something to do with the glass...", but wouldn't let me talk to the backroom guy who proposed the solution, so I really don't understand what's wrong.

I don't think that the collimation that I did is the culprit, as I've used very little of the travel of the collimation bolts on both mirrors. Any information would be appreciated. Thanks!

-daniel

janoskiss
27-08-2006, 11:29 PM
:welcome: to IIS Daniel!

Well you are correct in thinking that the focal plane of the telescope is fixed relative to the location of the primary mirror, but the other variable is the location of the focal plane of the eyepiece (EP) relative to the EP barrel. This can and will in general vary from EP to EP, which is why different EPs need different focuser travel.

That's pretty good service to get a barrel extension free of charge just because you happen to have EPs that don't play friendly with the scope.

datorrey
28-08-2006, 02:43 AM
Thanks for the welcome!

Actually, the eyepiece is the one that ships with the scope; that's why it confuses me that it doesn't work "out of the box".

Yes, I was pleasantly surprised at how helpful they were, and that they're sending a fix free of charge.

-daniel

iceman
28-08-2006, 06:06 AM
Do you have any other eyepieces you can try with it?

It is rather odd that the eyepiece they ship with the scope doesn't come to focus..

astronut
28-08-2006, 06:13 AM
:welcome: Daniel to IIS.and to the Lightbridge club. I had the same problem with my scope, the fix is simple. There are two screws on the underside of the focuser, the one nearer to the tube is the lock screw, if you unscrew it about half way out, this will allow the focuser to travel out about another 10mm this will allow the e/p to focus perfectly without having to pull the e/p partly out.:D

astrogeek
28-08-2006, 06:32 AM
Interesting. My 26mm that came with my 12" LB reaches focus with heaps of travel to spare. Why would they be different?

anildesilva
11-09-2006, 04:46 AM
Hello, I seem to have the same problem. I bought a new 8 inch lightbridge just yesterday. I put it together, and the collimation seemed to be true, so I did not have to manipulate the collimation screws. However, I have been unable to focus on anything with the 26 mm wide angle eypiece that the trussbridge came with. The only way to focus is to pull the eyepiece out till it precariously is barely in the tube. I did find that pulling out the drawtube beyond the limits of the focus knobs was a little helpful, but then the focus knobs can't find purchase on the drawtube to do anything. I guess I will call the store where I bought the telescope tomorrow and then call Meade maybe, but I can't say I'm thrilled at having to fix the telescope before I've used it even once.

astronut
11-09-2006, 05:45 AM
:welcome: Anildesilva to I.I.S. Check my earlier post (No 5) this will fix your problem. Cheers, John:D

ving
11-09-2006, 09:12 AM
welcome aboard our american friends :)
john (astronut) is our local lightbridge expert. i am sure his sugestion will fix your problem...

failing that, if you have an old barlow lens take the glass out of it and you have an extention tube :)

JimmyH155
11-09-2006, 01:15 PM
I have the same problem with the 26mm QX eyepiece. When I push it all the way in till it bottoms, then it wont reach focus. All I do though is to pull it out about 12mm , lock it in position and it works fine. All the other eyepieces - Hyperion, Plossl, Orthoscopics, work fine. I think it might be something to do with how far the primary mirror is screwed down towards the bottom of the scope. Maybe adjusting the mirror up or down and then re collimating, may work, but really it's no hassle to pull the EP out a bit. That eyepiece is GREAT - I love it:D ;)

spacezebra
11-09-2006, 06:17 PM
Hi there

And welcome to the IIS LB Club. I did not have an issue with the original focuser and 26mm. But I did change my focuser over to a MoonLite (personal preferences only) and focus is still sweet. I agree with Ving - John is the LB guru, great advice and excellent mods

Cheers Petra

nathang28
11-09-2006, 07:46 PM
This thread is destined to be "newbie" full it seems... so I don't feel too bad in increasing their number :)

I have been lurking for a long time here and am getting ready to purchase a LB 12" Deluxe in the next few weeks.

After extensive reading on eyepiece reviews/feedback here and elsewhere, I have settled upon the Orion Stratus as my first eyepiece choice (considering quality & price).

I am leaning towards the 17 or 13mm Orion Stratus eyepiece for my first addon, and my question is :- I have heard that some LB owners have had trouble obtaining focus with the Stratus eyepieces, especially in 2" mode, ie: the eyepiece inserted straight into the 2" barrel without a 1.25" adaptor.

Does anyone here have experience in using Stratus EP's with the LB, and are there any hints, tips or other "gotcha's"... :)

Hopefully I don't de-rail the original poster's thread, but given the topic is "can't focus image" I thought it was at least a related topic... :D

Thanks,

Nathan.

JethroB76
11-09-2006, 09:46 PM
At the risk of a thread hijack would anyone like to give some further comments on the supplied 26mm Meade eyepiece, as I have heard some very limited but varying views on it.
And like nathang I too would be interested in any experiences regarding Stratus eyepieces in the 12" LB, as I'm considering a similar purchase soon-ish.

astronut
12-09-2006, 08:34 AM
Hi Guys, I haven't used the Stratus e/p's, but it sounds like the same fix for the Meade e/p will fix it.
The Meade e/p has been praised by some and condemned by others.
It's a matter of personal preference, the last third of the e/p does produce some seagull views. This is not prominent and most of your viewing is done toward the centre anyway.
It's not a Nagler, but it is still a good general e/p.
I use it more than any other focal length. It has great wide views (70D,afov):D

JimmyH155
12-09-2006, 12:15 PM
The Meade supplied 26mm QX eyepiece which comes with the 12" LB De luxe is great. At first I didn't like it because it seemed fuzzy at the edges, but now that I have used it a bit, I think I was a bit out of focus. It is fantastic on clusters - try it out on M7 right overhead now. I call it my "Cluster Buster":lol: :D