Collimation

[BABFB]

Need some help. I have a DS-2114 Telescope, and it just does not seem to focus as i would expect. I was looking at Jupiter last night and it will not focus in detail. Jupiter was just a fuzzy ball with no detail. Could not see equitarial bands or anything. Just a fuzzy ball of light with a few small dots of light of the other moons.
Is that the way this scope is, or is it a collimation problem? I know that is a hard question to answer, but any advice would be appreciated. Thanks, Burt

[swood333]

when you look at stars do they appear to have small tails like comets.. .. if so it's it's collimatin.. if not it's more than likely scope, or i'd say...

if it is collimation I would even start to adjust it till you read up on star testing... i've found it's the only way I can even remotly get my short tube 20130 to produce anywhere a decent image....

any questions shoot me a line back..

[BABFB]

Hello swood333. I have in the past asked the same question in this forum, and got a lot of help. You might be able to look it up under babfb. I have read it more than once, and it is a little overwhelming. Being a 20 year novice. I am on my third scope, but I really don't know the optical mechanics. so I am a little weary of trying to make any adjustments. Living in the middle of nowhere the closest Meade Dealer is at least an hour drive away. I will look up star testing and see what I can find out. I have thought my focus problem could be the temperature differentiation from indoors to outdoors, and maybe my scope had not equalized with outdoors. Gonna try it tonight, but the sky does not look like it will cooperate, but I will set it up at halftime of the Longhorn game. That should be enough time for temps to equalize. Thanks for your response. Burt 

[swood333]

here's a web site that really breaks it down very simply...

http://www.astunit.com/tutorials/startest.htm

i actually used a "false star" that I made from one of those multi LED flashlights.. just put 2 layers of black tape over it and poked a hole in it with a needle had to experiment with the size of the hole a bit to get a good equivalant to a "star" but I was sitting in my living room and had the flash light sitting in my kitchen and did in 15 min what I had been messing around with for weeks trying to do... the next night the views were great... best the scopes produced.. still mind you  the ds series IS a begineer series of scopes I wouldn't imagine you're gonna get refractor quality images... you can do a general search for info on "star testing a telescope" and after pilfering through a bunch of sales sites you'll find several sites that lay it out pretty clearly.. once you get it in tune it's not to hard to maintain...

as part of my general set up now when I'm viewing I just go in and out of focus on the second star during the star anignment and all it takes ia few light tweaks on the lock screws BY HAND, and they're even plain socket head screws.. so it  really doesn't take much to give you a "bad" image..

hope this helps...

[BABFB]

Thnks for the help swood. I will try that. I am just scared of moving things and making it worse. Kinda like a NASCAR driver. make an adjustment, and you adjusted too much. hehe He goes to the back. I don't want to make things worse than they are. Or, I could be expecting too much. Need to put a good MEADE on lay-away. hehe Thanks again. BABFB, Burt

[MistrBadgr]

If it seems like your focusing is headed in the right direction and you just run out of room in the focuser, it could be that the mirror has a different focal length than it is supposed to.  I think the telstar version is more prone to this.  I had one that ended up having a focal length an inch too short.  I shortened the rear of the tube an inch, did some other things along the way, and it works great.  The mirror had been ground to a perfect spherical shape, just an inch too short on the focal length.  I had it refigured to a parabaloid, realuminized, and changed out the focuser to get the eyepiece closer to the tube.  It is not a beginner's scope any more.

If your scope is in warranty, and you just cannot get it to focus clearly, I would see about a replacement.  You can call the Meade for that, I believe.  I worked with them a number of years ago on a replacement mount.  They sent me a replacement, I loaded a defective unit back in the box, and had UPS come and pick it up.  Meade paid for shipping both ways.  I am not sure how the system works now.  But, it would be worth a try if the scope just will not focus.

Hope this helps,

Bill Steen

[swood333]

I found this short website that covers collimation via a "startesting" methodology pretty simply... hopefully it'll be informitive...

http://legault.perso.sfr.fr/collim.html


i still suggest making or buying a "false star"... it does simpify things...

[MistrBadgr]

I read enough to know this is a good site for an explanation.

Thanks!

Bill Steen

[BABFB]

Just thought I would let you guys know that I bit the bullet and tried to collimate my scope after almost a year. Happy to inform you that it worked! The image is really clear, and I am very tempted to tweek it a bit more, but we know what will happen if I do that. I will lose it and never get it back. Don't know if I
understand what I did, or just a LUCKY Shot. None the less, I have never had a clear view like this. Can't wait for next weekend weather permitting. Thanks for the advice guys.

[BABFB]

To whom it may concern, I stayed up all night last night after tweeking my screws for collimation. Jupiter looked O.K., but the stars have a bunch of little spikes coming off of them. Looks like a Trident. Stayed up to see Saturn and that was a total disappointment. Well, I have totally taken my scope apart, screwed all the Primary mirror screws out to a base point. Spent 5 hours turning screws today. The concentric ring you are supposed to see in the draw tube at the Spider Frame looks like a Waining, or Waxing moon. Just a little out of round on one side. Do you more knowledgable fellas think that is close enough? Gonna try it out tonight to see what I have done to my scope.

Need some Luck,
Burt

[MistrBadgr]

Burt,

You will normally have three spikes coming off stars, due to the straight legs of the spider.  They will be spaced evenly around the defraction disk of the star.  Any more than that, then there is probably something out of alignment.

Normally, when I pick up a new (to me) scope, I do the following:

1.  I make sure the focuser is perpendicular to the telescope tube.  At this point, you may not want to get into that.

2.  I use some spanners and a little ruler with 1/50 inch marks to make sure the secondary mirror is centered in the main tube.  If you really want to get technical, there can be an offset that should be put in, but for starters, just make sure it is centered by making sure the distance from the edge of the plastic mirror holder to the inside of the tube is the same all the way around.  If it is a little closer to the tube away from the focuser, that is OK.

3.  Make yourself a peep site by taking an old plastic film can, cut the bottom out of it and punch a small hole in the very center of the lid, just barely big enough to look through.  Put the lid on the can.  Put masking tape around the can until it fits snuggly in the focuser.  Look through the peep site and see if the secondary mirror looks centered.  The mirror should look centered in the direction from side to side of the main optical tube.  If not, then the focuser may not be angled correctly.  Adjust the scres  on the secondary mirror to move it up and down the tube until it looks centered.

4.  After all the above is done, look into the open end of the scope from enough of a distance to line up the spider legs with their image in the primary mirror.  When you get that image, look and see where the secondary mirror looks compared to the main tube.  If it looks centered, then you are ok.  If not, experiment with changes in the primary mirror screws until the secondary mirror looks centered when the spider legs are lined up with their images.

5.  Then, look through the peep site and adjust the secondary mirror until the image of the primary mirror looks centered.

6.  Go back and repeat step 3, then continue to 4, then back to 5 until you do not have to make any more adjustments.

7.  Take the scope out at night and line it up on a fairly bright star and use your 9 or 9.7 mm eyepiece.  Centere the star in the firld of view.  Move the focuser to take the star out of focus a little.  You should see a center white disk with rings around it.  If it is all centered, you should be in good shape.

This is a very crude discription, but it should get you close enough to work reasonably well.

Hope this helps,

Bill Steen

[BABFB]

It helps out tremendously Bill. I REALLY appreciate all your Gracious help. Just looked through my scope.
In the Setup Capella, and Vega had a few flares off to one side. I am definately in the ball park again.
Jupiter looks pretty good, but I think it could be better. That line of thinking is what got me where I am now. Can't leave well enough alone. But I think I am back in a resonable adjustment area. Could it be that
I am just EXPECTING TOO much from my Ds-2114? That is probably the biggest problem.
  I will take your advice to Heart Bill. Thanks again. Give me something to do till next weekend.

Thanks Bill, very, very much.
Burt

[MistrBadgr]

Burt,

If you run across a book called Star Testing Astronomical Telescopes by Harold Richard Suiter, published byWillmann-Bell, it will tell you about all you can handle related to colimation, etc.  I will not kid you into thinking I understand everything he says in the book.  A lot of it simply blows past me.  But, there is a lot in the book that has helped me with my telescopes.

As far as your 2114 goes, I thought at one time that you could not expect much out of them.  I am sure you cannot get as much in either contrast or definition as with a real f/8 newtonian.  The 2114 has an f/4 spherical mirror with a 2.2x barlow that has spherical correction in it.

I took one that had a mirror with a focal length an inch short of what it was supposed to be, talked someone into parabolizing it, reworked everything in the scope including a curved vane spider, a better focuser, light trap material, a 1/20th wave secondary mirror, and then used a 2.2x barlow with parabolic correction in it.  My best view of Saturn with it was with a 6mm othoscopic eyepiece.  With averted vision I could see at least three of the minor moons as well as Titan.  I could not quite make out the Cassini division in any real sense, which I could do with an F/8 4.5 inch scope that I had made the same modifications to. 

The f/3.8 (rather than f/4) mirror tested out to be slightly better than 1/8th wave, while the f/8 mirror was somewhere around 1/15th.  The common industry standard for lower level Newtonians is something like 1/3rd wave.  The human eye is supposed to be limited to detecting error down to 1/4 wave.  I think the brain can overcome that limitation somewhat and can allow you to be a little more discerning at least at a subjective level.

Because of my experience with my scope, I cannot truly say that you cannot expect much out of a 2114.  It depends a lot on how well you can collimate it.  Having the booster lens in the way is a pain, but tenacity can prevail in the long run. A mediocre scope with a superior collimation will out perform a superior scope with a mediocre collimation.

I think with some TLC, your scope can see a lot of things and do a lot of science.  I expect its magnification limit will probably be around 140x without a lot of upgrading.  With that said, you can have a lot of fun with it.

Bill

[BABFB]

MistrBadgr, can you explain the f/ specification? If I understand what I have read it has something to
do with the focal length in relation to the diameter of the mirror. If that is so, "What does it really mean?"
I'm sure it is pretty hard to explain in laymons terms so don't feel bad if you can't explain it to my feeble
mind. I am just trying to understand my scope better.
Thanks,
Burt

[BABFB]

MistrBadgr, I just found a pretty detailed explanation of f/ or focal length. Think I have a handle on it now.
Thanks just the same.
Burt