finder sight in, eyepiece slop... grrrrr

[dreamlander]

I finally bought my first scope, Orion truss rod xx12g. I assembled it in my garage and took my sweet time going through the collimation process and as far as I can tell everything came out very well. I wanted to get the red dot finder aligned with the scope and it just so happened I have the view of an old car tire on a hillside 530m away that I can see from my garage. So I put the 28mm 2" ep in that came with the scope. I centered it and I could just make out the tire in the red dot sight, worked great actually. Then I decided I would put the 82 ES 30mm ep in. I noticed right away that it had more movement in the focuser so I made sure it was pushed in flush and as it is tapered where the set screws make contact I figured this is to help keep it flush and consistently in the same spot. This was a bit of a pain because the ep is so large it covers the thumbscrews make it difficult to even tighten them, but I got it. I go to look and now the tire is off center a bit. I also notice the edge of view is very distorted and the color looks bad. The 28mm Orion ep everthything looked great.

I find this incredibly annoying. A high precision instrument like this and there is major slop in the fit between the ep and focuser? I just don't get it. How hard is it to build something with tighter tolerances? I have plenty of rifle scopes and they all fit perfectly into the scope rings from all different manufacturers.

So what is the trick to get the ep consistently in the same place? and if one ep is a bit off from the next won't this not only throw off the red dot finder but the collimation as well because the ep won't be pointing directly at the secondary mirror? Also is it normal for the color and edge of the view to be distorted while looking at near objects in the ES 82 30mm ep?

I haven't got it out in the dark yet but I am already frustrated that I spent this kind of money and these tolerances are so bad. I hope the only answer isn't a better focuser, but if it is so be it.

Thanks for help in advance.

[rwilkey]

Hi dreamlander, if you have only used the 30mm ep during the day then you will not get satisfactory results, the ES82 excels at night-sky views and should do so in your new telescope.  The ep is also optimised for looking at distant objects such as those found in the night sky.  It will be useless on near objects.  Use the focuser carefully and make sure you get stars in focus properly.  Myself, I have invested in a stronger focuser to help support stability.

[dreamlander]

Thanks, this is what I suspected about the ep, your words are reassuring.

My real issue though is that the object being viewed is not dead center when switching ep's. It seems this would throw off the red dot alignment, star alignment  (goto), and even collimation when switching ep's. Am I over thinking it? 

4 days of work then a week off to get it out under the stars. So excited!

[brantuk]

When you align the red dot finder during the day - start with your longest fl eyepiece and get a distant object dead center in the eyepiece and finder. Then repeat using a shorter eyepiece - you will find it's off center so adjust as necessary. Then repeat again using shorter eyepieces till you get to the shortest one you use intend to use at night.

I use a zoom to do this but you can go with 25mm, then 15mm, then 12mm, and so on down to 8mm or 5mm depending on the scope and it's max useful magnification. Now when you observe at night you'll find all eyepiece switches will be dead center.  

[rwilkey]

Good advice from Kim above.  It is also quite common when moving from a low power ep to a higher power, that the object can by off-centre, in fact most people lose the object altogether during their first tries.  As with any stargazing, patience is as important as clear skies.  Take it easy and enjoy your sessions, a great learning experience!

[SonnyE]

I can fully empathize with you Dreamlander.

About all I can really offer is that when you change eyepieces, you are disturbing the sighting system. Like if you sighted in your rifle, then changed the scope. Put on a different scope, you'd have to sight in again, right. ;^)

I too, share your dismay with making a sizable investment, then feeling like you didn't get your monies worth. My learning curve was steep, but I figured it would be. I've been at my chosen path for ~11 months now. But I'm having fun. Around a month of that was warranty repair / replacement delays. (Talk about frustrations)

But, in time, things can be refined more and more. You will come to find the ways and means by which you will be able to rely on your new telescope to take you to those far, far, away places in the pictures. I couldn't find satisfaction with the available sighting devices either. I took my Tasco Red Dot sight out of my gun safe and began to figure out how to mount it for use. I did, and I did, and I loved the precision it afforded, and the minute settings to sight it in, and the 11 step brightness capabilities. So much so, when my aged Red Dot died, I tried a couple of other means but wound up getting a new Red Dot sight in the end. And mine is mounted on the stalk of my guide scope, I feel it holds its POA better.

Only so much can be achieved here on the Earth. You final tweaking and adjusting will come with stellar views. I read somewhere how the moon is your friend, how it can help with focusing and learning. And it can. But it is also very bright, you will find a Moon filter desirable. You'll need to find Polaris, and you'll need some bright stars to help with fine focusing... It's a long, and really, never ending learning curve.

Where you decide to go is entirely in your hands. Right now, look forward to Jupiter, and Pleiades is beautiful. As you get to know your telescope, the things like the eyepiece will melt away as you take in the breathtaking views. What till you get an eyeful of Orion's Nebula!

It's like learning to walk, just take one step at a time. And it isn't a rifle scope my friend, it is a time machine. Takes a little tweaking to get out there...

Less than 4 days to go now....

[dreamlander]

Wow, thanks for all the great advice and words of encouragement. I will try the stepping down the ep focal length thing. Along with the 30mm I have a tv 10mm Delos a tv 2x powermate to get started. 

An easy fix to the ep slopiness I can think of would be to get a different 2" ep holder part that threads into the Orion focuser. This one's id is way to big. Anyone know of such a piece? There are so many times I wish I had a lathe.

This place is great. So many people willing to help us newbs.

[Dave In Vermont]

I'll often notice that the accuracy of a finder (I use optical 50mm types) will change a little at night while observing and changing eyepieces. This is why I've come to love my GSO 8 X 50mm RACI's - I now have two of these. The GSO's have nylon set-screws, and they are kept, by nature, rather loosely holding the OTA. Some might find this a problem, but I've learned to enjoy this as it makes a slight change very easy to accomplish at night - without causing any shift in the view at the eyepiece.

I don't know if GSO consciously planned this or not. Either way, it makes small adjustments painless and easy.

That's my 2¢,

Dave

[John]

Hi,

Just a small point but are you using the 2" eyepiece adapter to fit the 2" eyepiece into the scope or are you putting the eyepiece directly into the drawtube of the scope ?

Like the Skywatcher scopes (made by the same manufacturer) the Orion XX12G uses a 1.25" adapter for 1.25" eyepieces and a 2" adapter for 2" eyepieces. The focusser drawtube itself is slightly more than 2" in diameter so a 2" eyepiece fitted without the adapter will be a sloppy fit.

 

 

[dreamlander]

Yes, I am using the 2" adapter if that is what you call it. It threads into the draw tube and has 2 set screws. I have a short one and an extended one in case I can't reach focus. The id on both is the problem, maybe I am exaggerating when I say much too large, but I thought this would be a much tighter fit than it is and didn't expect is to be that loose. This adapter is  the piece I thought might be easy to replace with something that has tighter tolerance.

 The 1.25" adapter goes into the 2" adapter.

[brantuk]

From the pictures it looks like you have low spec adaptors with just a screw to set the eyepiece in place. I prefer to use the brass compression ring type adaptors - but my 12" dob was supplied with the same as yours (when I had one). You do have a nice low profile 11:1 d/s focuser though which should be adequate with both 1.25" and 2" eyepieces. Ensure the 2" adaptor is screwed on tightly then you should only need to remove the 1.25" adaptor when using 2" eyepieces.

Some eyepieces (or cameras) may require a bit more back focus in order to achieve focus - in which case use the longer of the two adaptors. But otherwise stick with the short adaptor. You'll know if you need the longer one cos you won't get to the focus point with whatever eyepiece you're using at the time.

If you're still getting slop - take the 1.25" adaptor out and attach it to the eyepiece first - then slide it ensemble into the 2" adaptor. Then you won't have to fiddle under the eyepiece with the set screws - you'll have a bit more room under the eyepiece to reach the screws in the 2" holder. Sadly these scopes are sometimes made to a price and I think we all share your disappointment when we discover low quality parts. Hth

 

[John]

7 hours ago, dreamlander said:

Yes, I am using the 2" adapter if that is what you call it. It threads into the draw tube and has 2 set screws. I have a short one and an extended one in case I can't reach focus. The id on both is the problem, maybe I am exaggerating when I say much too large, but I thought this would be a much tighter fit than it is and didn't expect is to be that loose. This adapter is  the piece I thought might be easy to replace with something that has tighter tolerance.

 The 1.25" adapter goes into the 2" adapter.

I thought the 2" adapter is a push fit device with a flared bottom end - similar to the design of the 1.25" adapter ?

Maybe it's changed since I last owned one of these scopes though. The ones I've used in the past, though not the most precise devices, certainly were capable of holding 2" eyepieces in the centre of the optical axis.

 

[brantuk]

This one's a screw in adaptor John with a central 1.25" that fits in the middle of it like the WO adaptors (not the flanged one you're thinking of mate). I think they're keeping the in-focus short on this scope and providing an extension where extra back-focus is needed with the low profile focuser. At least that's what I make of the pics.

(My only gripe is it isn't a brass compression ring type like WO)