Collimation - My Arch Nemesis

[pevsfreedom]

So I've had a 10" dob for a couple of months now, and haven't been able to use it successfully at all. 

I try to star-hop after collimating and use a 30mm EP and the stars are blurry, can barely tell what I'm looking at. 

The scope came with a laser collimator. That one was junk and they sent me another one, which I'm afraid might also be junk, but I'll give it the benefit of the doubt. 

1) I've read that laser collimators can be tricky. I've heard they are good for the 2nd mirror to center on the 'dot' on the primary? Am I correct in that regard?

I've also read that to use a laser successfully on the primary, you should use a barlowed laser (I have this S&T article for reference:  https://www.cameraconcepts.com/barlowed%20laser%20collimation.pdf )

2) Can I use the 'barlow' method with an adapter? I have a 2" focuser, and a 2" barlow, and a 2>1.25" adapter and a 1.25" laser. Would the 'chain' go barlow into focuser with the adapter and laser into the adapter? Would that be acceptable?

3) The article states you need some kind of 'cap' to use with the barlow. That part in the article didn't really make sense to me as I'm not much of a DiY'er. Can anyone elaborate on what I need to use to make the barlow work correctly with the laser?

Am I missing anything else here? 

Thanks

[Helite]

I have never seen a scope that far out of collimation that it was unusable and unable to focus on anything. Why did you have to do the collimation initially, was the scope new or second hand?

I think laser collimators get a bad rap but I have had no issue with mine, once I have aligned the laser to ensure it is itself collimated it works fine, I have backed this up by using a combination tool to check everything was aligned.

Maybe be worth checking your laser by making a V block and rotating it and making sure it is aligned, there is guides in the DIY pages for this if I remember correctly.

I have never used the barlow method with the laser so cant comment on that sorry. It may be worth you buying a cheap combination tool to use with the laser or instead of it if you thing you are that far out of alignment it is causing everything to be blurred. 

[pevsfreedom]

It was new but I thought you had to collimate a dob every time you use it. I have to move it a lot and just checking it initially it was off with the laser. I can focus on things like Jupiter sort of but it gives me a bad headache. Stars are a blur and won't come into focus really. 

[Big Jim Slade]

Unless it's badly out of whack, you should be able to focus on something (to a standard  good enough for the human eye) - collimation should be about fine tuning the whole field and getting the sharpest stars possible. I would expect a Dob or Newt to hold collimation well enough for non-OCD visual. Unless you are dragging it down a flight of stairs every night of course. 

I could be wrong but it sound more like you are lacking an extension tube to reach focus with eyepiece you've chosen. 

[pevsfreedom]

Unless it's badly out of whack, you should be able to focus on something (to a standard  good enough for the human eye) - collimation should be about fine tuning the whole field and getting the sharpest stars possible. I would expect a Dob or Newt to hold collimation well enough for non-OCD visual. Unless you are dragging it down a flight of stairs every night of course. 

I could be wrong but it sound more like you are lacking an extension tube to reach focus with eyepiece you've chosen. 

Speaking of which, I have an extension tube, and have no idea when I should be using it. Could that be the problem? Last I remember I did NOT use it when trying to star hop (which was a few weeks ago, I got really upset because I couldn't find my way around things I've looked at a hundred times in binoculars). Do I wanna use the extension tube every time I use the 2" 30mm EP? 

[Jason D]

Using an adapter with a 2" barlow is fine for the barlowed laser method.

As "Big Jim Slade" mentioned, are you sure you are not running out of focus travel? That is, do you rack the drawtube all the way in or out and still can't reach focus?

At what you consider to be the focus point, do stars look like comets or do they look like donuts?

Jason

[kens]

That depends on the scope so the only way to know for sure is to try it out.

So first of all set up in daylight and point the scope at a distant landmark. CAUTION - Don't point anywhere near the sun!

Wind the focusser in as far as it will go.

Slowly wind it out till the distant object comes into focus.

If you still can't get it into focus with focusser all the way out then wind it all the way back in, attach the extension tube and start again.

If it still does not come to a focus it's going to get trickier so try the above first and report back.

[pevsfreedom]

Using an adapter with a 2" barlow is fine for the barlowed laser method.

As "Big Jim Slade" mentioned, are you sure you are not running out of focus travel? That is, do you rack the drawtube all the way in or out and still can't reach focus?

At what you consider to be the focus point, do stars look like comets or do they look like donuts?

Jason

I guess I could use a little bit more of 'focus travel' though I've never heard of that term. It seems like I always need a little more, perhaps the tube will fix that. 

I suppose they look more like comets, fuzzy and hazy. 

[pevsfreedom]

That depends on the scope so the only way to know for sure is to try it out.

So first of all set up in daylight and point the scope at a distant landmark. CAUTION - Don't point anywhere near the sun!

Wind the focusser in as far as it will go.

Slowly wind it out till the distant object comes into focus.

If you still can't get it into focus with focusser all the way out then wind it all the way back in, attach the extension tube and start again.

If it still does not come to a focus it's going to get trickier so try the above first and report back.

I've had no problems focusing on tree's or something (kind of hard to find a landmark in Los Angeles). Star's on the other hand are difficult. 

[ronin]

This sounds like not enough inward travel for the focuser and eyepiece.

Q: Is there a 2" adaptor in the 10" as there are in the 8" scopes ?

Thinking that the 2" adaptor is still in when it needs to be removed, fairy common mistake on the 8"/200P's.

Check your focuser.

What happens is the scope can take a 2" or 1.25" eyepiece.

For shipping they put the 1.25" adaptor in the 2" adaptor, and it all looks like that is how it should work, so users initially leave it like that.

That is the problem, you should in reality have either the 2" adaptor in OR the 1.25" adaptor in - not both.

If both are in then the eyepiece is too far back for stars and planets but OK for trees and buildings.

Take the eyepiece out, tug at the 1.25" adaptor and remove that, then look at the (hopefully) 2" adaptor and gently take that out.

Assuming there is one there put it to one side and put the 1.25" adaptor back in, then an eyepiece, then go look at the moon ot something.

At first keep it simple, forget extension tubes, barlows and collimators.

[Dom1961]

The cap is a collimator cap, I made one out of the eyepiece dust cap. All you do is drill through the middle of the dust cap, I just hit a nail through it but be careful you don't crack the cap. You can buy one and it's £5 from FLO. Alternatively if you have a 3D printer you can just model one to the right size and 3D print it. I was going to 3D print mine but couldn't be bothered to model it.

[pevsfreedom]

This sounds like not enough inward travel for the focuser and eyepiece.

Q: Is there a 2" adaptor in the 10" as there are in the 8" scopes ?

Thinking that the 2" adaptor is still in when it needs to be removed, fairy common mistake on the 8"/200P's.

Check your focuser.

What happens is the scope can take a 2" or 1.25" eyepiece.

For shipping they put the 1.25" adaptor in the 2" adaptor, and it all looks like that is how it should work, so users initially leave it like that.

That is the problem, you should in reality have either the 2" adaptor in OR the 1.25" adaptor in - not both.

If both are in then the eyepiece is too far back for stars and planets but OK for trees and buildings.

Take the eyepiece out, tug at the 1.25" adaptor and remove that, then look at the (hopefully) 2" adaptor and gently take that out.

Assuming there is one there put it to one side and put the 1.25" adaptor back in, then an eyepiece, then go look at the moon ot something.

At first keep it simple, forget extension tubes, barlows and collimators.

It's a 2" focuser that accepts a 2->1.25" adapter. So I would say there is no 2" adapter as it's a 2" focuser, hopefully I understood you right. I'll try the KISS method too (keep it simple stoopid).

[pevsfreedom]

The cap is a collimator cap, I made one out of the eyepiece dust cap. All you do is drill through the middle of the dust cap, I just hit a nail through it but be careful you don't crack the cap. You can buy one and it's £5 from FLO. Alternatively if you have a 3D printer you can just model one to the right size and 3D print it. I was going to 3D print mine but couldn't be bothered to model it.

Good idea. You know it's funny my stepfather just bought a 3D printer yesterday, but I'll probably just use the drill (he has no idea how to use the printer yet), and oddly enough asked me if I needed anything for astronomy with it - what a coincidence. 

Do you use the collimator cap with the barlow'd laser method like in the article I mentioned? 

[Jason D]

Maybe I missed it but I do not recall reading anything about using a collimation cap in that article. The article was referring to using a color filter as a screen for the reflected center spot shadow.

Jason

[Dom1961]

Good idea. You know it's funny my stepfather just bought a 3D printer yesterday, but I'll probably just use the drill (he has no idea how to use the printer yet), and oddly enough asked me if I needed anything for astronomy with it - what a coincidence. 

Do you use the collimator cap with the barlow'd laser method like in the article I mentioned? 

No, I don't have a Barlow yet so I only use the laser, If you need anything modelling just let me know, or you can learn. I use tinker cad, it's free and easy to use.

[jbjh]

OP, as a a fellow Angeleno, might I recommend taking your scope out to Woodland Hills Camera and Telescope and having them collimate it for you the first time? Get your scope running right and enjoy it!

And for what it's worth, I happened to be in the store when a gentleman brought his new 8" Orion Dob in. He was having focusing problems, and when I tried his focuser, there was a sticking point in the travel that he thought was the mechanical stopping point. I cranked the tube out more past the burr or whatever was stopping the tube's travel. I had to leave after that, but the shop was going to disassemble the focuser, clean the gears and regrease everything.

Sent from 80ms in the future

Much peace

Jimmy

[pevsfreedom]

I brought it to Woodland shop today, was quoted $150-200 to fix the collimation, though they apparently have no clue what's wrong with it. Called the company, they told me there's nothing they can do. The secondary reflects the laser into the dot on the primary fine, and then it is literally impossible to get the laser to reflect back upon itself, so somehow the primary is totally out of whack, and the people in the shop seemed dumbfounded, and now I'm stuck with this $900 thing and can't use it unless I shell out more $, bummer. 

[carastro]

Are you sure your laser collimator is collimated itself?  It might be giving you false readings.

I owned a Newtonian for a few months and found this guide by Astrobaby (who is an SGL member) absolutely invaluable.

http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

Carole 

[Tinker1947]

If the secondary is aligned ok, hold a piece of paper over the scope so you can see the laser dot and move the primary mirror adjusters so it gets back to the secondary and then back to the collimating tool surface.....

[pevsfreedom]

Are you sure your laser collimator is collimated itself?  It might be giving you false readings.

I owned a Newtonian for a few months and found this guide by Astrobaby (who is an SGL member) absolutely invaluable.

http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

Carole 

I know for a fact my laser's OUT of collimation because the laser would spin if I spun the laser in the focuser. They used a 'better' one at the shop along with a cheshire and cap and couldn't collimate it (unless I gave them $200). I was told there is some bad mojo going on between the secondary and the primary, and the primary is apparently way out of whack. 

[pevsfreedom]

If the secondary is aligned ok, hold a piece of paper over the scope so you can see the laser dot and move the primary mirror adjusters so it gets back to the secondary and then back to the collimating tool surface.....

They tried that as well The manufacturer wants me to call back tomorrow and he'll walk me through removing the primary mirror to check for defects. 

[Stu]

I would say adjusting the primary is far easier than getting the secondary correct. Will be interesting to hear what the manufacturer says, I certainly would not pay $150 to have it collimated.

[pevsfreedom]

Yeah I laughed when he told me that, manufacturer did as well. Something's wrong and I'll find it, just not sure what yet. 

[pevsfreedom]

So after 4 hours yesterday and 10 minutes today I think I'm in some kind of ballpark here, IDK why the guys at the store couldn't get it or why I couldn't get it yesterday:

My question now is, is the 'diffraction pattern' or whatever you wanna call coming off the laser dot (on the primary) normal? I wanna say no, but at least I'm in a ballpark now. I also know it's off, I can get it dead center but that 'pattern' doesn't go away. 

[jetstream]

If you want to easily collimate your telescope buy a Cheshire collimation tool. It will only take you a half an hour the first time, 5 minutes after that. A laser, used like you are doing, doesn't place the sec under the drawtube and is susceptible to "play" in the focuser and miscollimation of the laser itself. In other words nothing is repeatable. A barlowed laser is fine for the primary but..... if it ain't workin' try something else...

To me $150.00 to collimate your scope is ridiculous. Take time to learn how to use a Cheshire, buy one and then enjoy your scope. Apologies if I am too blunt.