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Laser Collimators - Which one should I get? HELP!

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#1 TahoeNoob

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Posted 31 March 2013 - 04:36 PM

Here's the deal. I want to buy a laser collimator, so that I can barlow laser collimate my two reflector scopes. The thing is, I'm not sure which one to get or what I actually need.

As I said, I have two reflector telescopes:

1) Orion XT10i F4.7
2) Edmund Scientific 4", classic, reflector with a quite high F number.

I've also got a 2x barlow, and an Orion Cheshire site tube... if that matters to you.

The Orion scope will take either a 2" or 1.25" eyepiece. The Edmond scope will only take a 1.25" eyepiece, so I'm thinking that I need a 1.25" collimator. CatsEye seems out of the question, because they only sell 2" laser collimators. (If I'm reading their site correctly.) Howie Glatter sells 1.25" laser collimators, but I'm totally confused as to what I'd need to buy! (Would I need both a Blug and a TubLug? (Or does the TubLug come with the laser insert module/thing?) And then there is the Parallizer! Would I need one of those too? Really? I couldn't save that for later?)

Ugh! :bawling: I'm trying not to break the bank here! It's enough to make me think that maybe a simple Deluxe Orion 1.25" collimator might be enough! (I've read that they, the collimators, don't always arrive collimiated so well. Can they be adjusted?)

Any, and all, advice is more than welcome! I'm really confused, and don't have a clue. :crazy: Thank you!

#2 obin robinson

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Posted 31 March 2013 - 05:01 PM

I have this one:

http://www.hotechusa...tegory-s/22.htm

I got it from a CN member and I ABSOLUTELY LOVE IT!!!!

obin :)

#3 TahoeNoob

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Posted 31 March 2013 - 05:10 PM

Thank you...

That makes me feel better. The thing I don't understand is why some people swear that you have to get a Howie Glatter or Catseye collimator. Those suckers cost a lot of money, if you can even figure out what you need. To hear somebody say they ABSOLUTELY LOVE something that's cheaper, makes me very happy! LOL

Too many expensive hobbies. I think that's what the problem is. :)

#4 Jeff2011

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Posted 31 March 2013 - 05:14 PM

I have the Orion deluxe laser collimator and have found it to do a good job if I combine it with a centering eyepiece holder and a Barlow.

#5 panhard

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Posted 31 March 2013 - 05:15 PM

These hava a great reputation. glatter laser.

#6 Jon Isaacs

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Posted 31 March 2013 - 07:29 PM

Thank you...

That makes me feel better. The thing I don't understand is why some people swear that you have to get a Howie Glatter or Catseye collimator. Those suckers cost a lot of money, if you can even figure out what you need. To hear somebody say they ABSOLUTELY LOVE something that's cheaper, makes me very happy! LOL

Too many expensive hobbies. I think that's what the problem is. :)


You don't "have" to have Howie Glatter or Catseye tools but in my view, they are worth having and in the long run, they are less expensive because they last a lifetime. I bought my first laser collimator about 13 years ago, they were just hitting the market. The first one was very crude and I sent it back and bought a collimator from Howie Glatter. It's still going strong, aligned and precise. This is my thinking/experiences:

- One issue with most collimators is that the collimators themselves are not collimated, they need to be collimated when they arrive and do not stay in collimation. The test for this is to place the collimator in the focuser and rotate it while watching the spot on the mirror. If the spot is fixed, the collimator is fine. If the collimator is in need of collimation, it will make a circle.. The spec on a Howie Glatter collimator is 15 arc-seconds, that's 1mm at 45 feet.

- Another issue is durability. Howie's collimators are designed to take a beating, he aligns them, whacks them with a polyurethane block at least a dozen times and retests them. If the collimation has shifted, the collimator is not yet ready for prime time. Many collimators are not robust and shift collimation.

- Precise machining. A collimator that is a sloppy fit in the focuser makes collimation more difficult and is a potential source of error. Howie does the machining himself, his collimators are precisely machined so they fit smoothly but are not sloppy in the drawtube.

- Beam stop size. Howie's collimators produce a tight, circular beam, many less well made collimator produce a large, irregular pattern that can make aligning the secondary mirror difficult.

In the short run, a Howie Glatter collimator represents a real investment, it's real money. In the long run, it's a tool that will last a lifetime and remain accurate and durable.

There are a number of ways to collimate a Newtonian, a laser collimator is only one. If you are going to use a laser, don't cut corners.. And if you are going to use a laser to collimate a Newtonian, make sure you use Nils Olof Carlin's "Barlowed Laser" technique to adjust the primary mirror.

Jon

#7 TahoeNoob

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Posted 31 March 2013 - 08:00 PM

Jon,

Ok, but what actually has to be bought from Howie Glatter? He seems to sell his lasers separately from his tubes. (I'd want one of those tubes with the diagonal screen that allows you to view the screen from the back of the scope. I think he's calling it the TubLug.)

A TubLug, by itself, isn't enough... is it?

#8 panhard

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Posted 31 March 2013 - 08:50 PM

You need both. If you go that route.
The other quality option is this. catseye
Like Jon says buy once use it forever. I have owned others, but i will stick with my Catseye kit.
Both Jim & Howie are great guys to deal with.

#9 Pharquart

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Posted 02 April 2013 - 07:31 PM

I experienced exactly what you're going through: collimator analysis overload. So many options, and like eyepieces, wildly conflicting opinions on what minimum is required or recommended. I also started with the Cheshire combo tool.

To answer your question on Glatter products: you will need a laser at a minimum. The Blug and tuBlug are redundant--you'd only need one. The Blug is designed for truss-type tubes where you can see the inner end of the focuser draw tube. For your scopes with solid walls, you'd want the tuBlug that puts the target outside the scope so you can see it from the back end when you adjust the primary screws. The parallizer is an optional device that helps make sure the laser is centered in and parallel to the focuser. Some focusers are "sloppier" than others, and the laser won't be centered. Compression rings do a better job than single screws, but can still introduce an angle. The Hotech collimators (what I ended up getting because it fit by budget) have an o-ring type system on the business end to try to do the same thing. I found that my Hotech mounted in my 2"-1.25" adapter the right way was nicely centered so the dot didn't trace a circle when I spun the adapter in the focuser.

The perfect alignment part is very important when you align the secondary mirror, because an offset or angle introduced in the focuser will put your secondary off. Back before I got a laser, I found my Cheshire was off. Spinning it in the focuser caused the cross at the end to trace a circle. So I just adapted by adjusting the secondary until the circle was centered on my primary. Once the put in a Barlow to adjust the primary, the angle/offset drops out of the equation. As long as the broad circle of laser light coming out of the primary hits the center spot on your primary, the laser alignment isn't critical.

The tuBlug is just a combination Barlow and target system, albeit a well-made one. It will accept any laser of the correct size (1.25" or 2"). So you can get a less expensive laser (at the risk of having it be miscollimated itself or not as durable) and use it with a tuBlug.

I'm a frugal do-it-yourself type of guy, so I made my own version of a Blug. I found that the inside end of my focuser barrel was just over 2". So used a 2-1/8" hole saw (the kind used to drill a hole in a door for a doorknob) and cut through a 2x4. The diameter of the round scrap piece was 2" and fit perfectly in the focuser tube. I then used a 2-1/2" hole saw to cut through some thin plywood to make a 2-1/4" (or so) diameter circle. The hole saws automatically create a 1/4" pilot hole through the centers, so I lined up the holes and glued the 2 round pieces together. Then I made a paper "target" with concentric circles and glued it on the face of the plywood. Bingo: a target that fits in the inner end of my focuser drawtube. Not nearly as elegant as the Blug, and I have to walk around and look in the front end of the telescope to see the target rather than seeing it while adjusting the primary screws, but WAY less expensive. I added arrows on my paper target to help make the job easier. An arrow tells me which way to put the target in the tube (arrow points to the primary), and then the notes tell me which way to turn which screw on the primary to align everything. I can look at the target once and usually make the necessary screw turns the first time.

You might not be able to make a common target if your 2 scopes have different focuser sizes, but you could make 1 for each scope.

So, after a long-winded post, here's my recommendation. If you can afford it, get a Glatter laser and tuBlug. Problem solved. If, however, your budget is like mine, get a less expensive laser (they tend to come up used for $35-60) and use your own Barlow, and try to make your own target of some sort. (I also tried making something out of cardboard that would slip around the focuser tube rather than inside it.) You may have to fuss a little bit getting your secondary aligned perfectly if your laser is miscollimated, but once the secondary is set (and your Cheshire might do well enough here), the accuracy of the laser is less important for adjusting the primary.

Brian

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#10 Pharquart

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Posted 02 April 2013 - 07:31 PM

Backside view of my homemade target:

Brian

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#11 TahoeNoob

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Posted 02 April 2013 - 08:14 PM

Thank you for your reply! That actually helped me a LOT!

At this point, I'm leaning towards getting a TuBlug, and a 650nm laser collimator from Astronomics. I sent Astronomics an email and they told me that the TuBlug comes with a barlow built into it. (That was news to me, but good news. It means I wouldn't have to "stack" the barlow I already have below the TuBlug.)

https://www.astronom...lug_p18895.aspx

https://www.astronom...aser-collima...

#12 Jon Isaacs

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Posted 02 April 2013 - 11:17 PM

Thank you for your reply! That actually helped me a LOT!

At this point, I'm leaning towards getting a TuBlug, and a 650nm laser collimator from Astronomics. I sent Astronomics an email and they told me that the TuBlug comes with a barlow built into it. (That was news to me, but good news. It means I wouldn't have to "stack" the barlow I already have below the TuBlug.)

https://www.astronom...lug_p18895.aspx

https://www.astronom...aser-collima...


You can also just use a Barlow, a paper target for the Barlow and a laser collimator. That's what we did before the Blug and the Tublug, it works just fine, it takes a bit more care...

Jon

#13 Starman1

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Posted 02 April 2013 - 11:57 PM

Glatter makes an inexpensive barlow attachment for the bottom of his laser.
If you buy one, you should buy the 1.25"/2" version. It will fit in all focusers.
That and the barlow attachment is all you need. You don't have to be able to see the screen from below and pay the big bucks--you can stand up to look, bend over to turn a knob and stand up to look a few times as you align the primary--it's just not that difficult.
The Blug also works from above in a full-tubed scope, and it is a little easier to see than the barlow attachment on the bottom of the laser, but you would need both sizes of blug and that gets expensive.
So a simple solution is the dual-size laser and the simple thread-on barlow attachment.

But since money is a critical factor for you, why not get a 1.25" Astrosystems Light Pipe (a combination sight tube + cheshire) for $45, which will allow you to collimate both mirrors in both scopes with one tool? You will be able to save up your pennies for a Glatter system for later.
And, you will have a tool that is used to center the secondary under the focuser, one of the steps in collimation.

#14 TahoeNoob

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Posted 03 April 2013 - 12:42 AM

So, does the bottom of the laser, with the barlow attachment, extend down into the OTA (far enough) so that you can see where the laser light (or shadow of the primary's center mark) is being cast?

#15 Jon Isaacs

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Posted 03 April 2013 - 07:43 AM

So, does the bottom of the laser, with the barlow attachment, extend down into the OTA (far enough) so that you can see where the laser light (or shadow of the primary's center mark) is being cast?


It depends on the scope but I use the Self-Barlow attachment with my 10 inch F/5 GSO dob... It doesn't extend down into the OTA but I can see the face of the laser looking down from the front of the tube. I have a Blug but I almost always use the self-barlow, tube scope or truss.

Jon

#16 TahoeNoob

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Posted 03 April 2013 - 09:20 AM

I suppose I could get the 1.25"/2" laser with a Self-Barlow attachment, and if it turns out that I can't see the face of the laser... I could make a target the way Pharquart (Brian) did.

I suspect I'd be able to see the face on the 2" focuser, but I have my doubts on the 1.25" one.

The advantage of going this route would be that I wouldn't have to get a compression adapter, but I'm probably going to have to get one of those anyway, for my 1.25" eyepieces.

I'll continue thinking about it, but I have a much better understanding of what each item does now. I'll probably make a decision on what to buy, in about a week.

#17 Starman1

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Posted 03 April 2013 - 10:11 AM

I suppose I could get the 1.25"/2" laser with a Self-Barlow attachment, and if it turns out that I can't see the face of the laser... I could make a target the way Pharquart (Brian) did.

I suspect I'd be able to see the face on the 2" focuser, but I have my doubts on the 1.25" one.

The advantage of going this route would be that I wouldn't have to get a compression adapter, but I'm probably going to have to get one of those anyway, for my 1.25" eyepieces.

I'll continue thinking about it, but I have a much better understanding of what each item does now. I'll probably make a decision on what to buy, in about a week.

A small clip-on dental mirror attached to the spider would allow you to see up inside the focuser if you can't see the bottom of the laser with the self-barlow attachment. Or a small hand mirror. It won't be hard to see in a 2" focuser, but I agree it might be a little tough in a 1.25" focuser, so the small mirror would be practical.
And if you can avoid using an adapter when collimating a scope with a 2" focuser, you eliminate one possible source of laser misregistration in the focuser.

#18 andromada2013

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Posted 04 April 2013 - 02:11 PM

My first post - I tried the -Orion LaserMate Deluxe II Telescope Laser Collimator yesterday for the first time, my 12" XT12i mirror was 1-1/2" off center from the secondary, still have to test the results on a dark sky.
I recommend a laser for everyone with a Dobsonian. They go for about 50$

#19 Jon Isaacs

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Posted 04 April 2013 - 02:20 PM

My first post - I tried the -Orion LaserMate Deluxe II Telescope Laser Collimator yesterday for the first time, my 12" XT12i mirror was 1-1/2" off center from the secondary, still have to test the results on a dark sky.
I recommend a laser for everyone with a Dobsonian. They go for about 50$


Did you first test the collimation of the laser?

:question:

Jon

#20 Jon Isaacs

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Posted 04 April 2013 - 02:21 PM

A small clip-on dental mirror attached to the spider would allow you to see up inside the focuser if you can't see the bottom of the laser with the self-barlow attachment.



Finally, a thread with some teeth in it. :)

Jon

#21 Starman1

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Posted 04 April 2013 - 02:33 PM

Hi, and welcome to Cloudy Nights.
As you hang around here and read the thousands of posts, you'll pick up that lasers can be very valuable for a quick alignment of your mirrors if certain things hold true:
1) The laser is, itself, collimated, i.e. that the beam is completely parallel to the mechanical structure inserted in the focuser or adapter. This is usually not the case with inexpensive lasers, but they can be easily checked by rotating them around in the focuser, securing the laser at each stop point. If the beam rotates on the primary mirror in a circle, the laser is not collimated and cannot be used for collimation until it is collimated.
2) The laser fits the focuser accurately enough to have a repeatable registration. If removing the laser, reinserting it and securing the setscrew changes the tilt of the laser beam each time, attaining collimation will be difficult. Sometime, all that's necessary is to change the adapter in the focuser (as to a Glatter Parallizer or Antares collet-style adapter).
3) the secondary mirror is centered under the focuser. This is usually done with a sight tube (which can also be used to collimate the secondary to the focuser axis) or a laser with a holographic attachment.
The simple laser by itself does not guarantee the secondary is centered and correctly rotated, however.
4) You use a barlow with the laser to collimate the primary mirror. The return beam of the laser is not accurate enough to collimate the primary unless you follow it up with a cheshire, Krupa, or autocollimator, but if used with a barlow, it is as accurate as you need to be to align the primary.

The Orion LaserMate Deluxe is made by Farpoint and is usually collimated. You should check, but it probably is on. Here are some useful links:
Barlowed laser Primary collimation:
http://www.cameracon...collimation.pdf
Collimating your laser:
http://www.astromart...p?article_id=96
http://www.stark-lab.../llcc/llcc.html
http://www.cloudynig...php?item_id=520

#22 TahoeNoob

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Posted 04 April 2013 - 02:42 PM

At this point I'm (strongly) leaning towards Starman1's suggestion of a 1.25"/2" collimator with a barlow attachment.

The TuBlug would be nice, but I think it's a luxury that I can live without, and I like the idea of being able to insert the 2" collimator directly into my 2" focuser, without any adapter.

Starman1, I noticed that you don't have them in stock. Do you have any idea when they'll be available?

#23 andromada2013

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Posted 05 April 2013 - 03:18 PM

how do you test the collimation of the laser?

I was going to see if my moon photos would come out nice and sharp as my test.

this is what I had before the laser.

http://www.flickr.co.../in/photostream

#24 TahoeNoob

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Posted 05 April 2013 - 04:00 PM

There are two ways that I know of:

1) Put the collimator into your telescope's focuser and rotate it around. If the laser light swings an arc, the collimator isn't collimated correctly.

2) The other method is harder to describe without a picture. (Unfortunately, I didn't save a picture when I saw it explained.) Take a short 2x4 and pound 4 longish and stiff nails into it. You're creating two "X" shapes with the nails. Now place your collimator, horizontally, across the top of the two "X"s. (The tops of the "X"s are in effect "V"s.) Then, aim the collimator at a wall, however far away, and rotate the collimator in the "V"s. (Do not allow the 2x4 to move while you rotate the collimator.) If the light on the wall swings an arc/circle, you need to collimate your collimator.

Don't ask me how to collimate your collimator, because I've never owned one and don't know. Hopefully somebody else can answer that question, because I'd like to know too.

Good luck! :)

#25 Seldom

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Posted 05 April 2013 - 04:47 PM

I suspect if you try to collimate your laser you'll do more harm than good. If it doesn't pass have the manufacturer fix it. FWIW, I tried a check on my laser collimator by setting it on the edges of a solid but slightly open vice. I observed the laser rotated in a circle about 1/4" diameter on a wall 30' from the laser. Nils Olof Carlin said that degree of error was acceptable.






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