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Advice on a good laser collimator

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#1 NeutronStar79

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Posted 12 September 2019 - 02:08 AM

Hello,
I have just purchased a 12 inch F/5 truss tube Dobsonian, and it's a great step up from my 8 inch F/6. However, it is a bit less forgiving when it comes to collimation. My current Meade collimator is not very precise at all.

Honestly, it takes me ages to collimate with stars, and if Polaris is not available it's even worse. I find the laser to really inprove my observing experience, so I'm willing to spend money on a proper one which doesn't lose collimation and is very precise. I have a good MoonLite focuser which I think should help.

What are the best collimators out there? I have read a few positives about the Glatter ones. Anyone has experience with them?

Thanks!

#2 Jon Isaacs

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Posted 12 September 2019 - 06:57 AM

I have two Howie Glatter collimators.  A 1.25 inch I purchased almost 20 years ago and a 2 inch 635nm that I bought 12 years ago. Both are still going strong. 

 

For collimating Newtonians, I think there is no doubt that Howie Glatter collimators are the best.  They're precisely machined, aligned to a high standard, (1mm at 45 feet), internally, they're specially designed so they're very rugged.  I also have the Tublug and some other accessories.

 

These days, I think they're still the best but they're quite expensive.

 

Jon


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#3 NeutronStar79

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Posted 12 September 2019 - 10:12 AM

Thanks Jon for your advice!

#4 Mike Wiles

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Posted 12 September 2019 - 10:39 AM

There is the Howie Glatter laser, and then there is everything else. 

Buy the Glatter. 

Be happy. 

Live a prosperous life. 

Do yourself a favor and also buy the Tublug at the same time. 

Perfect collimation in about 2 minutes effort.  


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#5 Starman1

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Posted 12 September 2019 - 11:50 AM

Hello,
I have just purchased a 12 inch F/5 truss tube Dobsonian, and it's a great step up from my 8 inch F/6. However, it is a bit less forgiving when it comes to collimation. My current Meade collimator is not very precise at all.

Honestly, it takes me ages to collimate with stars, and if Polaris is not available it's even worse. I find the laser to really inprove my observing experience, so I'm willing to spend money on a proper one which doesn't lose collimation and is very precise. I have a good MoonLite focuser which I think should help.

What are the best collimators out there? I have read a few positives about the Glatter ones. Anyone has experience with them?

Thanks!

Excellent tools:

Passive (require no batteries, just sky light): Catseye, Astrosystems, Farpoint (Cheshire only)

Active (require batteries): Howie Glatter, Farpoint, Astrosystems (includes barlow attachment)

 

You can do a good job of collimation with any of the above.

If you want superb collimation, then add an autocollimator (best one is Catseye XLKP 2-pupil, second is Farpoint)


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#6 SandyHouTex

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Posted 12 September 2019 - 12:17 PM

I own a Glatter laser and a Svbony (sp.).  The Howie is way better except that I need a mirror to see where the laser hits the white target if it's in a focuser that's really deep.



#7 Jim7728

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Posted 12 September 2019 - 12:42 PM

These days, I think they're still the best but they're quite expensive.

 

 

I was quite astounded at the big price increase from the new proprietor  of the Howie Glatter laser and Tublug from what I payed just four years ago .

 

You get what you pay for, but I can see those on a budget shying away.


Edited by Jim7728, 12 September 2019 - 12:46 PM.

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#8 Starman1

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Posted 12 September 2019 - 12:45 PM

A decent alternative is the Farpoint laser + Cheshire, or the Astrosystems laser.

The laser dot is smaller on the Farpoint, but the Astrosystems barlow attachment is usable at night and the laser is very long, putting the screen

at the bottom of the focuser.


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#9 lakland5

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Posted 12 September 2019 - 03:12 PM

A decent alternative is the Farpoint laser + Cheshire, or the Astrosystems laser.

+1 on Don's recommendations. 

 

I use a Farpoint laser for collimating the secondary and an Astrosystems combination tool ("lightpipe,"  which is a sight tube w/crosshairs + Cheshire) for the primary, and find it quite easy and precise for f/4.7.

 

I've decided that I personally get a better read with the lightpipe than with barlowing the laser and feel it's _quite_ a bit more precise than the laser-with-diagonal-face-target I used for a while.  

 

Everybody eventually finds a method and combination of tools that, with practice, works well for them and this is mine--

 

RicA



#10 Jon Isaacs

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Posted 12 September 2019 - 03:51 PM

A decent alternative is the Farpoint laser + Cheshire, or the Astrosystems laser.

The laser dot is smaller on the Farpoint, but the Astrosystems barlow attachment is usable at night and the laser is very long, putting the screen

at the bottom of the focuser.

 

In hear stories that the Farpoint doesn't always arrive collimated. Don't know about the Astrosystems..

 

What do you hear?

 

Jon



#11 lakland5

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Posted 12 September 2019 - 04:30 PM

My Farpoint laser came in well-collimated (it was sold as a 2nd due to a small cosmetic blemish of some kind, I think) and has remained so over months of handling and bumpy dirt roads and everything so that's one data point.



#12 Starman1

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Posted 12 September 2019 - 04:32 PM

In my experience, no laser collimator is guaranteed to arrive collimated, though the Glatter comes close to 100%.

The Farpoint is a bit behind 100% and the Astrosystems is a tad behind that.

There is a profound price difference, though.

As a consumer, I would always check my laser collimator for perfect alignment, whatever the brand.

 

It's also a matter of tolerances.  If the beam is off 1/4" at 80' (my sample of the Farpoint), how far is it off in my 5' focal length?  0.016".

That's smaller than the beam where it hits the primary, and the tolerances for that alignment, even with a Paracorr 2, is about double that.

So, within tolerances.

Farpoint will collimate the laser for free if it is returned to them, as will Starlight Instruments.

Astrosystems starts out well-collimated at their warehouse.  The question is, how does it arrive?  Usually pretty good.

And on that one, the Barlow attachment is included.

Doveryai, no proveryai. Trust, but verify.



#13 jtsenghas

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Posted 12 September 2019 - 05:28 PM

I know that this is the Reflector forum, and not the ATM, Optics and DIY forum, but I want to mention that one can take full advantage of the precise barlowed laser method for excellent primary axial alignment without much investment.

 

The aim of the focuser at the primary is not nearly as critical as the aim of the primary back to the focuser, particularly for fast focal ratios. The generally accepted tolerance for the aim of the primary, or primary axial alignment, in millimeters is 0.005 times the cube of the focal ratio. This drops quickly below a half millimeter at sub f/5 ratios. 

 

Nils Olof Carlin, who we lost to an untimely death in 2017, wrote an excellent article on using this method with a cheap Barlow lens more than 15 years ago in Sky and Telescope Magazine. His article can be found here.

 

I've dabbled with various homemade tools that are customized for specific scopes that use this technique, including making the target conical for improved visibility at various angles. My thread on that topic can be found here.

 

I've realized that most people don't necessarily have the tools at my disposal for variations on this theme, but I'm about to cobble up a couple simpler versions that just require assembly of the right pieces and a homemade target that can be adapted from a cheap filter. I've ordered a few very inexpensive components that haven't come in yet to do so.

 

Note that Nils suggested in his article that the target could even be made from a red filter. This would transmit virtually all the light from a cheap red laser collimator. 

 

Remember, if you diverge light from the focal plane of your scope with a Barlow, the return shadow of the primary collimation target is full sized and won't even budge noticeably even when the laser is wiggled. The error it shows for placement will be twice your actual collimation error. 

 

The Glatter tools are excellent. I'd rather spend that much money on a good eyepiece than a collimation tool, though. 


Edited by jtsenghas, 12 September 2019 - 06:04 PM.

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#14 Jon Isaacs

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Posted 12 September 2019 - 06:07 PM

In my experience, no laser collimator is guaranteed to arrive collimated, though the Glatter comes close to 100%.

The Farpoint is a bit behind 100% and the Astrosystems is a tad behind that.

There is a profound price difference, though.

As a consumer, I would always check my laser collimator for perfect alignment, whatever the brand.

 

It's also a matter of tolerances.  If the beam is off 1/4" at 80' (my sample of the Farpoint), how far is it off in my 5' focal length?  0.016".

That's smaller than the beam where it hits the primary, and the tolerances for that alignment, even with a Paracorr 2, is about double that.

So, within tolerances.

Farpoint will collimate the laser for free if it is returned to them, as will Starlight Instruments.

Astrosystems starts out well-collimated at their warehouse.  The question is, how does it arrive?  Usually pretty good.

And on that one, the Barlow attachment is included.

Doveryai, no proveryai. Trust, but verify.

 

Howie aligned each collimator so it was within 15 arc-seconds. That's 1 mm at 45 feet. He then whacked it at least a dozen times on a polyurethane block and retested it. It had to meet spec.

 

For me, it's the robustness that's important. I don't want to find out that my collimator is misaligned when I need the darn thing.. sending it back is not an option at that point. I do carry my original 1.25 Howie as back up, it's close to 20 years old and I do have passive tools but still..

 

I believe the Howie Glatters were the best and they were affordable. Today, the prices have risen to a point where I would have difficulty justifying the cost. I don't really remember what I paid but today, the 635nm 2 inch plus the TuBlug, the Holographic attachment, the self Barlow and the variable brightness switch would be $665 plus tax and shipping.  

 

I'd probably go with the Farpoint and the TuBlug or just go with a 2 inch Barlow and do it the way I did before the TuBlug hit the seen. 

 

Jon


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#15 Starman1

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Posted 12 September 2019 - 06:26 PM

The Glatter lasers are not quite that accurate today, on average, at least from my tests.

I have a first surface mirror 40' from my v-block, which reflects back at a graph paper plot next to the laser at 80' away from the beam source.

I've collimated a laser that was so far out the beam missed the graph paper entirely.

Most of the newer lasers have no more than a 1/2" runout at worst and it usually only takes the turn of one screw to bring that to 1/4"

That's not quite the accuracy of Howie's 1.78mm at 80', but it's good enough for most commercial scopes up to about 25".

Every now and then I get one that turns on its own beam at that distance, but that's unusual.



#16 jtsenghas

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Posted 12 September 2019 - 06:50 PM

Again, I don't think it is worth getting so hung up on the axial alignment of the laser itself, which is why cheap ones suffice. You can spin the collimator in the focuser while gently registering it against the shoulder of the draw tube. As long as the circle it describes in the center spot of the primary is approximately centered, you've nailed it adequately for aiming the focuser.

 

If you use Vic Menard's collimation tolerances linked at the bottom of Jim Fly's Catseye Collimation Tools web page, you'll see that for the OP's 12" scope the focuser only needs to be aimed at the primary within 1.5 mm if a Paracorr is used, or 9.2 mm if one isn't; not that I advocate being that sloppy.

 

Even if the laser collimator is not well aligned it is easy to see if it describes centered circles when spun.

 

When a Barlow is added to tune the aim of the primary, the important step here, it matters not a bit if the collimator beam is a touch off either. The diverging beam still originates from the focal plane and doesn't budge noticeably even when you wiggle the laser.

 

When I'm really feeling OCD, I follow up with a tweak using a homemade dual pupil autocollimator. Some nights I even convince myself that I can actually see the improvement.

 

Don't forget! We're not in this hobby to spend our evenings looking at red dots or shadows of circles! Have you had a really good look at the Lagoon Nebula lately? 


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#17 jtsenghas

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Posted 12 September 2019 - 07:00 PM

Mind you, I have no criticism of anyone who finds the investment of the Glatter Tools purchased now through Starlight Instruments worth it to them personally. This helps to support a good company that makes many quality items for this hobby. We were told when Starlight Instruments would continue to market these tools after we lost Howie in 2017, that a portion of the proceeds would go to his widow. That's another good reason to purchase them.

 

I just can't justify paying Nagler Eyepiece prices for something I've satisfied myself I can do well with simple homemade tools. 



#18 jtsenghas

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Posted 12 September 2019 - 08:35 PM

Honestly, it takes me ages to collimate with stars, and if Polaris is not available it's even worse.

I meant to mention earlier, one way to improve star collimation is to use a technique I first saw described by Gary Seronik. It works especially well on Polaris if your scope isn't a tracking one. 

 

Look at a defocused star, either inside or outside of focus, using an eyepiece in millimeters that matches the f/ratio of your scope. This gives you 25 times your inches of aperture.

 

If the defocused star shows an off centered secondary shadow, bring your collimation in this way: First move the defocused star around in your field of view until you find where the image is in fact concentric between the secondary shadow and the disk. Then, with the image left there, DON'T MOVE THE SCOPE and tweak your collimation knobs to drive that image to the center of your field of view.

 

If desired, repeat with an even higher power eyepiece. THIS WORKS! 



#19 Jon Isaacs

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Posted 12 September 2019 - 09:38 PM

Again, I don't think it is worth getting so hung up on the axial alignment of the laser itself, which is why cheap ones suffice. You can spin the collimator in the focuser while gently registering it against the shoulder of the draw tube. As long as the circle it describes in the center spot of the primary is approximately centered, you've nailed it adequately for aiming the focuser.

 

If you use Vic Menard's collimation tolerances linked at the bottom of Jim Fly's Catseye Collimation Tools web page, you'll see that for the OP's 12" scope the focuser only needs to be aimed at the primary within 1.5 mm if a Paracorr is used, or 9.2 mm if one isn't; not that I advocate being that sloppy.

 

Even if the laser collimator is not well aligned it is easy to see if it describes centered circles when spun.

 

When a Barlow is added to tune the aim of the primary, the important step here, it matters not a bit if the collimator beam is a touch off either. The diverging beam still originates from the focal plane and doesn't budge noticeably even when you wiggle the laser.

 

When I'm really feeling OCD, I follow up with a tweak using a homemade dual pupil autocollimator. Some nights I even convince myself that I can actually see the improvement.

 

Don't forget! We're not in this hobby to spend our evenings looking at red dots or shadows of circles! Have you had a really good look at the Lagoon Nebula lately? 

 

I don't think it is quite that easy... When the laser itself is a poor fit in the focuser, which is typical of inexpensive lasers, rotating it and looking for the center may not describe a precise circle.  I have seen such collimators be inches out of alignment. I saw one that didn't even hit a 13.1 inch Coulter mirror..  Such lasers may not even work with the Barlowed laser technique.

 

And too, the Paracorr 2 has considerably better correction than the Paracorr 1 so the tolerance is appropriately tighter.  

 

But this is how I see it:

 

I don't want to spend my evenings looking at red dots or shadows of circles or messing trying to get a laser to work. 

 

That is why I want a collimator that is robust, accurate, and reliable.  I want a collimator that I can trust.  With collimator that doesn't fit the focuser properly, that may shift collimation, that is not accurately aligned, I may end up messing around getting the darn thing to work.   As I said previously, I've had my one HG collimator for nearly 20 years, the HG other for 12 years.  I have used them literally thousands of times.  They've never let me down.  Collimation is easy and straightforward, it takes me longer to get them out of the tool box and out the cases than it does to collimate the scope.

 

Sure you can make the inexpensive lasers work, wrap them in tape, collimate them in V-Blocks and hope they don't shift on the way out to dark skies.  Hope they don't just die.  

 

When I bought my first Howie Glatter, there was only one other choice, the Kendrick.  The Asian collimators hadn't hit the market.  Rod Mollise recommended I buy the Howie Glatter.  I am sure glad I did.  An original Howie Glatter might be overkill, maybe it doesn't need to fit the focuser so precisely, maybe it doesn't need to be aligned to 15 arc-seconds, maybe it doesn't need to be tested by beating on it.. But it sure is nice.. 

 

Jon


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#20 jtsenghas

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Posted 13 September 2019 - 05:41 AM

Okay, I haven't seen Lasers so uselessly out that they don't describe at least reasonably tight circles when rotated, nor have I seen any extremely loose either so that tape would be needed. If the shoulder is engaged gently during rotation to eliminate tilt, the body shouldn't shift more than its diametical clearance, which is trivial.

 

I am just trying to impress upon the OP that if he has a basic laser collimator already, he needs only a Barlow and a bit of effort to achieve excellent collimation on his new 12" f/5.

 

As I said, I have nothing against those who choose to buy the best and appreciate it. I just know I can do extremely well with cheap Lasers and homemade stuff, as evidenced by the well stacked images I get when I install a dual pupil autocollimator (yes, homemade) and rotate it also. 


Edited by jtsenghas, 13 September 2019 - 05:42 AM.


#21 Jon Isaacs

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Posted 13 September 2019 - 05:53 AM

Okay, I haven't seen Lasers so uselessly out that they don't describe at least reasonably tight circles when rotated, nor have I seen any extremely loose either so that tape would be needed. If the shoulder is engaged gently during rotation to eliminate tilt, the body shouldn't shift more than its diametical clearance, which is trivial.

 

I am just trying to impress upon the OP that if he has a basic laser collimator already, he needs only a Barlow and a bit of effort to achieve excellent collimation on his new 12" f/5.

 

As I said, I have nothing against those who choose to buy the best and appreciate it. I just know I can do extremely well with cheap Lasers and homemade stuff, as evidenced by the well stacked images I get when I install a dual pupil autocollimator (yes, homemade) and rotate it also. 

 

I have seen such lasers.  And in laser discussions on this very forum, such lasers are discussed.  Many of the inexpensive lasers do not have much of a shoulder for registration.. And then there is the issue of alignment of the adapter in a 2 inch focuser.  

 

My own thinking is that if you are not going to buy a quality laser, it's better to stick with passive tools. They won't suddenly die on you and leave you holding the bag. 

 

Jon


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#22 Vic Menard

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Posted 13 September 2019 - 10:02 AM

...My own thinking is that if you are not going to buy a quality laser, it's better to stick with passive tools.

Or have the expertise to sort out why your economy laser is giving inconsistent alignment reads  waytogo.gif


Edited by Vic Menard, 13 September 2019 - 01:09 PM.

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