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Atl
professor emeritus
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Reged: 04/13/12

New Perspectives on Newtonian Collimation
      #5655323 - 01/31/13 11:36 PM

Just bought this book. Ever since I changed my spider and secondary on my 12.5" dob 2 weeks ago I have had an ongoing pain in the rear with collimating it. Every time I get it aligned one edge of the mirror disappears. I adjusted my mirrors and focuser like a demon...even wore out a screw holding the focuser on and had to buy a new one. I just read to chapter 4 in this book...2 times...then a third with my telescope making the adjustments as I came to them in the reading. Almost without effort everything fell into place...no cut off edge...all concentric. On this forum I have seen Vic and Jason patiently guide frustrated newbies...including me...sometimes to little or no avail. This book made it clear to me immediately with no question. Good job Vic. This was the best money I spent on my telescope. If your having trouble with collimation just read it. I feel almost stupid it was so simple to correct.

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okieav8rModerator
I'd rather be flying!
*****

Reged: 03/01/09

Loc: Oklahoma!
Re: New Perspectives on Newtonian Collimation new [Re: Atl]
      #5655352 - 01/31/13 11:49 PM

Good post Atl. New Perspectives is a great little book. Lots of great information on collimation, and just the right size to keep in an accessory case--which is where mine stays, so it's handy when I need it.

Vic and Jason have indeed been a great deal of help in demystifying a process that looks harder than it really is, and explaining how it all works. They do us all a great service.


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Jason D
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Reged: 10/21/06

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Re: New Perspectives on Newtonian Collimation new [Re: okieav8r]
      #5655529 - 02/01/13 03:18 AM



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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: New Perspectives on Newtonian Collimation new [Re: Atl]
      #5655664 - 02/01/13 07:03 AM

May I ask where you bought the book from? I struggled with my collimation and after reading Jason and Vic's posts here especially the pictures I was able to get a perfect collimation with my XT8. I would like to learn more so I can help others at my local club who have difficulty.

Thanks Ken


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rlmxracer
sage
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Reged: 11/09/11

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Re: New Perspectives on Newtonian Collimation new [Re: Jason D]
      #5655669 - 02/01/13 07:09 AM

Jason and Vic led me out of the collimation woods. I owe many thanks to them and others who chimed in. I just recieved my Catseye Infinity XLK autocollimator yesterday and look forward to finally getting it perfect. Only problem is I'm due for yet another week of clouds .

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hottr6
Carpal Tunnel
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Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: New Perspectives on Newtonian Collimation new [Re: kenrenard]
      #5655797 - 02/01/13 08:32 AM

Quote:

May I ask where you bought the book from?



http://bit.ly/14uVf2F


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Jerry-rigged
sage


Reged: 01/30/12

Loc: Coastal Texas.
Re: New Perspectives on Newtonian Collimation new [Re: hottr6]
      #5655849 - 02/01/13 09:00 AM

Quote:

Quote:

May I ask where you bought the book from?



http://bit.ly/14uVf2F






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turtle86
Pooh-Bah Everywhere Else
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Reged: 10/09/06

Re: New Perspectives on Newtonian Collimation new [Re: okieav8r]
      #5655903 - 02/01/13 09:32 AM

Quote:

Good post Atl. New Perspectives is a great little book. Lots of great information on collimation, and just the right size to keep in an accessory case--which is where mine stays, so it's handy when I need it.

Vic and Jason have indeed been a great deal of help in demystifying a process that looks harder than it really is, and explaining how it all works. They do us all a great service.




+1

Props too to Don Pensack, aka Starman1.


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: New Perspectives on Newtonian Collimation new [Re: hottr6]
      #5655908 - 02/01/13 09:33 AM

I understood that! My question was did the person by directly from Vic's site? I would like to give the original author the most royalty's from the sale as possible. Since his time and effort went into the book.

Thank you though for your response.

Ken


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CatseyeMan
Vendor (Cats Eye Collimation)
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Reged: 12/16/04

Loc: Madison, AL USA
Re: New Perspectives on Newtonian Collimation new [Re: kenrenard]
      #5655987 - 02/01/13 10:07 AM

With the publication of the 5th Edition in which I was able to contribute with my expertise with the PovRay scneario graphics illustrations to compliment his text, Vic graciously offered and authorized me to be the exclusive distributor for his wonderful booklet.

Order Vic's book Here


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rockethead26
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Reged: 10/21/09

Loc: Arizona, USA
Re: New Perspectives on Newtonian Collimation new [Re: CatseyeMan]
      #5655990 - 02/01/13 10:09 AM

It's a must have for newtonian owners.

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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: New Perspectives on Newtonian Collimation new [Re: CatseyeMan]
      #5655999 - 02/01/13 10:14 AM

Thank you Jim,
I just ordered the book today. I am looking forward to reading it.

Ken


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CatseyeMan
Vendor (Cats Eye Collimation)
*****

Reged: 12/16/04

Loc: Madison, AL USA
Re: New Perspectives on Newtonian Collimation new [Re: kenrenard]
      #5656017 - 02/01/13 10:18 AM

Quote:

Thank you Jim,
I just ordered the book today. I am looking forward to reading it.

Ken




Ships Today!


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: New Perspectives on Newtonian Collimation new [Re: CatseyeMan]
      #5656159 - 02/01/13 11:14 AM

Great News!


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Vic Menard
Post Laureate
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Reged: 07/21/04

Loc: Bradenton, FL
Re: New Perspectives on Newtonian Collimation new [Re: kenrenard]
      #5656436 - 02/01/13 02:06 PM

First, I'd like to thank everyone for their kind comments and support.

As I mentioned in an earlier post (in another collimation thread), the fifth edition of New Perspectives... is the result of forum contributions by members like you. These threads provided the foundations for the fifth edition. There's also the incredible graphic contributions by Jim Fly and Jason Khadder (and more than a few "kick-in-the-pants" motivational correspondences from Jim to get the finished booklet published!)

Hearing success stories from Cloudy Nights members like you makes my day!

(a lot!)


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Starman1
Vendor (EyepiecesEtc.com)
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Reged: 06/24/03

Loc: Los Angeles
Re: New Perspectives on Newtonian Collimation new [Re: Vic Menard]
      #5657430 - 02/02/13 12:06 AM

Vic has held my hand more than once leading me through the woods of misunderstanding. Sometimes it took a to get me to see the issue properly.

I recently went back and re-read New Perspectives again, and I can honestly say it was the first time I understood everything completely and even thought about a few things I think he'd left out.
[Vic, I'll send you an email one day soon when I get my head out from under SEO changes to my website.]

But OMG, what did we do back in the days before Vic and Jason and Jim Fly and Howie Glatter and Tectron, etc.? I even read their names on Australian, British, French and German Forum sites (and hosts of special interest groups). The collimation gurus we have among us are world-renowned!


I've noticed even the manufacturers of telescopes are paying attention and making their scopes more dimensionally stable to hold collimation better.


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Vic Menard
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Reged: 07/21/04

Loc: Bradenton, FL
Re: New Perspectives on Newtonian Collimation new [Re: Starman1]
      #5657909 - 02/02/13 11:00 AM

Quote:

...I recently went back and re-read New Perspectives again, and I can honestly say it was the first time I understood everything completely and even thought about a few things I think he'd left out.
[Vic, I'll send you an email one day soon when I get my head out from under SEO changes to my website.]



That's why I have an addendum website (plus, it's impossible to include animations in a book!) I've been thinking about providing additional information on alignment (and misalignment) signatures and their relative sensitivity to alignment errors, including both "passive" and laser signatures.

Quote:

...I've noticed even the manufacturers of telescopes are paying attention and making their scopes more dimensionally stable to hold collimation better.



As they say, "The cat is out of the bag." As manufacturers push focal ratios ever shorter, maintaining axial tolerances will require diligence to minimize mechanical stability issues and ensure optimal performance.


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precaud
scholastic sledgehammer
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Reged: 12/05/12

Loc: north central New Mexico
Re: New Perspectives on Newtonian Collimation new [Re: Vic Menard]
      #5658130 - 02/02/13 01:14 PM

Quote:

I've been thinking about providing additional information on alignment (and misalignment) signatures and their relative sensitivity to alignment errors, including both "passive" and laser signatures.




Boy that would be incredible if you could do that.


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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: New Perspectives on Newtonian Collimation new [Re: precaud]
      #5658179 - 02/02/13 01:40 PM

I have the Third Edition (didn't know there was now a Fifth) from 1991. A long time! When I collimate a Newtonian, I've often wondered why some enterprising garage machinist doesn't invent a better spider.

Edited to add:

After posting the preceding, it occurred to me that maybe I was ignorant of new hi-tech spiders. After all, my "newest" Newtonian dates from 1978. What I see online from Protostar and Astrosystems are essentially the spiders we had 60 years ago! You turn tiny collimation screws (the "modern" upgrade is hex-head screws), then run to the eyepiece end to see what the effect was. The final adjustment usually requires physically twisting the secondary holder. One of my scopes has a Novak spider whose hub is unthreaded. The shaft of the secondary holder is held by a nut at each end, but the essential fit is loose, and there's lots of play in the alignment. What a mess!

Edited by Calypte (02/02/13 01:54 PM)


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MDB
super member


Reged: 06/06/12

Loc: Idaho
Re: New Perspectives on Newtonian Collimation new [Re: Calypte]
      #5658546 - 02/02/13 05:20 PM

Thank you Vic & Jim! I just ordered the 5th. edition and look forward to reading and learning. Thank you especially for your willingness to share your hard earned knowledge so freely.

Mike


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MDB
super member


Reged: 06/06/12

Loc: Idaho
Re: New Perspectives on Newtonian Collimation new [Re: MDB]
      #5658556 - 02/02/13 05:25 PM

I forgot, thank you too Alt for the thread and bringing the new edition to our attention.

Mike


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Fred1
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Reged: 09/19/07

Loc: Somewhere in the Orion Spur
Re: New Perspectives on Newtonian Collimation new [Re: Calypte]
      #5658564 - 02/02/13 05:29 PM

Quote:

I have the Third Edition (didn't know there was now a Fifth) from 1991. A long time! When I collimate a Newtonian, I've often wondered why some enterprising garage machinist doesn't invent a better spider.

Edited to add:

After posting the preceding, it occurred to me that maybe I was ignorant of new hi-tech spiders. After all, my "newest" Newtonian dates from 1978. What I see online from Protostar and Astrosystems are essentially the spiders we had 60 years ago! You turn tiny collimation screws (the "modern" upgrade is hex-head screws), then run to the eyepiece end to see what the effect was. The final adjustment usually requires physically twisting the secondary holder. One of my scopes has a Novak spider whose hub is unthreaded. The shaft of the secondary holder is held by a nut at each end, but the essential fit is loose, and there's lots of play in the alignment. What a mess!




Well, if you go to the StarStructure Yahoo Group and look in the Photos section, look at pics of the Axial Slide Hub.


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Atl
professor emeritus
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Reged: 04/13/12

Re: New Perspefctives on Newtonian Collimation new [Re: Fred1]
      #5659836 - 02/03/13 11:53 AM

Now that I understand the basic process there is another activity I can engage in when it is daytime or cloudy...use my autocollimator to see how tight I can get it. That seems to be a fun thing in it's own right...at least for nerdy types like me.

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okieav8rModerator
I'd rather be flying!
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Reged: 03/01/09

Loc: Oklahoma!
Re: New Perspefctives on Newtonian Collimation new [Re: Atl]
      #5660146 - 02/03/13 02:55 PM

Quote:

Now that I understand the basic process there is another activity I can engage in when it is daytime or cloudy...use my autocollimator to see how tight I can get it. That seems to be a fun thing in it's own right...at least for nerdy types like me.




Once you get the hang of it, collimation really is an enjoyable chore to do.


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tag1260
scholastic sledgehammer
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Reged: 10/07/12

Loc: Ohio, USA
Re: New Perspefctives on Newtonian Collimation new [Re: okieav8r]
      #5660193 - 02/03/13 03:26 PM

I agree. Once it clicks it's a fairly easy task with the right tools. I only wish I could see those darn extra images more clearly through my autocollimator!!

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Starman1
Vendor (EyepiecesEtc.com)
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Reged: 06/24/03

Loc: Los Angeles
Re: New Perspefctives on Newtonian Collimation new [Re: tag1260]
      #5660303 - 02/03/13 04:28 PM

Quote:

I agree. Once it clicks it's a fairly easy task with the right tools. I only wish I could see those darn extra images more clearly through my autocollimator!!




I have a truss tube, and I found that if I remove the shroud (or pull it up to the UTA), and get sunlight on the center marker (oblique, but direct sunlight--scope pointed perhaps 45 degrees away from the sun and only about half of the mirror in direct sun), all 4 images are BRIGHT and very easily seen.
The reflected light will exit the scope through the poles, so watch where it goes--you don't want the reflected light to hit anyone. In the afternoon, point directly above the sun by, perhaps, 30 degrees so the reflected light goes back to the sky.
Paradoxically, that makes cheshire collimation more difficult--the edge of the dark circle is hard to see--so I point it farther away from the sun until the center marker is in shadow. Usually, this means simple movement up and down if you are on the same altitude line as the sun but pointed well above the sun--down for sun on the marker, up for shadow.
But if the sun hits the marker, even the 4th image (#3 of P-1-2-3) is fairly bright and easy to see.

In a tube scope, this might result in pointing too close to the sun, so I would try pointing below the sun in the morning or above the sun in the afternoon (so the passage of time will NOT take the sun into the image) where the sky is very bright.

If doing this at night, a bright LED light aimed at the center marker (Catseye has a nifty little light for this) will make all 4 images easily visible, though using the cheshire will be a little more difficult unless you flood the entire system with light.

Just a note about pointing the scope anywhere near the sun--you have to be very aware of where your scope is pointed and where the sun is. The sunlight would heat up the mirror a lot if you left the mirror (or a portion of it) in the sun for very long, but a few minutes to collimate doesn't heat the mirror much at all because the light is reflected. If you have kids around, I would try collimation with the scope pointed much farther away from the sun. You CAN see all four images in the AC with the scope pointed at bright daytime sky. I just mention the sun idea IF you have a truss tube and IF you're not nervous about doing this and IF you are having trouble seeing all 4 images in the AC's central peephole. The lateral images in the second peephole in the XLK autocollimator are more easily seen with less light.

Also, once you see all 4 of the images, you will see them with less light.


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Doc Bob
professor emeritus
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Reged: 02/27/09

Loc: Maryland, USA
Re: New Perspefctives on Newtonian Collimation new [Re: Starman1]
      #5660335 - 02/03/13 04:51 PM

Just ordered a copy also!
My friend sent me his 2006 year model Zhumell 10" Dob - if I like it he'll sell it to me. I have a CPC1100 and am familiar with collimation . . . with a CAT - the Newt is a different animal and I need all the help I can get. Lookin' forward to the UPS truck.

Bob


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CatseyeMan
Vendor (Cats Eye Collimation)
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Reged: 12/16/04

Loc: Madison, AL USA
Re: New Perspefctives on Newtonian Collimation new [Re: Starman1]
      #5660509 - 02/03/13 06:16 PM

Quote:

...If doing this at night, a bright LED light aimed at the center marker (Catseye has a nifty little light for this) will make all 4 images easily visible, though using the cheshire will be a little more difficult unless you flood the entire system with light....




The trick here when using the autocollimator is to attach the clip light to the extreme side of the OTA opposite the focuser & aimed at the spot; when using the Cheshire, move the clip light in on the spider toward the center of the OTA adjacent to the Secondary pointing toward the spot.


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Atl
professor emeritus
*****

Reged: 04/13/12

Re: New Perspefctives on Newtonian Collimation new [Re: CatseyeMan]
      #5660861 - 02/03/13 10:53 PM

I dedicated about 6 hours to the autocollimator section of the book today. I didn't achieve a single triangle...but got down to two ghost images directly under the original in about 3 passes. My Cheshire and sighttube agreed as well. The seeing tonight was fair. I took the scope out under a layer of cloud cover. Normally the e and f of triangulum are a challenge...not so as of tonight. Sirius b was also intermittently visible in a 9mm eyepiece. My star images are not perfect but they are as fine as I have ever seen with this 12.5" dob. My 90mm mak had fluffy star images in comparison.

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dan777
professor emeritus
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Reged: 11/16/07

Loc: Indiana
Re: New Perspefctives on Newtonian Collimation new [Re: Atl]
      #5660893 - 02/03/13 11:18 PM

Quote:

e and f of triangulum



e and f of the trapezium. Triangulum is the constellation


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dan777
professor emeritus
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Reged: 11/16/07

Loc: Indiana
Re: New Perspefctives on Newtonian Collimation new [Re: dan777]
      #5660898 - 02/03/13 11:23 PM

to you Vic.
I've been through two editions of your book.


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Atl
professor emeritus
*****

Reged: 04/13/12

Re: New Perspefctives on Newtonian Collimation new [Re: dan777]
      #5660915 - 02/03/13 11:37 PM

Lol...yeah I also observed M33 Triangulum galaxy so I guess that turned me around...Orion is not close to there...oh well you got the gist...

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FineArt
member


Reged: 01/26/12

Re: New Perspectives on Newtonian Collimation new [Re: MDB]
      #5661009 - 02/04/13 12:44 AM

Get the XLK autocollimator. It really makes life easy.

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Vic Menard
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Reged: 07/21/04

Loc: Bradenton, FL
Re: New Perspectives on Newtonian Collimation new [Re: dan777]
      #5661360 - 02/04/13 09:32 AM

Quote:

to you Vic.
I've been through two editions of your book.



Thanks for your support and your persistence!
I hope you've had (or will have) the opportunity to share your expertise with others.


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kenrenard
Carpal Tunnel


Reged: 12/13/12

Loc: Dunmore, PA
Re: New Perspectives on Newtonian Collimation new [Re: Vic Menard]
      #5664855 - 02/06/13 09:23 AM

Vic,
Just got your new edition of the book 2 days ago. I think I am going to need to read some sections a few times. Wow lots of information! I see so many new folks asking for eyepiece advice, when they have never attempted collimation. After spending a few nights working with my reflector I am getting great views of Jupiter. It is really amazing how much a under $500.00 telescope can show if properly collimated.

I am still a beginner but I am learning quite a bit just from reading this book. Great job.


Ken


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Atl
professor emeritus
*****

Reged: 04/13/12

Re: New Perspectives on Newtonian Collimation new [Re: kenrenard]
      #5668171 - 02/08/13 12:15 AM

My project this week was to upgrade my focuser from a very wobbly rack and pinion to the Orion basic crayford. My scope is sonotube and tube modification was required. It got messy but it turned out well in the end. after completely disassembling the scope and reassembling it the skills I learned in this book once again stood me in good stead. 10 minutes after completing the project I have perfect collimation.

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csrlice12
Postmaster
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Reged: 05/22/12

Loc: Denver, CO
Re: New Perspectives on Newtonian Collimation new [Re: Atl]
      #5668604 - 02/08/13 09:41 AM

Ordered it Yesterday, its on its way.....

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Daud
sage


Reged: 08/05/06

Loc: AZ, Scottsdale
Re: New Perspectives on Newtonian Collimation new [Re: csrlice12]
      #5668911 - 02/08/13 12:28 PM

Collimation is for me like going to the dentist. Despite having the history of one-to-one instruction by Vic on WSP, I have still ordered the book...

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hottr6
Carpal Tunnel
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Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: New Perspectives on Newtonian Collimation new [Re: Vic Menard]
      #5670501 - 02/09/13 10:53 AM

Quote:


As they say, "The cat is out of the bag." As manufacturers push focal ratios ever shorter, maintaining axial tolerances will require diligence to minimize mechanical stability issues and ensure optimal performance.



With the prices of micro-gearboxes being so low, I'll not be surprised if we will soon see OAG technology being used for auto-active-collimation, even during an observing session. Just like the big boys.


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Mike Harvey
Pooh-Bah


Reged: 03/01/04

Loc: Orlando, FL.
Re: New Perspectives on Newtonian Collimation new [Re: Daud]
      #5674439 - 02/11/13 04:55 PM

Quote:

Collimation is for me like going to the dentist. Despite having the history of one-to-one instruction by Vic on WSP, I have still ordered the book...




I've had "one-on-one" collimation instruction from Vic for years and STILL need refresher courses and updates!

But, for the most part, Vic taught me a long time ago how to (with apologies to Dr. Strangelove) "STOP WORRYING AND LOVE COLLIMATION"!

I think it's safe to say that, without Vic's guidance, I would NEVER have discovered the joys of truly 'fast' Newtonians. I certainly would not be the completely-satisfied owner of a large f/3.6 (!) scope!!!

But it IS more difficult to learn by reading about it than it is by seeing it done .
Maybe one day Vic will produce a VIDEO companion to "New Perspectives".
I think a DVD with selectable tracks for each step in collimation would be a "must-have" for anyone who owns, or is thinking of buying, a Newt!

Mike Harvey


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FirstSight
Duke of Deneb
*****

Reged: 12/26/05

Loc: Raleigh, NC
Re: New Perspectives on Newtonian Collimation new [Re: Mike Harvey]
      #5674722 - 02/11/13 08:04 PM

I agree completely that collimation is much easier to understand by show-me than by read-me.

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starman345
Wait, I'm Thinking
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Reged: 07/06/10

Loc: New Brunswick, Canada
Re: New Perspectives on Newtonian Collimation new [Re: Mike Harvey]
      #5675263 - 02/12/13 04:53 AM

Quote:

Maybe one day Vic will produce a VIDEO companion to "New Perspectives".




+1
Got my New Perspectives copy a few days ago, well spent money, thanks Vic


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backwoody
Pooh-Bah


Reged: 01/08/07

Loc: Idaho USA
Re: New Perspectives on Newtonian Collimation new [Re: Vic Menard]
      #5676915 - 02/13/13 01:09 AM

Yeah Vic, Jim, Jason, Don...you guys taught many of us. Nice to acknowledge your expertise once in a while...

c/s always, and good collimation,


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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: New Perspefctives on Newtonian Collimation new [Re: CatseyeMan]
      #5679301 - 02/14/13 12:00 PM

CatseyeMan,

Quote:

The trick here when using the autocollimator is to attach the clip light to the extreme side of the OTA opposite the focuser & aimed at the spot; when using the Cheshire, move the clip light in on the spider toward the center of the OTA adjacent to the Secondary pointing toward the spot.




Thanks for this tip. I've tried collimating in a dark room with a red light flashlight clipped to a spider vane but there was not enough light to see the donuts in my autocollimator. I probably didn't have it positioned as you advice. IMO, it's best to make trial runs at home of everything you can before you actually give it a try at the dark site.

I use an AstroSystems 1.25" autocollimator. I'll try your tip to see if it makes a difference for the AstroSystems model.

Mike


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precaud
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679326 - 02/14/13 12:12 PM

Mike, I just got the AstroSystems 1.25" autocollimator and what worked for me last night was a diffuse bright light shining toward the tube at an angle from out of the FOV. The object seems to be to flood the tube with indirect light. This was with the standard round paper donuts in my scopes, which I plan on changing out in the next week or so with more reflective ones, which should help.

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Sarkikos
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679370 - 02/14/13 12:32 PM

FWIW, personally I learn much better by reading and trying things out for myself than by having somebody show me how to do it. Just how I roll.

I just now ordered a copy of the book. I think I've been able to learn how to collimate very closely by reading threads here on CN - my avatar attests to that! - but it's nice to have all that knowledge condensed into one easy-to-access source. I'll undoubtedly pick up some more tips and refinements from the book.

Mike


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Re: New Perspefctives on Newtonian Collimation new [Re: precaud]
      #5679376 - 02/14/13 12:38 PM

Quote:

Mike, I just got the AstroSystems 1.25" autocollimator and what worked for me last night was a diffuse bright light shining toward the tube at an angle from out of the FOV. The object seems to be to flood the tube with indirect light. This was with the standard round paper donuts in my scopes, which I plan on changing out in the next week or so with more reflective ones, which should help.




Now, when I'm at my dark site at night I need to make sure that light is red and does not disturb other observers. So that will limit somewhat the brightness of the light and the location. I'd at least want to make sure that the light is inside the OTA, not sitting somewhere outside the telescope. I have a solid tube Dob, so if I attach the red light to a spider vane, that should be OK.

Using the autocollimator is easy during the day. IME, as long as the sun has not set for very long, the sky is still bright enough to stack the donuts.

Yes, I don't have a reflective triangle to mark the primary center, just a paper circle.

Mike


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precaud
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679475 - 02/14/13 01:27 PM

Yeah, the LED clipped inside the tube sounds like the way to go in those circumstances.

The AS AC came with a square reflective spot, just over 1/2" across. Seems like an odd choice of shape, not so easy to identify the inverted reflections as with a triangle.


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Re: New Perspefctives on Newtonian Collimation new [Re: precaud]
      #5679565 - 02/14/13 02:02 PM

Check the accuracy of the perpendicularity of the AC mirror by rotating the AC in the focuser and checking if the images unstack. If the images don't change, your mirror is fine.
It's wise to do this with any passive collimation tool just to be certain everything is nice and well-machined.


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Atl
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679574 - 02/14/13 02:06 PM

Quote:

Quote:

Mike, I just got the AstroSystems 1.25" autocollimator and what worked for me last night was a diffuse bright light shining toward the tube at an angle from out of the FOV. The object seems to be to flood the tube with indirect light. This was with the standard round paper donuts in my scopes, which I plan on changing out in the next week or so with more reflective ones, which should help.




Now, when I'm at my dark site at night I need to make sure that light is red and does not disturb other observers. So that will limit somewhat the brightness of the light and the location. I'd at least want to make sure that the light is inside the OTA, not sitting somewhere outside the telescope. I have a solid tube Dob, so if I attach the red light to a spider vane, that should be OK.

Using the autocollimator is easy during the day. IME, even if the sun has not set for very long, the sky is still bright enough to stack the donuts.

Yes, I don't have a reflective triangle to mark the primary center, just a paper circle.

Mike




Here is what I settled on. In daylight get the collimation right and use a laser once set up at night to touch up the collimation. It seems to work fine.


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Re: New Perspefctives on Newtonian Collimation new [Re: Atl]
      #5679595 - 02/14/13 02:17 PM

Quote:

Here is what I settled on. In daylight get the collimation right and use a laser once set up at night to touch up the collimation. It seems to work fine.




I think an autocollimator will produce a much closer collimation than a laser. I'd place the laser collimators at about the same level of accuracy as a Cheshire/sight-tube, and even then, only if the laser itself has been collimated.

What I do is collimate with my Cheshire/sight-tube and autocollimator at home either looking toward a light in the house or, even better, at the sky outside a window. Then I make sure to arrive at the dark site before sunset so I'll have enough light to check the collimation with my autocollimator. Usually the collimation is fine. Sometimes it just needs a slight tweak on the Bob's Knobs at the secondary to restack the donuts.

So far this has worked out OK, since I'd much rather set up my equipment in the daylight than in the dark with a red-light flashlight on my forehead. Of course, being able to collimate accurately in the dark would come in handy if I arrive late at the dark site.

Mike


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Sarkikos
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Re: New Perspefctives on Newtonian Collimation new [Re: Starman1]
      #5679607 - 02/14/13 02:22 PM

Don,

Quote:

Check the accuracy of the perpendicularity of the AC mirror by rotating the AC in the focuser and checking if the images unstack. If the images don't change, your mirror is fine.
It's wise to do this with any passive collimation tool just to be certain everything is nice and well-machined.




I've checked out my AstroSystems 1.25" AC in this way and it was right on.

Mike


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Jason D
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679652 - 02/14/13 02:43 PM

Quote:

I think an autocollimator will produce a much closer collimation than a laser. I'd place the laser collimators at about the same level of accuracy as a Cheshire/sight-tube, and even then, only if the laser itself has been collimated.




The quality of tools has a huge impact on the above statement. Autocollimators have much higher quality bar to get that extra accuarcy. Without that extra attention to quality, the autocollimator will not provide an additional accuracy -- might even making it worse.

Check the info in the following link
http://www.firstlightoptics.com/blog/how-to-choose-a-telescope-autocollimator...

Jason


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Jason D
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679661 - 02/14/13 02:45 PM

Quote:

I've checked out my AstroSystems 1.25" AC in this way and it was right on.




Make sure to do the test the proper way. Do not stack all reflections then rotate. Unstack a little to see all 4 reflections then rotate.

Jason


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Sarkikos
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Re: New Perspefctives on Newtonian Collimation new [Re: Jason D]
      #5679697 - 02/14/13 03:01 PM

Jason,

Quote:

Quote:

I think an autocollimator will produce a much closer collimation than a laser. I'd place the laser collimators at about the same level of accuracy as a Cheshire/sight-tube, and even then, only if the laser itself has been collimated.




The quality of tools has a huge impact on the above statement. Autocollimators have much higher quality bar to get that extra accuarcy. Without that extra attention to quality, the autocollimator will not provide an additional accuracy -- might even making it worse.




Well, if we were to compare a good quality autocollimator with a good quality laser collimator, which do you think would give a closer collimation?

I've gotten very good results with the AstroSystems autocollimator. I've never seen a laser collimator that was as accurate. But then again, I've never paid multiple hundreds for a laser collimator. On the other hand, IIRC the autocollimator only cost about $50.

Mike


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Jeff Morgan
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Re: New Perspectives on Newtonian Collimation new [Re: starman345]
      #5679722 - 02/14/13 03:15 PM

Quote:

Quote:

Maybe one day Vic will produce a VIDEO companion to "New Perspectives".




+1
Got my New Perspectives copy a few days ago, well spent money, thanks Vic




I've always been frustrated by getting good axial alignment and still having some skew in my diagonal holder. After Perspectives I finally saw how easy the solution was. And using the image of the shroud screw heads in the autocollimator was a definite "aha" moment - I never would have thought of it on my own.

I hope Vic gets an asteroid or something named after him for his contribution!


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Starman1
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Re: New Perspectives on Newtonian Collimation new [Re: Jeff Morgan]
      #5679791 - 02/14/13 03:57 PM

Alas, if using the "new Method" of collimation (Unidirectional Secondary Offset), the optical axis is tilted slightly toward the focuser and the angle of reflection at the secondary is greater than 90 degrees.
That's fine, because superb collimation can be achieved.
But, there are consequences:
1) The image of the secondary mirror will not be exactly round. It will appear ever-so-slightly shortened in the up tube/down tube direction. If you make the secondary mirror's reflective surface coincident with the inside edge of a sght tube, you will see this. It's tiny, but it's there.
2) The screws on the outside of the secondary shroud will not appear equally visible. That shroud will be slightly tipped relative to the optical centerline, making screws on the long edge of the shroud more visible than the screws on the short edge of the shroud. Admittedly, the effect is fairly small, but it's real, and it's visible. It's because the sides of the shroud are not in the same line as the optical axis.

To eliminate #1 and #2 above, classical offset (bi-directional secondary offset) needs to be employed. Then the sides of the secondary shroud will be parallel to the optical axis and the secondary will appear exactly round in outline in the sight tube.

And the larger the amount of offset, the greater the degree of #1 and #2 above as seen through collimation tools.

Again, it is not a great amount, and near-perfect collimation can be achieved. But the "New Model" (UDO) of collimation does have this issue.


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Atl
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Re: New Perspectives on Newtonian Collimation new [Re: Jeff Morgan]
      #5679793 - 02/14/13 04:00 PM

I had the same issue. Putting paper behind the secondary showed me how messed up my secondary was... simple idea, but not obvious to me. I still have trouble with the autocollimator figuring out what knobs to turn to move those little triangles different ways, but it is happening.

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Jason D
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679813 - 02/14/13 04:15 PM

Quote:

Well, if we were to compare a good quality autocollimator with a good quality laser collimator, which do you think would give a closer collimation?



If you have a quality autocollimator and you apply it correctly starting with CDP using the single pupil autocollimator then yes it will be more accurate. Both quality and technique are required to get that extra accuracy with an autocollimator. Without the two, your collimation will be as good -- if not worse -- than a quality laser collimator.

Quote:

I've gotten very good results with the AstroSystems autocollimator. I've never seen a laser collimator that was as accurate. But then again, I've never paid multiple hundreds for a laser collimator. On the other hand, IIRC the autocollimator only cost about $50.



But if a lower quality $50 autocollimator does not give you any extra accuracy then it is a lesser value than a quality $100 one.
Refer to the autocollimator evaluation link I provided. If your $50 autocollimator pass the evaluation then you have a good collimator for a lower price.
I am not suggesting that you go off and spend a $100 on a quality autocollimator. That is your decision. Everyone is free to spend their money whichever way they want.

Jason


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precaud
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Re: New Perspefctives on Newtonian Collimation new [Re: Jason D]
      #5679864 - 02/14/13 04:42 PM

That I'm aware of, the AS autocollimator is the only game in town for 1.25" . Please correct me if I'm wrong.

They are $45, or $35 when bought with the Lightpipe combo tool.

When checked at quadrant points, mine does not pass the rotation test, whether left loose or tightened on the focuser. The reflections' pattern moves cyclically with the tool's rotation. Leaving one with the question: which, if any, of these positions are correct?


Edited by precaud (02/14/13 05:22 PM)


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Jason D
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Re: New Perspefctives on Newtonian Collimation new [Re: precaud]
      #5679919 - 02/14/13 05:23 PM

Quote:

That I'm aware of, the AS autocollimator is the only game in town for 1.25" . Please correct me if I'm wrong.




There is also 1.25" JSP Easy Tester autocollimator which is the lowest quality autocollimator in the market.


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Sarkikos
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Re: New Perspefctives on Newtonian Collimation new [Re: precaud]
      #5679927 - 02/14/13 05:30 PM

I suppose, then, as with many astronomy products, you have the luck of the draw whether or not you will receive an excellent, good or mediocre sample. Just as we should star test telescopes to determine their quality, we should also test our collimation tools. On the other hand, throwing more money at a problem is no guaranteed method of solving it.

Mike


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Jason D
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679972 - 02/14/13 06:04 PM

Quote:

we should also test our collimation tools.



Absolutely.

Quote:

On the other hand, throwing more money at a problem is no guaranteed method of solving it.



That is why everyone needs to do their own research and decide how to best spend their money.


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precaud
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5679978 - 02/14/13 06:07 PM

Quote:

There is also 1.25" JSP Easy Tester autocollimator which is the lowest quality autocollimator in the market.



Yes, but, as you well know, it's not really worth mentioning.

Quote:

I suppose, then, as with many astronomy products, you have the luck of the draw whether or not you will receive an excellent, good or mediocre sample.



Absolutely... test and verify everything we must, as best we can. But the difference here is, this is a collimation tool, with pretty clear performance expectations based on its description. The way the AstroSystems autocollimator is designed, the alignment accuracy is accomplished by the adjustment of the three screws on the top. Theoretically, every one of them could come out properly adjusted...


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Atl
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5680189 - 02/14/13 08:43 PM

Quote:

I think an autocollimator will produce a much closer collimation than a laser. I'd place the laser collimators at about the same level of accuracy as a Cheshire/sight-tube, and even then, only if the laser itself has been collimated.




I meant using a sight tube/cheshire/ autocollimator, and just using a laser to touch it up in the dark.


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precaud
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Re: New Perspefctives on Newtonian Collimation new [Re: Atl]
      #5680281 - 02/14/13 09:54 PM

The manufacturer's response:
"The mirrors in our autocollimators are aligned optically on a 100 foot path, giving 2-3 arc minute accuracy. I don't believe that the accuracy of the ID of a drawtube is accurate enough to see any deviation."

So what exactly is being said here? That, no matter what the tool's rotated orientation, if the reflections stack up, that's good enough and any better than that is not visible? And it doesn't matter if another rotation unstacks the reflections?

Is there any data that supports or refutes his statememt?


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Re: New Perspefctives on Newtonian Collimation new [Re: Atl]
      #5680322 - 02/14/13 10:19 PM

Quote:

Quote:

I think an autocollimator will produce a much closer collimation than a laser. I'd place the laser collimators at about the same level of accuracy as a Cheshire/sight-tube, and even then, only if the laser itself has been collimated.




I meant using a sight tube/cheshire/ autocollimator, and just using a laser to touch it up in the dark.




Yes, I know, but I would be concerned that the laser could mess up the collimation worse than a slight misalignment that the telescope might suffer in transit to the site. I'd rather take my chances with the slight misalignment.

Mike


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Atl
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5680330 - 02/14/13 10:25 PM

Recently I have compared my laser and Cheshire and they are the same accuracy wise. I admit my skill with the autocollimator is just beginning to show.

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Re: New Perspefctives on Newtonian Collimation new [Re: Atl]
      #5680566 - 02/15/13 01:53 AM

Accuracy:
1.Sight Tube = collimated laser
2.Cheshire = Barlowed laser = Krupa Collimator
3.Autocollimator = class by itself and will collimate to a higher degree of accuracy than #1 or #2. Where this tool's accuracy is paramount is a. if you use a coma corrector in the system, or b. you are trying to design or re-engineer a telescope to be capable of holding collimation as it moves up and down.


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Re: New Perspefctives on Newtonian Collimation new [Re: Starman1]
      #5680953 - 02/15/13 09:23 AM



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precaud
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Re: New Perspefctives on Newtonian Collimation new [Re: Sarkikos]
      #5681380 - 02/15/13 12:42 PM

I want to continue to explore this matter, but I'll do it in a new thread.

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Re: New Perspectives on Newtonian Collimation new [Re: precaud]
      #5681461 - 02/15/13 01:13 PM

Quote:

The manufacturer's response:
"The mirrors in our autocollimators are aligned optically on a 100 foot path, giving 2-3 arc minute accuracy. I don't believe that the accuracy of the ID of a drawtube is accurate enough to see any deviation."



I don't find it too difficult to correct the focuser axial alignment to an accuracy of +/-0.02-inch using a Glatter laser with my 88-inch focal length Dobsonian. This reflects an accuracy a bit less than one arc minute.

This same error will cause the P-3 alignment (after CDP) in the central pupil to unstack 0.04-inch, which is quite obvious. A 3 arc minute error would cause almost 4X the error.

Quote:

So what exactly is being said here? That, no matter what the tool's rotated orientation, if the reflections stack up, that's good enough and any better than that is not visible? And it doesn't matter if another rotation unstacks the reflections?



I think what's being said is that as long as the unstacked error (through a full 360-degree rotation) is less than the axial alignment tolerance, the tool is useful. If there's no observable unstacking error, then the tool's internal alignment and registration is essentially transparent--any error you see is attributable to the focuser and/or primary mirror axes.

Quote:

Is there any data that supports or refutes his statement?



There's good documentation on the axial alignment tolerances. These tolerances vary according to aperture, focal ratio and application.


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Re: New Perspectives on Newtonian Collimation new [Re: Starman1]
      #5681528 - 02/15/13 01:38 PM

Quote:

Accuracy:
1.Sight Tube = collimated laser



I'll assume we're discussing axial alignment (not secondary mirror placement). Then, the sight tube cross hairs aligned to the primary mirror center spot is equivalent to the collimated thin beam laser aligned to the primary mirror center spot. But if you include readability, I would argue that with a thin beam laser I can achieve a focuser axial alignment correction of +/-0.02-inch, about twice the accuracy I can achieve using the sight tube cross hairs. But perhaps that's just me.

Quote:

2.Cheshire = Barlowed laser = Krupa Collimator



Pretty much true as long as the Cheshire pupil is kept small, otherwise, parallax can complicate the read. The Barlowed laser and Krupa collimator are both parallax free. Nils Olof's balanced Barlowed laser is more insensitive to residual focuser axial tilt error than the other tools.

Quote:

3.Autocollimator = class by itself and will collimate to a higher degree of accuracy than #1 or #2.



The single pupil autocollimators can show residual focuser axial errors magnified 2X (P-3 with a CDP), that's better than #1. But stacking by itself does not necessarily indicate a better primary mirror axial alignment than #2 (P-1 stacks when the axes intersect at the COC, and 2-3 disappear when P-1 are stacked). A two pupil autocollimator improves the read accuracy by providing a very precise assessment of parallelism, but for simple, direct interpretation, I still prefer #2.

Quote:

Where this tool's accuracy is paramount is a. if you use a coma corrector in the system...



Which puts real demands on the axial alignments...

Quote:

...or b. you are trying to design or re-engineer a telescope to be capable of holding collimation as it moves up and down.



Depending on the axial tolerances, a good laser might work as well, but if the tolerances are particularly stringent, a good autocollimator is likely to be your best bet.


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graffias79
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Re: New Perspectives on Newtonian Collimation new [Re: hottr6]
      #5683476 - 02/16/13 12:56 PM

Quote:

Quote:

May I ask where you bought the book from?



http://bit.ly/14uVf2F





Congratulations, that's probably the most sarcastic thing I've ever seen on the internet. And that's saying something!


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Sarkikos
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Re: New Perspectives on Newtonian Collimation new [Re: graffias79]
      #5683513 - 02/16/13 01:15 PM

That is funny!

Mike


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Re: New Perspectives on Newtonian Collimation new [Re: Sarkikos]
      #5683624 - 02/16/13 02:22 PM



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