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Equipment Discussions >> Reflectors

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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
Carpal Tunnel
*****

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
*****

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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okieav8rAdministrator
I'd rather be flying!
*****

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)
*****

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
*****

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)
*****

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
scholastic sledgehammer
*****

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
scholastic sledgehammer
*****

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
Post Laureate
*****

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
*****

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
*****

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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