Go Back   IceInSpace > Equipment > Equipment Discussions

Reply
 
Thread Tools Rate Thread
  #1  
Old 25-09-2010, 02:48 PM
richardda1st (Richard)
Registered User

richardda1st is offline
 
Join Date: May 2009
Location: Melton, Victoria, Australia
Posts: 372
AstroSystems Autocollimator - 1.25" or 2"

As I'm waiting for a delivery (3-4 weeks) from Astrosystems I would like to add to my parcel an Autocollimator, but can't choose which one.

My choice is between the 1.25" Autocollimator at $45 or the 2" for $89. What are the practical benefits if any for choosing the 2".
I have noticed the "Catseye" people don't do a 1.25" but do recommend the Astrosystems 1.25" for those who want one.

I have read that the autocollimator is far more accurate than any laser as it uses multiple reflections. Now as most focusers have some sort of slop when fitting any tool to it, will this same slop have the same detrimental effect on the autocollimator as it does on the laser.
As the autocollimator is far more accurate will this slop have less negative effect on the final setting.

Thanks
Richard

Last edited by richardda1st; 25-09-2010 at 08:44 PM.
Reply With Quote
  #2  
Old 25-09-2010, 06:26 PM
qld
Registered User

qld is offline
 
Join Date: Aug 2007
Location: sydney australia
Posts: 168
Quote:
Originally Posted by richardda1st View Post
As I'm waiting for a delivery (3-4 weeks) from Astrosystems I would like to add to my parcel an Autocollimator, but can't choose which one.

My choice is between the 1.25" Autocollimator at $45 or the 2" for $89. What are the practical benefits if any for choosing the 2".
I have noticed the "Catseye" people don't do a 1.25" but do recommend the Astrosystems 1.25" for those who want one.

I have read that the autocollimator is far more accurate than any laser as it uses multiple reflections. Now as most focusers have some sort of slop when fitting any tool to it, will this same slop have the same detrimental effect on the autocollimator as it does on the laser.
As the autocollimator is far more accurate will this slop have less negative effect on the final setting.

Thanks
Richard
go for the 2inch its got a bigger image and i suggest that you change the colour of the round centre marker on your primary from a white one to a orange coloured one as it will be easier to see the multiple reflections and make them merge into one "donut" .the amount of adjustment to achieve this one donut is very little and bobs knobs are a big aid.
Reply With Quote
  #3  
Old 26-09-2010, 04:38 PM
richardda1st (Richard)
Registered User

richardda1st is offline
 
Join Date: May 2009
Location: Melton, Victoria, Australia
Posts: 372
Quote:
Originally Posted by qld View Post
go for the 2inch its got a bigger image and i suggest that you change the colour of the round centre marker on your primary from a white one to a orange coloured one as it will be easier to see the multiple reflections and make them merge into one "donut" .the amount of adjustment to achieve this one donut is very little and bobs knobs are a big aid.
I assume you use the 2" yourself. If you don't mind me asking, what brand is yours. Any comment on the quality of the Astrosystems autocollimator.

Thanks
Richard
Reply With Quote
  #4  
Old 26-09-2010, 05:39 PM
qld
Registered User

qld is offline
 
Join Date: Aug 2007
Location: sydney australia
Posts: 168
Quote:
Originally Posted by richardda1st View Post
I assume you use the 2" yourself. If you don't mind me asking, what brand is yours. Any comment on the quality of the Astrosystems autocollimator.

Thanks
Richard
hi Richard, i actaully own two astrosystem 2 inch barlowed laser collimators ,one orion laser collimator 1.1/4 inch and the usual collection of sight tubes and cheschires,,,,,,the auto collimator is the astrosystem 2 inch model.i have used the 1.1/4 inch astrosystem model as well but i found the two inch diameter gave better reflection due to its size.which ever collimator i use the final stage of collimation is using the auto collimator ,you will be surprised how much fine tuning is still involved....the unit is very well made the mirror is first surface ...hope that helps you
Reply With Quote
  #5  
Old 26-09-2010, 05:54 PM
richardda1st (Richard)
Registered User

richardda1st is offline
 
Join Date: May 2009
Location: Melton, Victoria, Australia
Posts: 372
Yes, it all helps.
I have been using an orion delux laser, which was okay sort of, until I tried to improve on it's own collimation, fixed it sort of, but it needs adjusting all the time, it's battery runs out by the time I get it close.

It will be nice to have a tool that doesn't need a battery.

Thanks again
Richard
Reply With Quote
  #6  
Old 26-09-2010, 08:02 PM
qld
Registered User

qld is offline
 
Join Date: Aug 2007
Location: sydney australia
Posts: 168
Quote:
Originally Posted by richardda1st View Post
Yes, it all helps.
I have been using an orion delux laser, which was okay sort of, until I tried to improve on it's own collimation, fixed it sort of, but it needs adjusting all the time, it's battery runs out by the time I get it close.

It will be nice to have a tool that doesn't need a battery.

Thanks again
Richard
you will find that its best used in the day time or at twilight
Reply With Quote
  #7  
Old 27-09-2010, 06:32 AM
Jason D's Avatar
Jason D (Jason)
Registered User

Jason D is offline
 
Join Date: Aug 2009
Location: California USA
Posts: 117
Richard,
The main advantage of the 2" over the 1.25" is providing a larger view to detect where all the reflections are. When your scope is somewhat miscollimated, reflections will unstack and many of these reflections will get out-of-view with the 1.25" autocollimator which makes it harder to stack them.
A 2" autocollimator does NOT make reflections brighter.
I do recommend using a 2" autocollimator over 1.25" given the focuser supports it.
As far as which 2" autocollimator to purchase, there are few things to keep in mind:
1- Reflectivity of the mirror. You need to be able to see the 4th reflection of the center spot. If you can’t then the autocollimator will not provide the desired accuracy.
2- Flatness of the mirror. If reflections change shape compared to the original center spot then the autocollimator is somewhat useless.
3- Mechanical accuracy if the autocollimator. To test it, rotate the autocollimator in the focuser without tightening any of the focuser’s set screws. Evaluate how well reflections maintain their positions. Little jittering is OK but if reflections shift their positions noticeably then the autocollimator is somewhat useless.

Based on my experience, only the Catseye autocollimator passes on all above items. My Astrosystem autocollimator passed item # 2 but it did not do as well on items # 1 & 3.
In the USA, the difference in price between a 2” Catseye autocollimator and a 2” Astrosystem is only $11 (referring to only the single pupil autocollimator) which is a little extra to pay to get a much better tool. But, I do not know what the difference would be in Australia.

One more thing. The autocollimator theory explanation in the Astrosystems website and documentation is incorrect and their procedure is incomplete and somewhat incorrect. The proper procedure to use an autocollimator is explained in the Catseye website.
Jason

Last edited by Jason D; 27-09-2010 at 07:44 AM.
Reply With Quote
  #8  
Old 28-09-2010, 06:17 PM
richardda1st (Richard)
Registered User

richardda1st is offline
 
Join Date: May 2009
Location: Melton, Victoria, Australia
Posts: 372
Thanks for you comments Jason. Your avatar tweeeeked some of my meurons and sent me back to the net.
From the catseye web page it appears that there is no shipping charge, so the price difference is as you say, must check, (no additional shipping from atsrosystem for me).

I do assume that the Astrosystems units will also be of good quality (but I do make an ass of myself on a regular basis). I appreciate your comments regarding the Astrosystems AC and will keep them in mind.

Richard

ps I'm confused as to weather you can use the AC in the dark, I have assssumed that all you need to do is shine a light down the tube.

Last edited by richardda1st; 28-09-2010 at 06:30 PM.
Reply With Quote
  #9  
Old 28-09-2010, 11:43 PM
Jason D's Avatar
Jason D (Jason)
Registered User

Jason D is offline
 
Join Date: Aug 2009
Location: California USA
Posts: 117
Quote:
Originally Posted by richardda1st View Post
ps I'm confused as to weather you can use the AC in the dark, I have assssumed that all you need to do is shine a light down the tube.
I do it all the time. I use one of these small clip-on LEDs which I clip either to the OTA rim or to one of the spider vanes. It works great.

Jason
Reply With Quote
  #10  
Old 29-09-2010, 10:15 AM
JethroB76's Avatar
JethroB76 (Jeff)
Registered User

JethroB76 is offline
 
Join Date: Oct 2005
Location: Tassie
Posts: 1,104
So an autocollimator will still possibly show significant miscollimation after the use of a decent barlowed laser collimator? So it would be worthwhile to get one as a finishing touch?
Reply With Quote
  #11  
Old 29-09-2010, 11:48 AM
Jason D's Avatar
Jason D (Jason)
Registered User

Jason D is offline
 
Join Date: Aug 2009
Location: California USA
Posts: 117
Quote:
Originally Posted by JethroB76 View Post
So an autocollimator will still possibly show significant miscollimation after the use of a decent barlowed laser collimator? So it would be worthwhile to get one as a finishing touch?


It all comes down to tool quality and knowledge.
For example, a quality barlowed laser tool used correctly will yield better results than an average autocollimator used incorrectly.

For example, Astrosystem autocollimator instructions are incomplete and will not get you the best results even if a perfect autocollimator is used. Their instructions ask the user to adjust the secondary mirror until all reflections converge and the background darkens. But that is insufficient. Just check the attached photos. As you can see, reflections seem to have converged and the background is darkened but collimation is way off for two while the third is OK. Astrosystems instructions are akin to asking someone to keep adjusting the secondary mirror until the laser beam retraces its path but that is not enough since the laser beam can retrace its path even when it strikes the primary mirror few inches off center.

Interestingly, Nils Olof Carlin and Vic Menard published enough information explaining the theory and the proper instructions to use single-pupil autocollimators several years ago yet Astrosystems did not make any effort to update and correct their instructions.

Jason

Proper instructions are in http://www.catseyecollimation.com/IN...e%20-%20R2.pdf
Attached Thumbnails
Click for full-size image (darkening.JPG)
10.6 KB50 views
Click for full-size image (pitfall2.JPG)
10.8 KB40 views

Last edited by Jason D; 29-09-2010 at 12:09 PM.
Reply With Quote
  #12  
Old 29-09-2010, 11:51 AM
Jason D's Avatar
Jason D (Jason)
Registered User

Jason D is offline
 
Join Date: Aug 2009
Location: California USA
Posts: 117
Back to the 1.25" versus 2" autocollimators, the attached photo shows the image off a 1.25" Astrosystem autocollimator versus a 2" Catseye autocollimator.
Attached Thumbnails
Click for full-size image (2_vs_1_25.JPG)
19.5 KB79 views
Reply With Quote
  #13  
Old 29-09-2010, 09:39 PM
richardda1st (Richard)
Registered User

richardda1st is offline
 
Join Date: May 2009
Location: Melton, Victoria, Australia
Posts: 372
Yes well I'm definately going for the 2", thanks Jason & qld. The larger target area shown in those pics will be worth the extra few dollars.
I have just been offered a test run using the 2" catseye, so I'll wait till then.

Richard

ps. I hope I'm not the only one who finds all the different combinations and naming style on the catseye page very confusing.
Reply With Quote
  #14  
Old 29-09-2010, 09:53 PM
erick's Avatar
erick (Eric)
Starcatcher

erick is offline
 
Join Date: Dec 2006
Location: Gerringong
Posts: 8,532
Richard

Have you read the various Cloudy Nights threads on collimation and tools?
Reply With Quote
  #15  
Old 30-09-2010, 03:50 PM
NeilW
Registered User

NeilW is offline
 
Join Date: Feb 2006
Location: Adelaide
Posts: 296
Quote:
ps. I hope I'm not the only one who finds all the different combinations and naming style on the catseye page very confusing
No, I find them confusing too, Richard.

Can anyone tell me if using a Catseye whether it's necessary to replace your primary centre spot with one of theirs, or will it work with the standard spot that the scope came with?

Thanks,
Reply With Quote
  #16  
Old 30-09-2010, 03:55 PM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
Quote:
Originally Posted by NeilW View Post
No, I find them confusing too, Richard.

Can anyone tell me if using a Catseye whether it's necessary to replace your primary centre spot with one of theirs, or will it work with the standard spot that the scope came with?

Thanks,
Not necessary to replace your center spot but the cateye triangular shape helps to point to the collimation screws to tweak. They actually have a new profile now which is even better for superimposition of the spots and works well with the double pupil A/C.
Reply With Quote
  #17  
Old 30-09-2010, 04:00 PM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
Quote:
Originally Posted by richardda1st View Post
Yes well I'm definately going for the 2", thanks Jason & qld. The larger target area shown in those pics will be worth the extra few dollars.
I have just been offered a test run using the 2" catseye, so I'll wait till then.

Richard

ps. I hope I'm not the only one who finds all the different combinations and naming style on the catseye page very confusing.
You need the sight tube (TELECAT XL) to center your secondary under the focuser.
Then the cheshire (BLACKCAT XL) to align the primary.

Then the auto-colimator (INFINITY XL/K) to tweak the secondary orientation and tilt.

Of course it is an iterative process. Read thorougly the link to the PDF Jason posted and have a look at Vic Menard's primary offset technique. It's important to understand why it works.
Reply With Quote
  #18  
Old 30-09-2010, 06:08 PM
Jason D's Avatar
Jason D (Jason)
Registered User

Jason D is offline
 
Join Date: Aug 2009
Location: California USA
Posts: 117
For those who are interested to understand the autocollimator in details, you can read my thread at cloudynights
http://www.cloudynights.com/ubbthrea.../o/all/fpart/1
Read at least the first page of the thread
Bear in mind that understanding the details included in the first page of the above thread is NOT a requirement to use the autocollimator.
Jason
Reply With Quote
  #19  
Old 30-09-2010, 06:52 PM
richardda1st (Richard)
Registered User

richardda1st is offline
 
Join Date: May 2009
Location: Melton, Victoria, Australia
Posts: 372
I have read a few articles & forum posts regarding the autocollimator, I'm convinced that the AC is the best tool to use at the moment. I understand the basic concept but for the fine detail that Jason has explained is not so easy.

I assume (ass again) all will fall into place once I get my hands on one of these tools.

Richard

ps. Thanks Neil I'm glad I'm not alone in my confusion.

Some web pages are just not as easy as others.
Reply With Quote
  #20  
Old 01-10-2010, 05:32 PM
Jason D's Avatar
Jason D (Jason)
Registered User

Jason D is offline
 
Join Date: Aug 2009
Location: California USA
Posts: 117
Quote:
Originally Posted by multiweb View Post
They actually have a new profile now which is even better for superimposition of the spots and works well with the double pupil A/C.
It is called the HotSpot
Attached Thumbnails
Click for full-size image (white_hotspot.jpg)
69.8 KB39 views
Click for full-size image (blackcat.jpg)
54.2 KB29 views
Click for full-size image (xlk_central.jpg)
54.3 KB35 views
Click for full-size image (xlk_offset.jpg)
58.3 KB43 views
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 01:07 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement
Testar
Advertisement