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How to Collimate your Newtonian

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#101 Vic Menard

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Posted 06 June 2012 - 10:58 AM

I have a question for Vic, I also have an f/4 scope, mine with a Baader MPCC (multi purpose coma correcter), when collimating, do I take the MPCC out or can it be done with it in?? What difference does it make if any and what is the recommendation for faster coma corrected scopes?

I use a Paracorr2 with my f/4 scope. I always remove the Paracorr before I align the scope. I've verified my original Paracorr1 alignment (it's a weak Barlow) with my regular alignment and there was no change in the critical primary mirror alignment. I haven't actually checked the Paracorr2 yet, but I expect to find similar results as the scope's optical performance is excellent.

I can't tell you how the MPCC will behave, but if it does change the scope's axial alignments and you can't resolve the error (e.g., different threaded positions, different adapters, etc.)--and the error impacts the scope's performance--I would have it replaced.

Visual and imaging applications will place different demands on the axial alignments and the mechanicals. The smaller aperture astrographs can be difficult if you're pushing the performance envelope.

#102 JoeM101

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Posted 06 June 2012 - 11:58 AM

I have a question for Vic, I also have an f/4 scope, mine with a Baader MPCC (multi purpose coma correcter), when collimating, do I take the MPCC out or can it be done with it in?? What difference does it make if any and what is the recommendation for faster coma corrected scopes?

I use a Paracorr2 with my f/4 scope. I always remove the Paracorr before I align the scope. I've verified my original Paracorr1 alignment (it's a weak Barlow) with my regular alignment and there was no change in the critical primary mirror alignment. I haven't actually checked the Paracorr2 yet, but I expect to find similar results as the scope's optical performance is excellent.

I can't tell you how the MPCC will behave, but if it does change the scope's axial alignments and you can't resolve the error (e.g., different threaded positions, different adapters, etc.)--and the error impacts the scope's performance--I would have it replaced.

Visual and imaging applications will place different demands on the axial alignments and the mechanicals. The smaller aperture astrographs can be difficult if you're pushing the performance envelope.


Thanks Vic,

I will try collimating with both Catseye tools and the Howie Glatter combo, then pop in the MPCC and keep my fingers crossed that nothing changes with the laser... hopefully they don't, the Baader only costs 180 as opposed to 500 for the TV.

clear skies

#103 fender2547886

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Posted 14 June 2012 - 11:53 AM

I have a question for the group. I have an AT 12.5" Imaging newtonian and am using a hutech sca laser collimator.
1-I sent the laser on the primary by adjustung the secondary screws.
2-I then adjust the primary mirror by adjusting the three screws at mirror cell.
3-I then double check the centering of the primary and everything is perfect until....

#104 fender2547886

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Posted 14 June 2012 - 11:58 AM

I have a question for the group. I have an AT 12.5" Imaging newtonian and am using a hutech sca laser collimator.
The scope is mounted on a Parallax hd150 mount with the OTA pointing about 10 degrees off the horizon. The focuser is a large format Moonlite bolted and reinforced with steel washers on the inside to keep it firmly secured. The laser collimator is seated squarely in the focuser and tightened in place.

1-I center the laser on the primary by adjusting the secondary screws.

2-I then adjust the primary mirror by adjusting the three screws at mirror cell.

3-I then double check the centering of the primary and everything is perfect until....

4-I leave the laser collimator on and untouched in teh focuser and move the scope from 10 degrees off the horizon to 20, 25, 30 60 degrees and I can watch the laser collimation move from dead center on the collimator to completely off the collimator!

I have tightened the secondary and there seems to be no loose parts. Any help? or Am I being too critical?

#105 mwtse

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Posted 14 June 2012 - 05:45 PM

Is most likely due to bending/twisting of varies part of your scope structure. Usually, the spider which support your secondary is made of the thinest metal so it is the first thing to look at. Look at the dot on the primary, if that dot drifted at different point angle of your scope (up and down), that usually means you have to tighten the secondary mounting screw more so that the spider is under tension. But be care that your OTA tube can withstand the great force.

For my scope, the red dot at primary mirror drifted for about 5 mm maximum, when I adjust the secondary screw again so that the red dot is back to centre on the primary after moving the scope up or down, the collimation was back to centre, that means the primary mirror of my scope is more or less not moving. But your scope may be different.

#106 De Lorme

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Posted 30 June 2012 - 04:02 PM

Hi, I need some help in collimating my 10" AT f/3.9 reflector. I centered the secondry under the focuser. Next I
Used the 3 outer screws to center the primary tabs into the secondary mirror. Last I centered the Primary using the primary ajusting nobs to the secomndary mirror. When I put the cross hair chelshire into the focuser the cross hairs do not line up with centered primary. I can center the secondary to the cross hair and than center the primary to the cross hair but when I do there's ony 2 tabs in the field of view. Am I getting the full use of the mirror when I do it this way. Is it better to just center the 3 tabs and then center the primary{with it's ajusting nob's}, and then do a star test? Thanks for your advice. De Lorme

#107 JoeM101

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Posted 30 June 2012 - 04:07 PM

Good question, i had a similar issue, could only see 2 of the three primary tabs when collimated with both HG laser and catseye tools. Jim from catseye said i need to realign my secondary... sold the scope but still curious as i'm waiting on a dob now and would like to know in case i run into the same issue on the new scope

#108 ManojK

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Posted 19 July 2012 - 01:25 PM

Hey guys, this has probably be answered in this long thread, but I am looking for some pointed advice. I have an Orion f/4 8" newtonian that I use for astrophotos. The collimation has always been the hardest part for me. Currently I have a Hotech 2" self centering laser, 1.25" collimation cap and a 1.25" crosshair sight tube. Centering the secondary in the focuser tends to be very hard for me because the sight tube does not show the whole secondary regardless of the position in the focuser. Would the collimation cap with the focuser racked in all the way work for this purpose? Even then is it just subjective visual estimation or are there tools that will quantitatively tell me if the secondary is centered to the focuser. Would the secondary centering actually affect collimation or just the illumination point on the chip (not centered)? Given the tools I have would it be worthwhile for me to invest in the catseyecollimation set of tools (they are pricey at 300 for all 3) and would they aid me better with the centering of the secondary and aligning the two axes?

The problem is worse because after collimation I use a MPCC in the train and I can't figure out whether the problems are because of the spacing between the MPCC and CCD or because of collimation or both. I have attached a 60s capture so you can evaluate how far off I am (either in terms of collimation or the spacing)

Attached Thumbnails

  • 5325158-M101Coma.jpg


#109 TopHouse

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Posted 01 August 2012 - 05:15 PM

Hello Joe,

Thank you for the kind words.

if anyone is interested in watching a video on collimation, this guy (Dion) isn't so bad Advanced Newtonian Collimation he has a way about him


Unfortunately, references to the above video have been popping up in various forums. It is unfortunate because Dion makes a serious misleading claim. He discredits laser collimators by stating that laser collimators “lie.” Dion made the mistake of expecting laser collimators to be used to center/round the secondary mirror under the focuser. Unless a laser collimator is used with a holographic attachment, it is not expected to center/round the secondary mirror under the focuser.

Jason


Jason, i agree that he goes a little far with regards to laser collimation in saying that they lie, hence my comment that it's a tad simplistic and doesn;t cover all the points. He does say that the laser is not intended to line up your secondary though, even though with a holographic attachment, as you stated, you certainly can... but anyhow, i wanted to see if you or any of the others, Vic? Nils?, Alexis (sixela).. would have a gander at a thread i started with regards to using a coma correcter while collimating and give some feedback as Howie has stated you guys (ray-tracers lol) were probably able to give some insight

The thread: Help Collimating an F/4 with coma correction

Since Vic is also using a coma corrected F/4, he may be able to shed some more light on this

thanks


As the person in question, it seems Jason makes a habit of circulating around various forums making claims that I make misleading statements and various other derogatory claims. Since he chose to do this in public forums, and since he did not see fit to pass comment on the available youtube messaging facility or indeed through my own site, I feel it is only fair that in retrospect, I be allowed to defend myself in the same medium.

The simple fact is that the instructions for almost every single point laser collimator on the market give a procedure for centering the secondary that involves adjusting rotation and the tilt/skew grub screws to center the single point in the middle of the donut on primary. This is WRONG and I stated as such, using this method, a rotation can be apparently corrected using a skew adjustment. Therefore, the single point laser, when used for secondary adjustment in this way LIES!

Strange that in a number of his derogatory attacks on myself in various forums have also resulted in him contradicting himself!

So apparently, according to Jason, what I said was wrong, yet he states in many posts that a single point laser is not the tool for centering a secondary! Hmmmm, go figure!

Apologies to the mods for this, but you allowed the slurs to be posted on the forum so it is only fair that I have the right of redress.

I do have personal issues with Jason and we have had our run in's before, however I don't go around slurring him on public forums, and I do feel that an amount of this is down to this 'personal issue'. So Jason, if you want to have a pop, please feel free to do it to may face, directed 'at' me as opposed to on public forums. This is my last word on the matter on this forum.

regards,

Dion

http://www.astronomyshed.co.uk

#110 CatseyeMan

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Posted 01 August 2012 - 07:51 PM

...The simple fact is that the instructions for almost every single point laser collimator on the market give a procedure for centering the secondary that involves adjusting rotation and the tilt/skew grub screws to center the single point in the middle of the donut on primary. This is WRONG and I stated as such, using this method, a rotation can be apparently corrected using a skew adjustment. Therefore, the single point laser, when used for secondary adjustment in this way LIES!..


Hi Dion,

I suspect there is a conflict of semantics at play here. In most CN forum discussions about the adjustments of the Secondary, there are three distintly different collimation phases and referencing terminologies:

1) "CENTERING" of the Secondary is the process of making the necessary adjustments (via the central stalk and spider vane attachments and/or focuser base relocation/shims) in a plane perpendicular to the focuser axis to center the Secondary directly beneath the focuser to symetrically capture the image light cone. A simple "beam' laser most certainly WILL NOT aid in this endeavor; the sight tube or "holographic pattern" laser are the tools to use.

2) "PRESENTATION" optimization involves the process of adjusting the tilt and rotation of the Secondary to eliminate Secondary "skew" and facilitate as near a circular projection of the elliptical surface to the focuser as possible. A simple "beam' laser most certainly WILL NOT aid in this endeavor; the sight tube or "holographic pattern" laser are the tools to use. There is only 1 combination of Secondary tilt and rotation that will be optimum for presentation.

3) "AXIAL ALIGNMENT" of the Secondary is the process of adusting the tilt/rotation of the Secondary to aim the focuser axis at the center of the Primary. A beam laser or cross-hair sight tube WILL facilitate this. There are an infinite number of combinations of Secondary tilt and rotation settings that will achieve focuser axis alignment. In this regard, unless the beam laser is itself internally out of alignment, regardless of the centering and presentation condition, it does not "lie" - it clearly demonstrates an accurate response to a selection of one of those setting combinations. If the beam strikes the center of the center spot, a coarse axial alignment has been accomplished and it's usefulness stops there.

The bottom line is that focuser axial alignment CAN be achieved irregardless of the state of "centering" & "presentation" condition of the Secondary, but that said, it's prudent to implement centering and proper presentation, BEFORE focuser axial alignment is undertaken.

If there are indeed beam-laser instructions out there that infer Secondary "centering" (and/or "presentaton") can be accomplished with that tool, it's the procedure writer who is mis-informing the user, not the laser.

#111 Jason D

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Posted 01 August 2012 - 09:41 PM

For the record, I only criticized your misleading message in my replies to others who innocently tried to perpetuate your misleading message about how laser collimators “lie”. I never made an attempt to start a thread or start a subject criticizing your video – I only replied to other posts and I will continue to do so. My participation in several forums pre-dates your video and has nothing to do with you. I do stand by what I stated about your misleading message and by my opinion of your collimation expertise – lack of.

The simple fact is that the instructions for almost every single point laser collimator on the market give a procedure for centering the secondary that involves adjusting rotation and the tilt/skew grub screws to center the single point in the middle of the donut on primary. This is WRONG and I stated as such, using this method, a rotation can be apparently corrected using a skew adjustment. Therefore, the single point laser, when used for secondary adjustment in this way LIES!

You do not seem to understand the difference between focal plane tilt adjustment and the 100% illumination field optimization adjustment. Both adjustments are made exclusively by the secondary mirror. Quality single laser collimators eliminate focal plane tilt error. They are not meant for optimizing the 100% illumination field. However, a laser collimator with a holographic attachment is capable of optimizing the 100% illumination field. An introduction of a small secondary mirror rotational error can be compensated for by a secondary mirror tilt error to eliminate focal plane tilt error – not the 100% illumination field error. That is what you have demonstrated in your video. In your video, you were only interested in optimizing the 100% illumination field. Here is an animation that I put together years ago. In each frame, the single laser beam hits the primary center then bounces back to the source. That is, each frame eliminates the secondary focal tilt error but only one frame eliminates the 100% illumination field error.
Posted Image

You can’t continue making misleading claims about single laser collimators. They do not “lie”. They are not meant for the 100% illumination field optimization. This is an old fact that has been communicated by Vic Menard and others for years. You did not make any new discoveries. You just took a known fact about single laser collimators then repackaged it as a new discovery under the misleading “laser lie” title.

Jason

#112 Jason D

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Posted 01 August 2012 - 09:42 PM

If there are indeed beam-laser instructions out there that infer Secondary "centering" (and/or "presentaton") can be accomplished with that tool, it's the procedure writer who is mis-informing the user, not the laser.


Well-said, Jim :waytogo:

#113 TopHouse

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Posted 02 August 2012 - 06:15 AM

You can’t continue making misleading claims about single laser collimators. They do not “lie”. They are not meant for the 100% illumination field optimization. This is an old fact that has been communicated by Vic Menard and others for years. You did not make any new discoveries. You just took a known fact about single laser collimators then repackaged it as a new discovery under the misleading “laser lie” title.

Jason


That would be the contradictions I'm talking about! Apparently I'm now claiming new discoveries as well! As I said Jason, you want to take it up with me in private, feel free!

Dion

#114 Jason D

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Posted 02 August 2012 - 09:10 AM

you want to take it up with me in private


Dion, you are clearly taking this matter way too personal. Lighten up. I have no interest in pursuing this in private. As I have stated, I never started a thread or a subject criticizing your video. I only provided a fair balance whenever others tried to perpetuate your misleading claim. I believe I am entitled to post replies to other posts expressing my opinion and I will continue to do so. If you disagree with my replies, you are also entitled to reply to my posts in this forum and others to express your opinion. As long as we stay on the subject, I do not mind debating it.

Many beginners who watch your video will avoid purchasing single laser collimators because you told them that these tools “lie”. This is unfair. Quality laser collimators when used properly are excellent collimation tools and easy to use. Why couldn’t you explain the proper use of single laser collimators by clarifying that they are not meant for centering/rounding the secondary mirror under the focuser? That is it. Why did you use the word “lie”? The issue is not with the tool but rather with the improper usage of the tool.

Jason

#115 David Pavlich

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Posted 02 August 2012 - 10:24 AM

OK, gang...let's get back on topic.

David

#116 Vic Menard

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Posted 02 August 2012 - 10:34 AM

...The simple fact is that the instructions...(are)...WRONG. Therefore, the single point laser, when used for secondary adjustment in this way LIES!...

I don't think anyone will argue the point that the instructions provided with some economy laser collimators are often so simplified that the user will be hard pressed to achieve a reliable collimation. Check the one-step alignment procedure in the product description here.

I think the problem is the conclusion that the laser somehow "lies". Used properly, the outgoing beam of a simple thin beam laser represents one thing--the focuser axis. As the focuser axis is one of the two axes that will be assessed and corrected when collimating a Newtonian, and it's one of the two alignments that have a defined performance tolerance, it's an important axial alignment. If the internal laser alignment is good and the laser/focuser registration is consistent, there's no way the laser can "lie"--the outgoing beam is the focuser axis.

Many users also adjust the primary mirror tilt to align the return beam back to the laser target (often visible in a side "window"). But the return beam is simply the reflection of the focuser axis! If the focuser axis isn't precisely aligned to the center of the primary mirror first, using the return beam to adjust the primary mirror tilt will misalign the critical axial collimation.

A precision thin beam laser collimator coupled with precision mechanicals and used properly is a valuable tool for axial alignment assessment and correction.

I suspect there is a conflict of semantics at play here.

Yep.

1) "CENTERING" of the Secondary...(and)...2) "PRESENTATION" optimization...A simple "beam' laser most certainly WILL NOT aid in this endeavor; the sight tube or "holographic pattern" laser are the tools to use.

While I agree with this statement (and prefer a good sight tube for the job), there are still some users (and at least one manufacturer) who suggest using a secondary mirror reference spot to facilitate the alignment of the front end geometry with a simple thin beam laser. There are many pitfalls, complicated measurements, and convoluted "dead ends" associated with the procedure, but it has its following.

3) "AXIAL ALIGNMENT" of the Secondary is the process of adusting the tilt/rotation of the Secondary to aim the focuser axis at the center of the Primary...

Again, semantics--the secondary mirror is an optical flat and has no axis--although it reflects both axes when assessing and correcting the axial alignment. As described, the alignment is "AXIAL ALIGNMENT" of the Focuser...

Since secondary mirror adjustments affect both axes, changing the focuser axis this way also changes the primary mirror axis, which is why primary mirror axial alignment is always the last step.

The bottom line is that focuser axial alignment CAN be achieved irregardless of the state of "centering" & "presentation" condition of the Secondary, but that said, it's prudent to implement centering and proper presentation, BEFORE focuser axial alignment is undertaken.

:ubetcha:

If there are indeed beam-laser instructions out there that infer Secondary "centering" (and/or "presentaton") can be accomplished with that tool, it's the procedure writer who is mis-informing the user, not the laser.

Although their numbers are dwindling, there are still advocates--some use a secondary mirror reference spot, some don't...

This exchange reminds me of a quote by Wolfgang Pauli (after reading a young physicist's paper):

"This isn't right, this isn't even wrong."

#117 Nils Olof Carlin

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Posted 02 August 2012 - 02:44 PM

One crucial aspect of collimation is knowing what each tool will show, and what it won't show - in order to use the right tool to see what you need to know at any step.

Having decided that your primary center spot is centered accurately enough, as is your spider, a good first step is to use a peephole tool (any kind - just to give a centered perspective) and turn your secondary until it looks correctly rotated, and leave it there (checking later that it remains so!). Then tilt it to get at least somewhat close to the right tilt (laser, crosshairs sight tube - if not, the next step can be misleading). Next check the placement (in-out the tube, sideways) and correct if necessary (sight tube, combination tool, holographic laser - in a pinch, you can always later check that the primary and secondary are concentric) - if you need to adjust, repeat the sequence.
Now you can fine-adjust the tilt of the secondary (laser, crosshairs sight tube, autocollimator CDP), before last step (=tilting the primary). It is this step that Dion just omits (should have been described at the end of video 8, or beginning of 9, I believe), claiming that the (narrow-beam) laser isn't useful. It is indeed perfectly good, once the rotation of the secondary is known to be correct (and that is what I understand to be the gist of Jason's criticism).

It is easy to verify the shape and outline of the fully illuminated field (I have described how in a previous thread) - if circular (or possibly elongated or compressed along the tube - but not obliquely!), the rotation is OK.

Though not nearly as critical as the primary's axis, the focuser axis (adjusted by tilting the secondary) should be reasonably close - not to confuse the subsequent collimation of the primary, if for no other reason.

BTW, the video #9 well illustrates the potential problems of putting a side-window laser into a Barlow - we have discussed it in earlier threads. The reflection of the laser in the concave lens of the Barlow gives a quite bright spot on the center of the laser face, possibly large and bright enough (as shown) to confuse the reading of the spot's perforation shadow. Also, we mentioned the potential offset mechanism due to the diverging shadow. This may not be serious, but turning the laser 180 deg ought to reveal any significant problem here, I should believe.

Nils Olof

#118 S. Fritts

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Posted 24 August 2012 - 10:57 AM

I am new at this and it is way too complicated for me. Could someone post a simple explaination for this procedure or am I out of my element even being here?

Steve

#119 Starman1

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Posted 24 August 2012 - 07:24 PM

I am new at this and it is way too complicated for me. Could someone post a simple explanation for this procedure or am I out of my element even being here?

Steve

Send me a private message with your email and I'll send you my tutorial.
Just bear in mind there are only a few steps:
1) move secondary up or down in the tube until it's centered under the focuser (doesn't have to be perfect). Don't do again until you remove the mirror for cleaning.
2) rotate the focuser around its center axis until it appears round to the eye (doesn't have to be exact).
3) Adjust tilt of secondary until centermarker on primary lines up behind crosshairs or until a laser points directly at the center of the primary's center marker. Be as exact as you can.
4) Adjust tilt of primary until image of center marker on the primary is in the center of a cheshire or centered around the hole in the bottom of a barlowed laser. Be as perfect as you possibly can be. This one is the most critical adjustment.

Though explanations can get a lot more long winded, that's about it. If an autocollimator tool is used, there is a fifth step, but it is pretty much refining the adjustments made in steps 2-4.
It helps to see illustrations of what you'll see with the tools, so send me that message.
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#120 CatseyeMan

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Posted 25 August 2012 - 05:50 AM

I am new at this and it is way too complicated for me. Could someone post a simple explaination for this procedure or am I out of my element even being here?

Steve


7 Steps for Perfect Collimation

#121 vman69au

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Posted 27 August 2012 - 03:21 AM

Hello,

Hoping someone may be able to help me.

I just took possession on my first reflecting telescope ( an f3.8 Orion Optics AG-10). Have been a refractor guy for a while now.

I have the cats-eye collimation tools. The Telecat XLS site tube/Cheshire cobo and the infinity XLK collimator. ( one with central and offset pupil)

I have watched videos and followed instructions. I think I am reasonably close. Quite a learning curve I must say having never dealt with reflecting optics before.

Where I am at is as follows:

With the auto-collimator, looking through the center hole the hot dots are perfectly aligned. I then look through the offset hole each pair are not be perfectly aligned. If I get them perfectly aligned in the offset hole, they're not in the center hole.

To say another way, my radiation hotspot is centered in Cheshire and stacks are aligned in central view. Problem is in offset view they are not stacked . Once I adjust secondary to stack in offset view they are no longer stacked in central view and vice versa.

If I stack either central or offset with primary centered in Cheshire, my glatter laser puts laser dead center of the radiation spot.

I am just not sure why I cannot get offset AND central views to stack as per images and instructions. I have iterated back and forth between Cheshire for primary and Auto Collimator for secondary heaps of times.

Any suggestions what may be causing this and what I need to adjust ?


Thanks
Chris

#122 CatseyeMan

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Posted 27 August 2012 - 06:17 AM

Hello,

Hoping someone may be able to help me.

I just took possession on my first reflecting telescope ( an f3.8 Orion Optics AG-10). Have been a refractor guy for a while now.

I have the cats-eye collimation tools. The Telecat XLS site tube/Cheshire cobo and the infinity XLK collimator. ( one with central and offset pupil)

I have watched videos and followed instructions. I think I am reasonably close. Quite a learning curve I must say having never dealt with reflecting optics before.

Where I am at is as follows:

With the auto-collimator, looking through the center hole the hot dots are perfectly aligned. I then look through the offset hole each pair are not be perfectly aligned. If I get them perfectly aligned in the offset hole, they're not in the center hole.

To say another way, my radiation hotspot is centered in Cheshire and stacks are aligned in central view. Problem is in offset view they are not stacked . Once I adjust secondary to stack in offset view they are no longer stacked in central view and vice versa.

If I stack either central or offset with primary centered in Cheshire, my glatter laser puts laser dead center of the radiation spot.

I am just not sure why I cannot get offset AND central views to stack as per images and instructions. I have iterated back and forth between Cheshire for primary and Auto Collimator for secondary heaps of times.

Any suggestions what may be causing this and what I need to adjust ?


Thanks
Chris


Chris,

Typically imaging telescopes (with coma correctors removed for collimating) have a natural focal plane 1.5" to 2" above the focuser. For the autocollimator to perform accurately and consistently, its mirror must be at or near the focal plane; as such, I suspect you are experiencing reflection queue parallax registration error. Get yourself a 2" focuser Barrel Extender to place between the focuser drawtube and the autocollimator and see if that helps.

This CN forum discussion may also be of interest to you: Custom XLK; if so, contact me at flyj@catseyecollimation.com .

#123 Jason D

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Posted 27 August 2012 - 10:22 AM

With the auto-collimator, looking through the center hole the hot dots are perfectly aligned.

Do reflections P & 2 have similar size or is one larger than the other?
When collimation is reached, you are not suppose to see a stack via the central pupil but rather a solo center spot -- unless the AC mirror is greater than 5% focal length below the focal plane.
Jason

#124 vman69au

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Posted 28 August 2012 - 05:15 AM

Jason, reflection 2 was MUCH larger, by nearly 40% I could hardly make out 3 and could not see 4.

I used a 2" eyepiece extension tube tonight which lifted the autocollimator about 70mm higher than from where it was.

Amazing the difference. The hot spot reflections were crisp and focused and looked just like the picture on the catseye website. I was able to get the offset view with double stacked hotspots and central pupil with single hotspot (maybe a little fuzz from the other reflections detectable around the outside with very bright LED torch but for all intense and purpose central view showed only P1.

The cheshire confirmed everything centered as well. Took me less than 15 minutes. Compared with 3 hours last night and 3 night before with no result.

I would suggest with the number of these fast imaging newts coming on the market that instructions for the catseye tools have a warning about the focal plane as it makes a HUGE difference.

The extension tube does add some error though, so now I need to look at getting a new autocollimator with extension built in.

Thanks for the help gents. One thing that does bother me a bit though is after all of this the glatter laser is not dead center of the hot spot. Even though Cheshire view is in middle and autcollimator shows what it should its about 1mm off center.


#125 CatseyeMan

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Posted 28 August 2012 - 07:03 AM

...I would suggest with the number of these fast imaging newts comming on the market that instructions for catseye tools have a waning about focal plane as it makes a HUGE difference....


There IS an "IMPORTANT" heads-up note about this at the top of the first page of the instructions here, but yes, a stronger message (and alternative product offering) to imagers with the built-in offset focal plane issue needs to be addressed. Stay tuned!


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