How to use CATSEYE Collimation tools

[strongmanmike]

After recieving my ASA N12 F3.8 Newtonian Astrograph I needed a high quality and accurate method to precisely collimate the fast F3.8 optics, so I went with the CATSEYE range of passive collimatin tools.

I purchsed the following:

2.00"/15" Max.
TELECAT XL + INFINITY XL
COMBOSET PRO XL Kit


Which includes the TELECAT sight tube/cheshire tool and the INFINITY autocolimator.

While I wait for my FLI camera, collimating is a good thing to practise to fill in the time

I thought many on this group have Newtonians and might benifit from the instructions I have put at my web site describing how to use these tools?

http://www.pbase.com/strongmanmike2002/collimating_with_the_catseye

Everything looks text book but the proof will be in the pudding once I can test it with a large CCD chip at the focal plain :)

Cheers

Mike

[iceman]

Excellent, thanks Mike. I'm going to get a Catseye myself, to ensure perfect collimation. At the moment, my primary center spot ring (white circle ring binder) is not big enough and it's difficult to ensure perfect collimation.

Can you give me a link to exactly what you got? I know Anthony has the same, doesn't he?

[strongmanmike]

Get what I said I got above - this is the description direct from the CATSEYE web site.

Just tell Jim Fly at CATSEYE you want what Strongmanmike got :D

Yes Anthony uses the same

Best

Mike

[Starkler]

I have just the telecat (combined sight tube & cheshire) and i find it hard to see the alignment. I also have the white triangle instead of the reflective red.
The telecat doesnt allow enough light in.

Luckily I got the triangle centres with 1/4" centre hole and this does fit my old Synta cheshire well.

[skeltz]

Hi mike reckon thats what i will be getting for my newt that im going to make ,thanks for the info.
And whens your camera getting there....Have you got any hair left????

[strongmanmike]

LOL

Yeh, I have a few hairs left ...just!

FLI confirmed with me this morning that they hope to have my ProLine ready this week soooo fingers (double) crossed :-) The delay was apparently due to a back log of orders that built up because they announced the new ProLine a little too early. They have been flat out apparently but the production frenzzy should settle down once they catch up?

Mike

[iceman]

lol just at the Catseye site now, and who's picture should I see but Mr Mike Sidonio! You're everywhere! :)

[matt]

Mike (either one!)

Got a link to the Catseye site?:)

[iceman]

http://www.catseyecollimation.com/ceyeflr1.html

[matt]

Ta

[h0ughy]

OK Mike's! A Vixen R200SS F4 would need which "tools" to collimate it? I have had a look and confused me a little (only 2 brain cells, one for breathing...), which product/combination would you recommend?

[h0ughy]

OK I get his website hasnt been updated for a while , his email comes back as undeliverable?

[iceman]

I emailed him this morning and it didn't bounce?

[h0ughy]

was it this address flyj@catseyecollimation.com because what I got was this

Your message did not reach some or all of the intended recipients.

Subject:

The following recipient(s) could not be reached:

flyj@catseyecollimation.com on 21/03/2007 9:44 AM
The e-mail system was unable to deliver the message, but did not report a specific reason. Check the address and try again. If it still fails, contact your system administrator.
< mail1.ncc.nsw.gov.au #5.0.0 smtp; 553 Bogus helo NC006128. <http://unblock.secureserver.net/?ip=203.12.147.238>>

[strongmanmike]

Well for my ASA 12" F3.6 I got:

2.00"/15" Max.
TELECAT XL + INFINITY XL
COMBOSET PRO XL Kit

http://www.catseyecollimation.com/xl-csp640.jpg

Mike

[catseyeman]

If you're still having trouble :( , try my personal email at: jpfly@comcast.net

Jim Fly
CATSEYE Collimation

[h0ughy]

Thanks Email sent

[Don Pensack]

I will e-mail to anyone interested a step-by-step procedure for collimation with pictures using the Catseye tools.
Send me an e-mail at pensack1@excite.com
and I'll bounce it right back.

[iceman]

Hi Don.

I'd be happy to include it as an article on the IIS website - would you mind emailing it to me?

[Don Pensack]

Mike,
After the first issue of Astronomy Technology Today comes out.
Don

[iceman]

np Don.

[Don Pensack]

Mike,
send me your e-mail address and I'll send you the article.
ATT is going to press.
Don

[h0ughy]

OK I have received my Catseye, now to set everything up

[Don Pensack]

Houghy,
My article on how to use the tools is in the articles section, entitled "Collimation and the Newtonian". Let me know if anything is unclear after you read it.
Good luck.
Don

[h0ughy]

Thanks Don:thumbsup:

[wavelandscott]

I have now joined the "Catseye Club" having picked up a "Strongman Mike recommended Combo Set" during my recent trip to the USA...Jim Fly was good to deal with via e-mail with good solid communication through the whole process.

I have not had a chance to triangle center spot my mirror yet (I just arrived back home in Australia this morning)...Having said that, the material included looks wonderfully made. I can't wait to try it all out.

Cheers All!

[rodroger]

I have found Jim Fly very friendly and helpful, I have been in contact with him by email myself. I just recently purchased a Cat's Eye collimating kit for a 1.25" focuser - 6" scope, even though he does not supply autocollimating tools for the 1.25" he recommended another company on the web that does, which was cool of him.

http://www.astrosystems.biz/coltlsm1.htm

I previously purchased one of his chairs, Catsperch Pro, in kit form (plans & fittings only), extemely fast postage from the states, 10 days. I only had to wait a couple of days for the order of the chair to be sent out, but had to wait about 10 days for the collimating kit to be posted out, must be very popular.

[rumples riot]

I have been using Cats eye collimation tools on my SDM for nearly 5 months now and found that the collimating is the easiest I have ever performed. The collimation is very tight and only requires just the odd tweek with the barlowed laser to get the collimation very tight for imaging or viewing. Everything Jim's site says about his tools is 100% correct. The jupiter image on my SDM Blog was partly the result of the tight collimation obtained by this system.

So if you are looking for an endorsement to Jim's product I am happy to confirm its worth. Buy the full kit and you will never look back.

[Don Pensack]

You should try his autocollimator. It can tweak the system tighter than any laser/barlowed laser can. In fact, the accuracy is so high that mechanical errors such as sag can show up in the autocollimator image. Though not critical on longer focal lengths, at f/5 and below, the autocollimator is a critical part of achieving the necessary accuracy in collimation.

The autocollimator will tweak the laser collimation instead of the other way around.

PS. "Tweek" is a product I haven't seen since the '70s. It was used to clean/seal electrical connections between patchcords and audio equipment.

Don

[rumples riot]

Don, I have the 2" triplepack, that includes the autocollimator. There is still room for some tweeking with a barlowed laser even after using the entire collimation kit.

[Don Pensack]

An autocollimator provides an order of collimation accuracy well beyond that of a barlowed laser. Once collimation has been achieved with an autocollimator no further collimation adjustment can be achieved with a barlowed laser unless the collimation has drifted off. A barlowed laser is, essentially, the same as a cheshire (the Catseye BlackCat), and the autocollimator can achieve a better collimation than either a sight tube or a cheshire.

So I'll go over a way of using the autocollimator that you might not be familiar with. Some day an inventor may come up with a more accurate collimator, but today it's the top of the heap. If an autocollimator shows the scope to be perfectly collimated, distrust your other tools.

After using the sight tube and cheshire and getting it as accurate as you can, the autocollimator will show the 4 reflected images of the centermark to be not completely perfectly "stacked" into one image. Which mirror do you adjust? How do you know what to do to make the 4 images perfectly stacked?

Reach down and miscollimate the primary by turning one of the collimation screws (I recommend the top screw) backwards or forwards about 1/4 turn.
In the autocollimator, the 2 reflected centermarks that are attributable to the primary will move away from the center of the field to the edge of the field, leaving the two images from the secondary still nearly stacked.
This is known as the "Carefully Decollimated Primary" protocol.

Using the screws on the secondary, carefully, and perfectly, stack the two images that are still nearly stacked in the center. You will find that doing so also brings the two decollimated images in from the edge slightly.

Then, using the primary collimation screw you moved, reverse the decollimation to bring those two images back to the center and stack them on the already stacked image from the secondary. You may find, as I always do, that to perfectly stack the two images from the primary requires adjusting more than just the collimation screw you decollimated.

After a little practice at this, all 4 images will be perfectly stacked and appear as one image with a slightly fuzzy edge.

Why the fuzzy edge? Because the differences in focal length the 4 images are seen cannot be simultaneously focused by the human eye.

This collimates the scope to a point 7 focal lengths out on the central optical axis, a multi-pass collimation that is not achievable by any other tool.
If any other tool shows the scope to be out of collimation at this point, there is something wrong.

What could be wrong if the other tools still show miscollimation?

Some possibilities:
1) misregistration. If the collimation tools are not tightened in place (despite what Jim Fly advises, all collimation tools need to be tightened in place to avoid misregistration caused by slop between the tool and focuser), then each individual tool can sit slightly askew in the focuser and this would make acieving a perfect stack with the autocollimator impossible. The AC is so sensitive that slight differences in sag in telescope components will decollimate the stacked 4 images. Some focusers aren't cut squarely on top of the drawtube. Others have drawtubes that aren't concentrically drilled (up and down motion not coincident with the center line of the hole). There might be slop between the fit of the barlow and the focuser.
2) flexure/sag in some component. This can be secondary movement because the spider isn't tight enough, or actual movement of the focuser drawtube in the focuser, or movement of truss tubes at either end, or sag in the truss tubes, or movement of the primary on its springs.
3) inaccurate tools. The tools can be non-round, so that putting the tool in ten times will get ten different results. Even your autocollimator may be misregistered and the perpendicularity of its internal mirror may be suspect. This is unlikely with a Catseye AC, but it can't be ruled out if rotating the AC in the focuser causes the stacking to change. With the exception of Glatter, many lasers aren't particularly round, I've found.

The gist of all this is that the AC should be able to do a final tweak (note spelling--it's not spelled with a double e) of collimation that goes beyond that accomplishable with any other tool, and which agrees with all the other tools.

And if you use a coma corrector (such as the TeleVue Paracorr), the tolerances for collimation tighten to 1/6th what they are without one, so achieving excellent collimation becomes even more important.

I'm not sure why you find the scope incompletely collimated with the barlowed laser AFTER using an AC, but I hope the above protocol will help in using the AC. I'll have to think about what other issues might be at play.

Best to you,
Don

[catseyeman]

Don,

We've had this discussion before on CN but here's another take here. ;)

I contend that viewing with an eyepiece slightly skewed (by focuser screw tightening) in a "collimated" focuser axis may be less detrimental that than the focuser axis being mis-collimated from the getgo by using a skewed (screw-tightened) autocollimator.

The objective in the adjustment of the tilt/rotation of the Secondary via merging of the multiple reflections in the A/C is to "aim" the focuser axis at the center of the Primary. For clarification, my advice for choosing non-tightening of focuser set screws is in the context of a constant, repeatable "registration" being readily accomplished by maintaining contact of the A/C tool flange against the end of the focuser drawtube with one's hand. Assuming the plane of the drawtube end is orthogal to its axis, axial collimation accomplished in this scenario insures that the diagonal is directing the focuser axis "exactly" at the Primary center. Any "skewing" of the A/C tool (via setscrew tightening) prior to starting the A/C protocol in effect "tilts" the A/C mirror away from orthogonality and defeats this objective.

In the case of an inverted focuser (gravity and inconvenience preventing practical pressure against the drawtube lip), the compromise is to use only 1 of the focuser setscrews to in effect cause the focuser axis to be parallel with the drawtube side (and its axis).

Readily admitted, this is an "intuitive" conclusion on my part as I haven't the mathematical "proof" of this argument. Perhaps this is one for Nils Olof to tackle (don't know if he subscribes to IIS)

Jim

[bird]

All,

I use the catseye collection of gizmos to collimate, works better than anything else I've tried, and has the great advantage that there is no guesswork required anywhere.

But there is one part of the process that always annoys me - with the autocollimator I can clearly see a difference between (a) holding it in by hand flat against the focusser, and (b) after tightening the two focusser screws to lock it in place.

There's just enough slop in the system for the autocollimator to tilt a bit. This is annoying, cause after I collimate I will be putting a barlow+camera in the focusser and I'm never sure that it retains the collimation.

I'm seriously planning to replace the 2-screw retention mechanism on my focusser with something much better, probably a screw-down arrangement that pulls the EP against the top of the focusser.

Anyway, I've come to the conclusion that the collimation is still "very close" to correct, even with a bit of movement there.

regards, Bird

[Don Pensack]

Jim,
I agree about tightening only one setscrew on the tool. You want the tool to be pressed into a linear contact with the wall of the focuser drawtube, just like the eyepiece. I'm lucky because my Catseye tools fit so tightly in my focuser they have to be twisted into the drawtube--tightening the setscrew makes no difference in collimation.
But in those focusers with a little more slop, I don't think it's practical to maintain a constant inward pressure on the tool to keep it seated in the focuser (and not tip due to gravity). And, as I've commented, I've seen one too many focusers not cut squarely at the top (and, quite recently, a focuser with only the top 3/8" of the drawtube having 2" I.D. and the rest about 1/16" larger!!!).
I like the idea of pressing the tool into a linear contact with the drawtube so it points exactly the same direction as the drawtube. Of course, this won't work if the hole in the drawtube isn't concentric and colinear with the O.D. of the drawtube, but that's a defective focuser anyway, and you shouldn't plan for that.
I guess my point is that there is a lot of slop in the typical telescope system, and leaving the tool loose just adds another bit of sloppy tolerance. I think repeatability demands a slight tightening of the setscrew in most applications. Bird's post just reinforces my thinking on that subject.