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Cateye Autocollimator

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#1 hungerford

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Posted 10 June 2013 - 12:49 AM

Hi,
I have invested in an autocollimator but unfortunately I am a little bit dim and I cannot understand and the various guide I found on the net don't help me.
Can anyone point me in the direction of a tutorial for beginners.
Thank you
Vince

#2 Jason D

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Posted 10 June 2013 - 12:53 AM

Did you get the Infinity XL or the XLK?
Did you attempt to follow Catseye provided steps? If yes, which steps sounded confusing to you?
Can you tell me how you are currently using it -- the steps your are following.
Jason

#3 rlmxracer

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Posted 10 June 2013 - 01:13 AM

Try this video http://youtu.be/Vj12cx3tnsM
I had to watch it a few times and then it all clicked. I have the 2 pupil XLK. I actually use the method they show at the end of the vidio in which I use the offset pupil and a 2" cheshire.

#4 hungerford

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Posted 10 June 2013 - 12:51 PM

Hi,
Thank you for the info. I am at present using a friend XLK collimator as I was so impressed with the collimation of his scope. Unfortunately at present he has gone on holidays for a month so I can't pick his brain. My XLK is on order.
What is confusing to me is that I find it difficult to identified what the reflections are and end up trying to stack the wrong reflection.
I started using a Cheshire eyepiece to do a quick collimation.
I then use a Farpoint 2" laser to make the collimation better.
Then I use the autocollimator and I get thing wrong as stated earlier.
If I try to image after the auto collimation the star are elongated and show a lot of coma.
I am sure it is me not doing the right thing.
Vince

#5 Jason D

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Posted 10 June 2013 - 03:48 PM

I still need more info.
What is the aperture size and focal length of your scope?
What kind of center spot you are using?
Can you take a photo from both XLK pupils and upload them into this thread?
Jason

#6 Starman1

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Posted 10 June 2013 - 05:21 PM

Try reading the part of this about the autocollimator to see if it makes sense. Note the illustrations:
http://www.cloudynig...hp?item_id=2677
You can also drop me a message on CN if you have a specific question.

#7 FirstSight

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Posted 11 June 2013 - 02:34 PM

The autocollimator is seemingly bewilderingly confusing at first, but though learning what the various multiple reflections actually are is worthwhile (and a bit complicated)...the ESSENCE of what you're trying to do is stunningly simple: tweak the secondary adjustment screws until ALL the other center-spot reflections merge and disappear behind the brightest one (which is the direct single-pass image of the center spot rather than a multiple-pass reflection of the center spot like the fainter ones are). Once you succeed at this, you're not quite done: recheck your primary's alignment with your cheshire. If (as is more likely) tweaking the secondary to satisfy the autocollimator has nudged the primary alignment off a bit, adjust the primary back into alignment using the cheshire and then repeat tweaking the secondary with the autocollimator. Two or three iterations back and forth will, most of the time, be sufficient to get cheshire and autocollimator to agree.

BTW: don't overly obsess at first on trying to make all the fainter reflections *perfectly* disappear, as opposed to being content with a tiny sliver of one peeking out from the main reflection; you'll find that even a slight tweaking of the thumbscrew adjusting how tight the autocollimator is held in the focuser will quite noticeably change how the reflections stack (or don't). Your ultimate goal is to try to make 'em entirely disappear, but don't let the absolutely perfect be the enemy of the very good here.

YES, there is an alternative method called the "carefully decollimated primary" procedure which short-cuts this iterative process, but while this alternative procedure (invented an popularized by collimation guru Vic Menard) is definitely worth *eventually* learning, LEARN THE ITERATIVE PROCESS FIRST, because the goals of the two key iterative steps are so straightforwardly simple that you're less likely to get confused.

In short, focus FIRST on what simple thing you need to accomplish with each of the two key iterative steps, and THEN that successfully accomplished, it will become much easier to understand *what* each step is actually doing, and then subsequently, to learn the alternative "carefully decollimated primary" procedure.

#8 UmaDog

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Posted 11 June 2013 - 10:01 PM

I second the iterative method. It works very well and is simple to learn. In fact, I find it sufficiently convenient that I've not bothered with the CDP method.

#9 rlmxracer

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Posted 11 June 2013 - 10:48 PM

I second the iterative method. It works very well and is simple to learn. In fact, I find it sufficiently convenient that I've not bothered with the CDP method.

X2, my issue w/ the CDP is two fold. 1.My mirror needs a recoat and the area around the center spot has a small bit of residue that I can't get off. That makes it hard for me to precisely stack the images.
2. I also find it difficult to figure out which primary adjustment screw to turn because I can't look through the center pupil and adjust the screw at the same time. When I use my cheshire to adjust the primary it is more obvious because I'm only dealing with one reflection.

#10 Jason D

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Posted 11 June 2013 - 11:04 PM

my issue w/ the CDP is two fold... I also find it difficult to figure out which primary adjustment screw


CDP is meant for the secondary mirror. You are not suppose to adjust the primary mirror to stack reflections P&3 but rather only the secondary mirror set screws. See attachment.

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#11 rlmxracer

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Posted 11 June 2013 - 11:12 PM

my issue w/ the CDP is two fold... I also find it difficult to figure out which primary adjustment screw


CDP is meant for the secondary mirror. You are not suppose to adjust the primary mirror to stack reflections P&3 but rather only the secondary mirror set screws. See attachment.

Sorry I wasn't clear my bad. It is after this step when you recolimate the primary I have a dificult time. Thanks Jason.

#12 Jason D

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Posted 11 June 2013 - 11:38 PM

If you have the triangle or the Hotspot center spot then it makes it easier to figure out which knob to use providing each corner of the triangle/Hotspot is pointing towards a primary adjustment screw.

Jason

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#13 rlmxracer

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Posted 12 June 2013 - 12:02 AM

If you have the triangle or the Hotspot center spot then it makes it easier to figure out which knob to use providing each corner of the triangle/Hotspot is pointing towards a primary adjustment screw.
Jason

I have a Hotspot and as with the above pic it is easy for me with the cheshire (single reflection). It is just the final stacking of mulitple images I cant seem to get the stacked perfectly. In part it's due to the small bit of haze around my center spot and the fact that I can't watch the reflections as I'm recollimating the primary (arms arent long enough lol).

#14 Jason D

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Posted 12 June 2013 - 01:52 AM

With the XLK, you iterate between the stacking of P+2 from the offset pupil and the Blackcat cheshire -- in case you select not to use CDP. Checking the stacking of P+1 from the central pupil is only meant for final confirmation.

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#15 hungerford

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Posted 13 June 2013 - 08:45 AM

Thank you very much for your help.
I think I must learn to identify all the reflection properly and then use it.
Vince

#16 dscarpa

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Posted 13 June 2013 - 09:51 AM

I understand just a little. No comprende it's a riddle. David

#17 Sarkikos

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Posted 13 June 2013 - 10:45 AM

...the ESSENCE of what you're trying to do is stunningly simple: tweak the secondary adjustment screws until ALL the other center-spot reflections merge and disappear behind the brightest one (which is the direct single-pass image of the center spot rather than a multiple-pass reflection of the center spot like the fainter ones are). Once you succeed at this, you're not quite done: recheck your primary's alignment with your cheshire. If (as is more likely) tweaking the secondary to satisfy the autocollimator has nudged the primary alignment off a bit, adjust the primary back into alignment using the cheshire and then repeat tweaking the secondary with the autocollimator. Two or three iterations back and forth will, most of the time, be sufficient to get cheshire and autocollimator to agree.


This is exactly how I collimate my Newts. The result is very close collimation, especially advantageous for planet/lunar observation, but I also notice improvement in sharpness and contrast for DSO.

Mike

#18 hungerford

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Posted 03 July 2013 - 03:16 AM

Hi,
I now understand the Cateye collimator unfortunately the secondary holder is giving me some problems.
Basically it is of poor quality and when I try to adjust it, it jumps and I cannot get a good collimation of the secondary.
Any idea what can be done to remedy this problem.
The scope is a GSO 10".
Thank you for your help.
Vince

#19 panhard

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Posted 03 July 2013 - 06:30 AM

Cut out the side of a plastic milk container, to make 2 washers. Insert them next to the secondary holder. That way the small screws act on the washers not the rear of the secondary holder. You will need a hole for the centre screw to go through. Then reassemble everything, do this with the tube horizontal so nothing hits the primary mirror. It sounds like you have put dents in the rear of the secondary holder. :cool:

#20 maakhand

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Posted 03 July 2013 - 10:09 AM

I have a Hotspot and as with the above pic it is easy for me with the cheshire (single reflection). It is just the final stacking of mulitple images I cant seem to get the stacked perfectly. In part it's due to the small bit of haze around my center spot and the fact that I can't watch the reflections as I'm recollimating the primary (arms arent long enough lol).


the trick i use to collimate my Z10 is that i sit on my denvar chair, look through autocollimator/cheshire, swing the focuser end of tube from me so the primary end of tube reaches my extended right hand, half a turn on a screw, pushing bottom end away so focuser end reaches my left hand, peek through focuser and so on :)

#21 RAKing

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Posted 03 July 2013 - 01:47 PM

the trick i use to collimate my Z10 is that i sit on my denvar chair, look through autocollimator/cheshire, swing the focuser end of tube from me so the primary end of tube reaches my extended right hand, half a turn on a screw, pushing bottom end away so focuser end reaches my left hand, peek through focuser and so on :)


I think Richard Simmons did an exercise video on that same technique. It's called "Sweatin' the Collimation". :lol:

Cheers,

Ron

edit: corrected Richard's spelling. :)

#22 hungerford

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Posted 04 July 2013 - 01:44 AM

Since Richard Simmonds is not known here I have spend 30 minutes trying to locate the video. My wife took a look at your email and burst into laughter and told me it was a joke as Richards Simmonds is a exercise instructor.
Good one I should have realised it was a joke but I was slow this morning. :)
Vince

#23 Jason D

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Posted 04 July 2013 - 02:02 AM

Since Richard Simmonds is not known here

I thought it is common knowledge about who Richard Simmons is -- at least for those who are middle aged living in the USA.
By the way, it is "Simmons" -- not Simmonds.


Back to collimating with the autocollimator, I do not "swing" my XT10 OTA. I extend my body and arm to reach the primary knobs while sitting down. What makes it easy for me is that I know exactly which knob to touch and approximately by how much I should turn it.
Jason

#24 maakhand

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Posted 05 July 2013 - 04:31 PM

The OP I was replying to has the zhumell 10" as me and we both can't really adjust primary collimation screws while looking through focuser. He was wishing for longer arms. I am sure it is because zhumell fl is 1250 mm compared to xt10's 1200mm. Hence my swinging trick ;)

#25 Jason D

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Posted 05 July 2013 - 04:52 PM

we both can't really adjust primary collimation screws while looking through focuser

You do not have to. If you mentally marked which Hotspot/Triangle tip corresponds to which primary knobs then you can make the adjustment quick then reevaluate.

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