Just to keep it fair.
Lets not get into a brand name war please.
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Hello Richard,
We have been making collimation tools including the Laser, lightpipe/sightube and autocollimator for over 20 years. It is unfortunate that there is a lot of conflicting information out there about their use. Our Autocollimator is adjusted with an optical set-up having a 100' path. All others are just assembled mechanically and machine tolerances determine the accuracy. We adjust the tilt of the cap which holds the mirror to align the autocollimator, therefore the cap is not perpendicular to the body, so when the autocollimator is placed in the drawtube it is not inserted with the expectation the cap will be flush with the drawtube. Persons trying to force the cap flush with the drawtube has been one source of calling our tools "inaccurate". The three items in Jasons note are all incorrect in some way. First it is not necessary to see the fourth reflection, although you usually can. This level of collimation accuracy exceeds the ability of a telescopes structure to hold accurately. You will notice everyone talking about tool accuracy with no mention of the telescopes ability to hold it. What most assume or don't want to admit is that most production telescopes won't hold the single pass accuracy achieved by a laser or Cheshire (lightPipe). If you can percieve any movement of the laser spot within the center spot of the primary (1/2 pass) or on the bottom of the tool at the focuser (1 pass) when moving the telescope up and down then there is little need to waste time on using an autocollimator.
Item 2, flatness of the mirror is not critical, it is the center of the reflected spot that is being lined up so slight deviations in the appearance of the image have no affect.
Item 3 He is confusing the test for a laser which can be evaluated by rotating in the focuser. Doing this with an autocollimator cannot be done without tipping the autocollimator and seeing some movement since it only takes 1-2 thousandths of clearance between the two to show it.
I wrote the instructions and stand by them, they have been evaluated for over 20 years by thousands of customers. There seem to efforts by some manufacturers to keep collimation difficult and muddy the information water to get customers to buy their tools out of frustration.
As far as our tools accuracy, it is interesting that we have never gotten a autocollimator returned that did not test accurate. Our experience is that many have some difficulty learing the tool or don't care to take the extra time needed and rather than admit this go to the fallback "innacurate tool" defense.
We stand behind our product with a money back guarantee and complete customer support.
Randy Cunningham
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Hi Richard,
Adding the thread is fine. I'm just trying to figure a way to dispel a lot of misconceptions that sadly, seem to be coming from manufacturers as a ploy to sell their products. I'm not saying it is across the board and some is obviously unintentional. There is one other option I haven't mentioned, that is using a laser or a Cheshire (Lightpipe) to get basic collimation and then use the star test for fine collimation. It is as accurate as an autocollimator and costs nothing and can be done at night, unlike the autocollimator. You have no doubt noticed that all the finer collimation methods are not intuitive like the Laser or Cheshire and have a learning curve.
Randy Cunningham
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As for my decision:
As others have said, the Catseye tools (thanks Erick for the trial run) are very impressive tools, quality and accuracy.
The ac is to fiddly for me, and as Randy points out many scopes including mine will not be able to hold this very accurate fine tuning as I noticed during the trial run, so it's not worth all the fuss. Brilliant for quality scops.
I'v decided to get myself a good 2" barlow laser. I think I was told to do just that by Mr.47TUC back at the Snake valley camp earlier this year, why don't I listen?
Thanks one and all.
Richard
) divided by 8 passes = laser scribing a circle on the primary of a 1.25mm radius. Is that right?
In my experience a tilted mirror is a problem. I have experienced this on an A/C with an SCT. Very hard to iterate towards a finer alignment if your A/C mirror is not square. Unless I'm missing something?
