Collimation enquiry

[rustigsmed (Russell)]

Hi I'm looking at upgrading my collimation 'quality'.
I currently have been using naked eye and a glatter barlowed laser.

I've been eyeing off the catseye 2" kits that have a cheshire and the infinity XL or infinity XLK autocollimator ($156 & $185).

has anybody had much experience with these or can they give any advice?

whilst i've been getting ok results with my existing method, i want really get it spot on, fuss free for astrophotography with a coma corrector.

Thanks

Rusty

[ausastronomer (John Bambury)]

Hi Russell,

You haven't told us what telescope (s) you have but let's assume you have a medium aperture (8" to 16") newtonian.

Unless you are very experienced in all of the mechanics of collimation you need a tool which will help you to align and correctly position the secondary mirror, in addition to your barlowed laser, which does a good job on the primary mirror.

The Catseye system is the Rolls Royce and highly recommended. If you are going to spend that much money go the whole hog, spend the extra $29 and get the autocollimator as well. These tools will do the entire collimation process, including your primary. You still keep your barlowed laser and use it for quick checks on the primary whilst in the field at night.

A cheaper option which works extremely well also is the Orion Collimating eyepiece which is a combination Cheshire / Sight tube

http://www.bintel.com.au/Accessories...oductview.aspx

These are only $59 and do a very good job of the entire collimation process, including both the primary and secondary mirrors. Again, you still keep your barlowed laser and use it for quick checks on the primary whilst in the field at night.

To be honest I find the Orion tool to be very good value for $59 and an excellent tool for all levels of user. It is a much better quality tool that some of the combination cheshire / sight tubes which have been produced over the past 10 years. The tolerances on the Orion Tool are pretty good.

I have the Tectron Tools which are a very early version of and quite similar to the Catseye System, made by Tom Clark, plus the 2" Astrosystems barlowed laser, but to be honest I could collimate any of my scopes just about as well, with the Orion Collimating Tool, which I have used on many occasions.

Cheers,
John B

[alistairsam]

Hi,
I'd second that.
I use the Orion Collimating Eyepiece and a Cats Eye infinity XLK autocollimator.
The XLK is really good and well worth it.
my scopes are F4's.
I would recommend a 2" sight tube as well. That helps with centering the secondary which is very important.
Or you could centre/offset spot the secondary with a felt marker, and center it with the collimating eyepiece.

[rustigsmed (Russell)]

Thanks for the advice Alistair and John,

Yes, sorry an f/5 12" dob (SW truss), but i'm also probably getting at an f/4 or f/5 8" for imaging.

Righto, so the Orion tube is also good but only comes in the 1.25" (i think). whereas the catseye package (i forgot to mention) has the 2" tube. So as long as the 8" newt i buy has a 2" focuser I should be alright.

John i think the extra $29 differentiates between two types of autocollimators that catseye offer (in addition to the cheshire).

it looks like you can choose options on what image it projects eg 'red triangle 3/16" or 'red triangle 1/4" 'does the size make much difference?

Thanks again

[Jason D (Jason)]

Originally Posted by rustigsmed

it looks like you can choose options on what image it projects eg 'red triangle 3/16" or 'red triangle 1/4" 'does the size make much difference?

The 3/16" and the 1/4" is the size of the inner hole of the center spot. The hole size does not matter when using the Catseye tools. That is, none of the tools will make use of the inner hole. In fact, I believe Catseye even offer a solid center spot without holes.

The hole size if important when you use non-Catseye tools such as laser collimators and the cheshire/sight-tube combo tool. For laser collimators, the size of the hole matters when using barlowed laser -- a larger hole might more desired. For cheshire/sight-tube a smaller hole is more desired.

If you decide to purchase the Catseye kit, I would recommend getting the Hotspot center spot. It comes in one center hole size. See attachments.

Jason

[simmo]

hello rustigsmed,

You might want to check out astrosystems for their other collimation stuff as well.

"Special, get both the 2" LightPipe/SightTube and 2" Autocollimator for $165"


I just got their 1.25" set sent and it cost $80 + postage which was $16 to Perth ($US too). The instructions are pretty clear but a little in depth but as far as I can tell it will be worth it though. I used just the autocollimator the other night and it seemed to give my scope a better picture. I have to find some time to do the rest. By the way I'm using a SW dob as well. Randy Cunningham at AS was very good with service and replied to my Emails the night it was sent.

Cheers Simmo

[rustigsmed (Russell)]

Thanks for the info Simmo and Jason

I'll check out astrosystems and guidance on the hotspot is exactly what i was after

thanks again!