collimating Newt without laser

[Somnium (Aidan)]

i don't really trust my laser collimator tool for a few reasons,
1) i am not sure how the image is affected by weight changes when i ad barlows etc
2) my laser collimator may be slightly out of collimation
3) i am trying to be as perfect as possible for get great planetary images

my thought was that i could load up my imaging train and then point to an object like Saturn or the moon, go out of focus a bit and manipulate the primary mirror until the shadow of the secondary is directly in the middle of the disk of light. would this work or am i missing something that is making me sound stupid?

[astroboof (Steve McN)]

Well, maybe give it a go, then get your kit off and test it out by the standard methods you already have, and even a humble film canister tool as well, it's a poor mans cheshire. That'd possibly indicate a number of things. But really, the collimation via that style would be vague at best was my recollection of trying such things yonks ago on a 10" f5 newt, as there was some flexure in the 2" crayford draw tube, a feathertouch it wasn't.

[rmuhlack (Richard)]

Originally Posted by Somnium

3) i am trying to be as perfect as possible for get great planetary images

in that case your proposed method will not be suitable. I suggest you look at Catseye collimation tools http://www.catseyecollimation.com/

I have the Triplepack XLSKP with the optional clip light and case, which i am very happy with. Have used it now on three separate newtonians (at f4, f5 and f6) and once you've mastered the collimation procedure it delivers perfect collimation in a matter of minutes.

[Somnium (Aidan)]

thanks for that Richard and Steve, i guess my only concern is the play in my GSO focuser. i have really struggled to get great planetary images and i think it is due to collimation issues. no matter what i do i just cant seem to get it perfect

[AlexN]

I've been using a cheap gso lazer in Richards old 5" f/5 and my 8"f/5 and have found results to be really quite good however this is for prime focus deep sky imaging. Once you add a 5x powermate for planetary work the requirement for perfect collimation is far greater.

[5ash (Philip)]

Everyone so far seems to have assumed the secondary mirror is collimated properly. A laser collimator will still appear to collimate the primary even if the secondary is out of collimation with obvious results . Perhaps we should concentrate on getting the secondary collimation OK before using the laser collimator to collimated the primary, that's assuming the laser collimator is OK.
Philip

[multiweb (Marc)]

Originally Posted by Somnium

i don't really trust my laser collimator tool for a few reasons,
1) i am not sure how the image is affected by weight changes when i ad barlows etc
2) my laser collimator may be slightly out of collimation
3) i am trying to be as perfect as possible for get great planetary images

my thought was that i could load up my imaging train and then point to an object like Saturn or the moon, go out of focus a bit and manipulate the primary mirror until the shadow of the secondary is directly in the middle of the disk of light. would this work or am i missing something that is making me sound stupid?

Catseye collimation kit. Do it and never look back.

[Somnium (Aidan)]

thanks guys, i might invest in a catseye collimator. has anyone had experience with the GSO crayford 10:1 and noticed any issues with flexure when loading up barlows and cameras?

[AlexN]

My gso focuser handles an mpcc, ao7 and sbig st2000xcm.. All up around 2.6kg without dramas.

[Somnium (Aidan)]

Originally Posted by AlexN

My gso focuser handles an mpcc, ao7 and sbig st2000xcm.. All up around 2.6kg without dramas.

thanks Alex.