Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

blinky

Is this my primary or secondary out of collimation?

Recommended Posts

Im using live capture on an out of focus star - I can see the big circle (I assume the primary) is presenting a circle, but the smaller shadow (assume the secondary) is not - does this indicate the secondary is not collimated?

 

 

OutofFocusStar.JPG

Share this post


Link to post
Share on other sites

If the telescope is of reasonable size and relatively fast focal ratio the displaced shadow might well be showing the offset of the secondary mirror.         🙂 

  • Like 1

Share this post


Link to post
Share on other sites

That has just dawned on me in the last 5 mins after packing it all up and coming inside!  I think I made it slightly better and the stars look round etc - how can you tell if a newt is in perfect collimation if the secondary is offset?  I assume mine is since its an F4 scope.....  I originally used one of those co-centre devices and tonight made tweaks to the primary and secondary - Im now worried that I should have left it alone after collimating the secondary with the cocentre and the primary with the laser and Ive made it worse - but Im telling myself the stars were round and the out of focus star looks better now than it did and to leave it be and not let the laser near it till it needs recollimated!  Does that sound good?

Share this post


Link to post
Share on other sites

I always struggled with getting the secondary exactly centred and appearing as a perfect circle, that's why I bought the concentre device Craig.  I always struggled with a Cheshire on the secondary, and found a laser to be worse than useless.

Treat yourself to a concentre for xmas 😃

Concentre for the secondary, decent cheshire for the primary and then star test.

Share this post


Link to post
Share on other sites

To be honest I could not get it completely centred in the co centre either!  although I did sort the rotation and make the secondary round.  Really need a clear night to star test now, clouded over immediately after I collimated!

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.