Cannot get collimation right

[poogle]

I've been trying to get the collimation right on my 150p newtonian for a couple of days, but so far I'm not getting it right.

See attached image for a view of a defocused star with a very odd shape. Notice the strange pattern top-left. Today it struck me: might this be a case of over-tightened primary mirror clip retainers?

/Patrik

[poogle]

Sorry, wrong image above

[hippie]

Try this link Patrik :- http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

This will help your collimation  for your scope, You may have to try a few times before getting it right, .

[astronymonkey]

Hi poogle, that image suggests that there is something in the way of the light path as the image is no where near round. Is anything obscuring the tube or mirrors like loose flocking etc ?

Cheers

[moriniboy]

Hi poogle, that image suggests that there is something in the way of the light path as the image is no where near round. Is anything obscuring the tube or mirrors like loose flocking etc ?

Cheers

My thoughts exactly, had the same when a shroud came loose on a flextube and moved in front of part of the primary

[ronl]

Have you tried loosening them then rechecking, but it looks like the secondary mirror

is out of alignment, follow Astro Baby's guide and you won't go far wrong, do you use

a collimation cap and Cheshire, or do you use a laser collimator, do a star test after

collimating.

[itmo]

best to use a cheshire for rough alignment. seems to me that the secondary is off and the primary is also a bit off. also might be a bagging shroud or something. 

[jetstream]

It might be useful to start from scratch,using the cheshire/sight tube combo.Secondary first,then the primary.The mirror clips should not hold the mirror tight or allow it to bind.Keep on trying and asking questions,members will help you get it right.

[poogle]

Thanks for all the tips!

I have now checked the primary mirror clips and they were really tight, so I loosened them a bit. Will have to wait for a starry night and see if that helps. If not I will start from scratch. I don't have a cheshire, but use a collimation cap and a collimated laser. I have also tried a webcam instead of a collimation cap, but I find it difficult to center it in the focuser. 

I recently fitted a Moonlite focuser and tried to fit it square, but is that really important for the collimation? There are just so many parameters to consider

[RichM63]

Yes, if you think about it, if the focuser is pointing down into the tube squewed, then the reflected light wont be square on going up it.

Now that you have randomly loosened the primary, you will have to collimate procedurally.

But DON'T PANIC my 200P was so hacked about when I bought it S/H that the guy told me it didn't work.

I followed the advice on here, + Tube videos and came to a method that works.

This thread is great.  http://stargazerslounge.com/topic/206455-someone-else-with-collimation-woes-with-photos/

[Peter Drew]

It might be worth loosening the mirror clips a "bit more", they should barely touch the mirror, in fact you should be able to slide a piece of thin paper between the clips and the mirror. It takes surprisingly little pressure to distort a mirror optically.    

[todd8137]

Looks like the secondary is way off

Pat

[Andy 5312]

Whilst on the subject of collimation, why doesn't the Skywatcher 130 have a centre spot on the primary ? . I know my scope is slightly out, but the thought of collimating without a centre spot is daunting. I dont really fancy the option of taking the primary out and attempting to add my own centre spot.... i would much rather have to face the rage of an angry rhino about to charge , and my only line of defence being a feather duster.........( sorry....im a drama queen) Why not put a centre spot......?

[poogle]

After loosening the primary mirror clips I get no distortions like the one in the image attached earlier! Now i just need to collimate it, but that should be no problem now *fingers crossed*

I made myself an artificial star with a bright LED and some fibre optic cable so that I can collimate whenever I want

Again, thanks for all the helpful advice.

/Patrik