Another Collimation question

[Neil H]

Hi everyone I hope your all well , I have a Collimation question , I am fairly good at Collimation but 3 telescopes into this hobby I have only once had a star test give the right feed back and got the concentric circles and that was the SW 150/750 The new Telescope Orion Optics VX8L 200/1200 gives me a sharp image but the star test does not come right what I get is a large circle with the spider in the middle and what looks like skinny worms in the circle any ideas  ?, I would love to get this right if what I have now is wrong ?

[alacant]

45 minutes ago, Neil H said:

gives me a sharp image

Hi

That sounds good.  According to the collimation myths, I don't think a star test is the correct way to judge collimation. You have loadsa collimation leeway on your new telescope; get it right with a Cheshire sight tube -preferably one with cross hairs to do the secondary as well- and you're good.

Just my €0.02 but hope it saves you some clear sky time:)

Cheers

[Neil H]

Thanks for that I do have a Cheshire with cross hairs , and I am going to make a Collimation cap and see how that looks in the secondary

[John]

Star testing can provide some helpful information but for it to be really useful I think it needs to be done under good seeing conditions, with the scope fully cooled, at high magnifications, and with knowledge of how to interpret the results.

This seems a helpful piece:

https://popastro.com/documents/PA_jan-mar2009_p12-13_telescopetopics_startesting.pdf

 

 

 

 

[Neil H]

Thanks I will download and read it 

[Ciaran Meier]

Hi Neil

I have an Orion Optics 8 inch newt. I had the main mirror out recently for a clean so needed collimation after.  I just collimate by visually lining up the mirriors using an old 35mm film canister with a small hole punched through the centre. Results seem good on close doubles and there's a nice uniform airy disc.  

[Neil H]

What size hole did you make in the cap

[Ciaran Meier]

2 mm approx. 

 

[Neil H]

Ok thanks I am off to Collimation street lol 

[Neil H]

On 31/03/2020 at 12:10, John said:

Star testing can provide some helpful information but for it to be really useful I think it needs to be done under good seeing conditions, with the scope fully cooled, at high magnifications, and with knowledge of how to interpret the results.

This seems a helpful piece:

https://popastro.com/documents/PA_jan-mar2009_p12-13_telescopetopics_startesting.pdf

 

 

 

 

Update.......Hi John that link you posted was really good , I did star test tonight and it was spot on ,so very happy I got the Collimation right 

Edited April 3, 2020 by Neil H