collimating a newtonian

[davekelley]

I have a skyliner 150p f8.  I have a cheshire collimation cap and a laser collinmator.  The laser tells me I have things just about perfect. It wasn't easy to get this result!  In the cheshire collimation cap, things don't look right.  Isn't  this a frustrating hobby!

 

[Ricochet]

 Firstly, do you have a Cheshire or a collimation cap? They are different things. Whichever you have, you need to collimate the laser before you use it by putting it in a v block and rotating it to check the dot stays centred on a single point. If a Cheshire and laser don't agree then the chances are that it is the laser that is wrong. 

[Jimtheslim]

This is why I am reluctant to buy a laser. I think my collimation looks good through the Cheshire, I get great views and nice symmetrical, concentric donut rings when going in and out of focus. Now I just know if I get a laser, even if collimated, will tell me this is out and I will spend forever fiddling and stressing out

[laudropb]

Have you collimated your laser ?

[REG78]

Try putting sheet of paper to block primary mirror frm your view when using your chesire and get ur secondary mirror squared to your chesire while looking through it you should try get it so that it is a circle in th centre of view thn it should b plain sailing after tht wen u use your lazer.......hav you centre spotted your primary mirror yet this helps out a lot 

[davekelley]

2 minutes ago, laudropb said:

Have you collimated your laser ?

I don't have a v-block, (don't know what one is!  I have a cheshirte and a lase.  It is so difficult to adjust these mirrors, they don't move easily and don't go the direction you expect them to, then they spring back to  where they were when you started!  I'm rending to think the cheshire is correct and it's the laser that is wrong but it's very difficult to diagnose what needs adjusting fom the image in the cheshire.  I guess I need to collimate the laser, but why should this be necessary?  I would've thought it's a simple enough job for a factoy to produce a properly collimated lase?    I think I've  probably made things worse!  It's been cloudy for about 3 weeks and I'm fidgetting  

 

[Charic]

I prefer using a Cheshire combination tool,  only using the  laser with a Barlow for checking  when away from the house?

Here is the guide many folk adhere to! http://www.astro-baby.com/collimation/astro babys collimation guide.htm

[laudropb]

Set up your Collimation with the Cheshire and when we get a clear night do a star test to see if it is right. Unfortunately most lasers need collimated when first purchased. You will find the method for this on You tube.

[Charic]

The Star test is the ultimate test.

Over study the collimating guide, try to think it through,  to fully understand the procedure. Once mastered, its a few minutes to complete the task?

[REG78]

I was th same Dave I got th lazer b4 I got a chesire and just knew tht it wasn't properly collimated it was my secondary tht was well off but bita tinkering with th central bolt with chesire in sortd th secondary and it's been spot on since hth  

[davekelley]

8 minutes ago, Charic said:

 

Thanks for this. These things are so difficult!

 

[barrie greenwood]

Yep I'm also new to it and it has driven me mad.

But I used a combination of the two and adjusted the secondary mirror first and then the primary and I followed some good advice and only used two of the adjusting screws and now it Looks on the money

I set up the sec mirror with the Cheshire and then the laser and back to the Cheshire this took time but eventually it got to the point of both being central then I adjusted the primary this was faster to do

Now it's done the difference is really noticeable

Baz

[happy-kat]

Did you verify your laser accuracy first?

[barrie greenwood]

Yeah I did on v blocks

[freewheeler]

My collimator definitely needed adjusting. I made a suitable cradle from a couple of straps, bent accurately to 45 degrees in the vice and a couple of 90 degree angle brackets. I used Araldite Rapid for the most part so that there were no protruding screw heads in the cradle part.

[Starwiz]

Nice work!  

John

[N3ptune]

I use the collimation cap only, so far I have great results with that tool only.  I use the Chechire to verify the job but it's always good, so now I don't even use the Cheshire.

Home made, good old cap! (I dropped it on the floor before the second picture, it's still strong has steel!)

The cap has no game when it's in the focuser, the cheshire must have something like 1/32" space around.

[Chris Murray]

Hia, research, research, research, astronomy shed video,s are great Dion will talk you through it all and tell you what not to do as well, i still fight with my quattro from time to time, good luck and be patient, chris