Sign in to follow this  
Followers 0
wisewoman

Collimating a SW 200p

22 posts in this topic

Hey ho,

I managed to get some scope time a bit earlier this evening before the clouds came in. I thought I'd check collimation by defocussing on a star and it does seem slightly out. I've been looking at how to collimate scopes on the web and it's making my head hurt!

Having only had refractors previously this is a whole new area for me so can someone recommend an easy method/website and/or a device that would enable me to get good collimation on the SW 200p. Can i get away with a film canister lid with hole in it or should I go for a laser device? or Cheshire??

Thanks,

Melissa

Share this post


Link to post
Share on other sites

Yes, pop over to Astronomy shed,

http://www.astronomy...forum/index.php

there are excellent video tutorials on how to collimate your scope. When you have your TAL Barlow, there's a method called Barlowed laser, for which you will need a laser collimator. This is a dead easy and reasonably accurate method and I do it just about every time I use the scope, the laser will come in handy for centering the secondary as well.

Dion does a great job of making it easy to understand, but if you get stuck just ask and we will help, and if it comes to the worst we will do it and show you.

Share this post


Link to post
Share on other sites

Collimation looks daunting but once done a few times becomes very simple indeed.

I find a collimation cap which is basically a film cannister lid with a hole in it and a hotech laser collimator is the way to go.

Share this post


Link to post
Share on other sites

I see the hotech is a pricey one at nearly £100 are the cheaper ones any good? I have seen laser collimators for around £30 on Ebay - about the same price as a Cheshire and also around my sort of budget! :D

Also Doc are the 'Hidden Treasurers' in your sig the ones listed in the James O Meara book?

Melissa

Edited by wisewoman

Share this post


Link to post
Share on other sites

Hi Melissa.

I have this one from FLO......

http://www.firstlightoptics.com/collimation/baader-laser-collimator.html

Baz senior (Martyn) showed me how to collimate my 200p with a laser but I am having doubts as to how good a laser is, I found that in our standard focuser ep, the laser collimator can move, so one minute the collimator says it is fine, you take it out, put it in again and it says it is out. If you can, try before you buy, but i think I may go down the Chesire route soon, may ask nicely some more people on here including Martyn to show me again, there is also a way to barlow your laser collimator so you can check both your primary and secondary, I was shown but can't remember.

Share this post


Link to post
Share on other sites

Yes Millisa the Hidden Treasurers' in my sig come from the James O Meara book.

As for the Hotech, yes it is dear but it's extremely well made and as far as I know never goes out of collimation, if it does Hotech recollimate for free. Cheaper ones do go out of collimation or even arrive out of collimation.

My 16" truss dob needed collimation every time it was used thats why I bought the best, smaller dobs do not need that and tubed dobs should only need it every now and then.

Share this post


Link to post
Share on other sites

Daz - thats a really good point about the focussers on the 200p - I can see that they could be problematic with a laser. I also noticed that in this collimating tutorial using a 200p (f5) the writer doesn't like laser collimators: http://www.astro-bab...ion%20guide.htm

I'm leaning towards a cheshire but I think I will do a bit more research!

Melissa

Hi Melissa.

I have this one from FLO......

http://www.firstligh...collimator.html

Baz senior (Martyn) showed me how to collimate my 200p with a laser but I am having doubts as to how good a laser is, I found that in our standard focuser ep, the laser collimator can move, so one minute the collimator says it is fine, you take it out, put it in again and it says it is out. If you can, try before you buy, but i think I may go down the Chesire route soon, may ask nicely some more people on here including Martyn to show me again, there is also a way to barlow your laser collimator so you can check both your primary and secondary, I was shown but can't remember.

Edited by wisewoman

Share this post


Link to post
Share on other sites

i`ll pull up a chair on this one,

collmination, and how to do it correctly must be one of the biggest head aches to baffal us mortals, everyone does it slightly different, and like said everytime you but the laser back into the focusser it`s different, moving the scope plays havoc with the collminator as it seems to droop

Share this post


Link to post
Share on other sites

I purchased a cheshire collimator and it's easier to use than most folks say.

I was told a few times that collimation is a two person job, but if you are patient and don't mind bit of switching between the focuser and collimation screws then it's really quite easy.

Share this post


Link to post
Share on other sites

I'd go with the cheshire and a collicap / film canister to start with. Lasers are very useful if time is short.

Share this post


Link to post
Share on other sites

When ever I used a cheshire I found that the accuracy varied so much depending on where you placed your eye. To get increased accuracy move further away from the peephole.

Share this post


Link to post
Share on other sites

When ever I used a cheshire I found that the accuracy varied so much depending on where you placed your eye. To get increased accuracy move further away from the peephole.

Nice one Mick, good tip, it seems this collimation business is more tricky than I ever imagined, what with laser collimators giving differnet readings just by taking it out and puttting it back in again, to the collimation varying depending on where you put your eye using a Chesire, will this collimation nightmare never end?

Would you suggest both a laser and a chesire or is that ott, just do your best with the product you choose?

Edited by Daz type-r

Share this post


Link to post
Share on other sites

I would go with the cheshire and do as Mick says... It's all about line of sight. The further your eye is from the peephole, the less the field of view and the more accurate the collimation. :)

Share this post


Link to post
Share on other sites

The reason the laser is different everytime you try it is the slop in your focuser. The hotech solves half of this by centering the collimator but when you insert your eyepiece it still pushes it to one side. You can use an Orion self centering adapter but I think this only works with 1.25" eyepieces but does solve the problem

Share this post


Link to post
Share on other sites

Cheers Mick, I will look into that, thanks for all your advice, owe you a pint!

Share this post


Link to post
Share on other sites

Hello folks,

What is the difference between a long and a short Cheshire? (apart from size of course!) :D

I'm also assuming that not all Cheshires are made the same so which brands should I go for? Am i right in also thinking that I would need to buy or make a collimating cap or do they tend to come with Cheshire eyepieces?

Thanks

Melissa

Share this post


Link to post
Share on other sites

Hello folks,

What is the difference between a long and a short Cheshire? (apart from size of course!) :D

I'm also assuming that not all Cheshires are made the same so which brands should I go for? Am i right in also thinking that I would need to buy or make a collimating cap or do they tend to come with Cheshire eyepieces?

Thanks

Melissa

Use the long cheshire if you are having difficulty seeing all three primary mirror clips.

The collimation cap enables you to get the secondary to look as circular as possible.

The link below was the best site I found on collimation and this is how I learnt the dark art.


/>http://www.propermotion.com/jwreed/ATM/Collimate/Chesire.htm

Share this post


Link to post
Share on other sites

As an aside Mick, I may have further input on the camera collimation front we once went into in great depth. Still waiting for a couple of bits and bobs but it could get 'interesting' ;)

Share this post


Link to post
Share on other sites

That would be great Dion as I really enjoyed that and I think we had reasonable success.

Share this post


Link to post
Share on other sites

I can't see the primary clips using a cheshire so I use a colli cap for centring the secondary then cheshire for the primary. I know Doc's right with the line of sight thing but I found with practise, during the day, I could get the laser and cheshire results to agree.

Share this post


Link to post
Share on other sites

I agree John that with practise it is possible but I just wanted instant results and trying to use the cheshire in the dark annoyed me.

Share this post


Link to post
Share on other sites

Using a cheshire in the dark!!! I'd rather drink lager.

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
Sign in to follow this  
Followers 0