Orpington Astronomical Society

Astronomy => Technical => Topic started by: Tony G on Jan 24, 2010, 17:13:28

Title: Collimator
Post by: Tony G on Jan 24, 2010, 17:13:28
Hi all,

Can anyone recommend a laser collimator which I can use on a Newtonian, which doesn't need to much collimating itself, every time I want to use it. ;)

Tony G
Title: Re: Collimator
Post by: mickw on Jan 24, 2010, 17:30:43
I would reckon that any collimator would be OK because once "IT" is collimated with screws it would stay sorted - until you backed the car over it  :o
But something on the lines of this should take a lot of the pain out of it as it doesn't clamp the collimator on just one side.

self centering adapter  (http://www.telescopehouse.com/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2etelescopehouse%2ecom%2fcgi%2dbin%2fss000001%2epl%3fRANDOM%3dNETQUOTEVAR%253ARANDOM%26PAGE%3dSEARCH%26SS%3d57072%26TB%3dA%26PR%3d%2d1%26ACTION%3dSearch%26GB%3dA&WD=centering&PN=Orion_Precision_Eyepiece_Centering_Adaptor__2513%2ehtml%23a1_2152072#a1_2152072)

I have one if you like to try it out
Title: Re: Collimator
Post by: Tony G on Jan 24, 2010, 18:24:14
Mick,

Looking at this, I can see that the adapter centres the eyepiece/equipment within itself, but wouldn't the thumbscrews push this adapter off centre when you tightened them? or does it work differently? :-?

Tony G
Title: Re: Collimator
Post by: mickw on Jan 24, 2010, 18:42:23
Never thought of that  :oops:
I can see no way round this - pretty stupid that focusers don't come with a similar fitting  :-?
Title: Re: Collimator
Post by: Fay on Jan 24, 2010, 19:27:44
Robert told me to position the eyepiece on top of the scope, so any collimator should sit looking straight down
Title: Re: Collimator
Post by: The Thing on Jan 24, 2010, 19:33:32
You could put some tape pieces evenly around the collimator so it sits tight in the EP holder.
Title: Re: Collimator
Post by: Tony G on Jan 24, 2010, 21:05:15
Duncan,
That's what I would have done.
Mick,
If you bought that item, are you sure you don't want to buy those attachments for £30, and sell them for £22  :D.
But I take it they are all a much of a muchness, and so price range £30 - £45 is acceptable.

Tony G
Title: Re: Collimator
Post by: mickw on Jan 25, 2010, 08:23:24
Quoteprice range £30 - £45 is acceptable

Bit much for a piece of tape though  :-?
Title: Re: Collimator
Post by: Mac on Jan 25, 2010, 12:54:03
QuoteYou could put some tape pieces evenly around the collimator so it sits tight in the EP holder.

I found aluminium cooking foil instead of tape to be better,
as its thinner, you can get a better fit.

Mind it didnt help mine, didn't realise at the time they didnt work for sct's :roll:

Mac
Title: Re: Collimator
Post by: Tony G on Jan 25, 2010, 14:15:17
Quote from: mickw on Jan 25, 2010, 08:23:24
Quoteprice range £30 - £45 is acceptable

Bit much for a piece of tape though  :-?

Bit much coming from someone who bought one of these
Quote from: mickw on Jan 24, 2010, 17:30:43
self centering adapter  (http://www.telescopehouse.com/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2etelescopehouse%2ecom%2fcgi%2dbin%2fss000001%2epl%3fRANDOM%3dNETQUOTEVAR%253ARANDOM%26PAGE%3dSEARCH%26SS%3d57072%26TB%3dA%26PR%3d%2d1%26ACTION%3dSearch%26GB%3dA&WD=centering&PN=Orion_Precision_Eyepiece_Centering_Adaptor__2513%2ehtml%23a1_2152072#a1_2152072)
and thought it would centre the collimater! :-? :D

Tony G
Title: Re: Collimator
Post by: mickw on Jan 25, 2010, 14:41:58
 :P
Title: Re: Collimator
Post by: MarkS on Jan 25, 2010, 15:00:00
Quote from: Mac
I found aluminium cooking foil instead of tape to be better,
as its thinner, you can get a better fit.

It's about 1/40mm thick (or, in old money, 1/1000 inch) - very useful as shims for adjusting the alignment of optical bits and pieces.

Mark
Title: Re: Collimator
Post by: Ian on Jan 25, 2010, 15:29:48
would that be Tesco's value foil, the Tesco's standard brown boxed foil or the extra strong turkey foil? How about the quilted variety?

(I've discovered that you don't really need extra strong foil provided you ensure the turkey is dead before placing it in the oven)
Title: Re: Collimator
Post by: Rocket Pooch on Jan 25, 2010, 20:36:36
Hi,

A collimator only gets it about 90% of the way there then star collimation should do the rest.  My meade one has been ok, but I still tweak it a bit.  Hence bobbs thingies.


Chris