Collimation OCD Part Two

[TopHouse]

Following on from my previous ramblings. Finally the self centering eyepiece adapter arrived. :-

Orion Precision Eyepiece Centering Adaptor

Before I go on, after having played about with this adapter i will say it is by far the best 29 quid I have spent on my scope so far! No one can fail to agree that the 'push it in and tighten 2 screws' method is, well, a bit carp! This adapter goes into your 2" and provides a self centering, quick change, secure 1.25" So, if you haven't got a compression eyepiece fitting and are still using the 2 screws, this is the baby!

OK, so this thing is self centering, it also allows a very fine adjustment of 'grab pressure' meaning that you can insert your laser collimater (oh he's off with the collimating again!) tighten to just the 'nth' degree, allowing the collimater to be rotated, but still held tight enough to be kept square, the reason being, you can now check the collimation of your collimater, by looking down the tube to your secondary whilst rotating the collimater, if the red dot stays dead still, the collimater is 'in', if instead it makes a small circle (or even a big one) it's 'out'.

Mine was out! I have the antares one which has adjusters for collimating it, through a lot of trial and error I finally got my collimater collimated! This was in no way evident before, using the 'two screws' eyepiece holder, even pushing the collimater in and keeping the shoulder up against the eyepiece holder surface, theoretically keeping it square.

So, I collimated my collimater, then, re-collimated my scope, I'm now a happy bunny, because yes, even though i had collimated it previously, after adding the self centering adapter and collimating the collimater, it was indeed out.

The thing is, my laser collimater also allowed me to test the accuracy of the self centering adapter, by removing and re-fitting the collimater several times, it was obvious the 'dot' was hitting the same spot every time.

CONCLUSION

For 29 quid I whole heartedly recommend the Orion Precision Self Centering Adapter (I've also seen one by Antares that looks the same) it's the perfect add on for a laser collimater and it's a brilliant upgrade to the standard eyepiece holder for many reasons. I now think i've cured my collimater OCD

However, if anyone's got a cheshire hanging about doing nothing I would like to try one just to compare the results

[John]

That sounds a useful device and more accurate than 1 or 2 screws as you say. How do you make sure that the adaptor itself is centrered ? - or does it do that itself ?

[TopHouse]

Well, 'technically' it doesn't need to be centered, like on my 200p focusser, i have the 2" mount fitted, the device it then fitted to that , now unless you go onto 2" eyepieces, it never gets moved or removed, so there is no 'variance' absolute center is not the absolute issue, it's the fact that using 2 or 1 screw to fix something, theoretically each time you move those screws, ie fitting a different eyepiece, the next eyepiece will be in a slightly different place than the last, using this, the collimater or any eyepice following it are now centered in the same spot. AND, it's a lot easier on the fingers, especially in the cold.

[John]

Thanks for that - very interesting. Given you have now found M31 (ref your post on that - well done !) you may well develop an interest in 2" eyepieces - just a prediction there

[TopHouse]

OH FFS don't trigger another OCD in me LOL

I was out for a few hours tonight with the scope and I can now verify my theory, I do believe that you will NEVER get a perfect collimation just with tools and that a star collimation is the final tweak, what i can say though is that tonight I got a good star and 'knocked it out' and got the doughnut, to make it perfect it took a very very slight turn of one bolt on the secondary, and i emphases it really was slight.

Also after using it, just as an ease of use tool alone I totally recommend the self centerer, best price I found on it was £29 at scsastro. I'm one of those people who won't recommend an item if it's less than perfect, this i am over the moon with!

[Orion]

Just to confirm TopHouses opinion on the Orion Eyepiece Centering Adaptor, I got one a few months back and I can't imagine going back to the screw tightening malarky (ever) . One of the best astro buys I've ever made (if not the best - considering the low cost) .

P.S. Never have to read the "..... eyepiece is not centred... collimation wont be true... blah blah..." arguments/discussions again .

[albedo0.39]

I'd like to agree with the theme of this post. The self centering adaptor [sCA] is well worth the asking price.

However, I did some pretty accurate measurements on my scope and found that when inserting into the 2" aperture and tightening the screw locking screw, it was taking the centre of the SCA out of the mechanical centre (as was presupposed by John) - so I shimmed out the focuser so that no matter if I do remove the SCA (for 2" EP's) then when I re-insert, it takes up the correct position.

Of course, once this is done, the task of ensuring alignment with 1.25" EP's is virtually guaranteed.

Recommended.