collimation???

[theghettostylus]

Me again! I apologise in advance for all the questions but anyway,can I do a full collimation with just a collimation cap???

I made one from my eyepiece cover and after buying a proper one notice I am very slightly off? Not bad for a first attempt though.

I don't have a lot of spare cash at the moment so I am crossing my fingers that the answer is yes...

[RichM63]

YES. Although you can make things easier if you have a point n shoot camera, some coloured card, and a little trick called Als Collimation aid.

The coloured card is placed in the tube to block the primary mirror and opposite the focus tube to work on the secondary (first).

Then an image or images are taken with the camera square in the focuser and the resulting image over laid with Als Colli' Aid to check that the circles are aligned.

Once the secondary is aligned, remove all the card etc and align the primary with your collimation cap.

Followed by a Defocused star test later at night.

[theghettostylus]

Thanks for that!!! Something to look into. I do have a point and shoot in the house, I was looking at Jupiter and the moon last night and the moon looked super crisp, what would it look like fully collimated? I may have a heart attack at the sites aha

I will look into the collimation aid now! Do a little google search!

Thanks for the swift and informative reply!

Loving this forum already!

[Jason D]

If used properly, a collimation cap should be able to provide good views at the EP. I believe you can center/round the secondary mirror under the focuser without the need for camera.

In the future, you can consider getting quality collimation tools.

Jason

[theghettostylus]

It is something I want to learn and get used to doing as like now I will need the skill, sometimes while taking the scope out of the shed I do often bang it against the door frame and I'm sure over time this could knock out the mirror. I don't have a centre dot on my mirror and don't want to mess around and put one on for noe so a laser is out of the question. The hole in my home made cap probably wasn't dead centre because when I use the homemade cap it looks perfect, but with the align collimation cab I got it is a little off. But I like to tinker and mess so its all good practise

[Jason D]

 I don't have a centre dot on my mirror and don't want to mess around and put one on for noe so a laser is out of the question. 

The collimation cap will not help in this case other than centering the secondary mirror under the focuser.

[RichM63]

Blast the visual aid didn't load.

[Dave In Vermont]

Here's one of the clearest guides for collimation. And it's written by a member here:

http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

Many people think collimation is something requiring a Phd in math. This de-mystifies the process.

Clear & Sharp Skies,

Dave

[theghettostylus]

I followed the astro baby guide but used the collimation cap rather than a Cheshire, as I don't have one. Did a quick star test and its only out by a fraction. Also I noticed the hole in the cap would never centre... The reason being my focuser draw tube is a tiny bit off to one side :0 I bet that won't help the process! I will adjust with a star test tomorrow as its giving out clear skies and see how everything looks, and here was me thinking I could buy a telescope and look at the stars and planets and that would be that... So is a centre dot a must for proper collimation? I will get a Cheshire soon as I don't trust the laser as it would be a cheap one and probably would be very accurate.

Thanks for the replies!!!!

[ghostdance]

Possibly dumb question but without a centre dot on the primary, is really good collimation even possible?

(I'm really glad my primary is dotted - makes adjusting much easier, to my eye.)

[Charic]

I centre spotted a spherical mirror on my Celestron 127EQ, made absolutely no difference to the image quality after re-collimation. Some optics are just not fussed with critical alignment. With the Celestron, it just says. if you can see the mirror clips, ok,  if not return to base, or something similar ?

Dust cap, 35mm film case, Cheshire or laser, if the final  alignment and image looks good let it be. Aligning your eye is not an exact art, each and every alignment can/will be different, but your often left  thinking you can get much better, by fiddling a little longer or requiring the next 'best'  tool ? Your  first result is often the best.  I can collimate with just the dust cap, and use any other method to double check, and it all looks good.

If only collimation was automated, so many folk could avoid what they believe to be a major issue........?

[theghettostylus]

I did do it myself with the homemade cap and the views of the moon were still very, very good and clear. Maybe I'm just chasing after nothing? I may be trying to get better views when I already have the best the scope can offer. I will mull that thought over for a while before I get any deeper into the collimation side of telescopes.

[Jason D]

I centre spotted a spherical mirror on my Celestron 127EQ, made absolutely no difference to the image quality after re-collimation. 

Spherical mirrors do not need to be center dotted since all points on the mirror are equivalent -- by definition.

parabolic mirrors need to be center dotted because there is something unique about the surface center. Well, if they are not center dotted then tools can bring collimation close but you will always have to complete collimation  using a star.

Jason 

[Charic]

Chasing after nothing, maybe? I use the Astro Baby guide.

Once fully understood, and after a couple of collimation's, I find it so easy on my telescope. I'm now considering an upgrade to a 'tool-less set-up'   with   something like Bobs Knobs. In the hope that things could get easier, but I also read that   'springs' in place of rubber 'O' rings can improve the ease of collimation! I'm not sure if  springs  are the way to go, as I can visualise more scope  for movement of the primary mirror if spring loaded ( excuse the scope pun).

Were always looking for to change, what already, isn't broken, in the hope of achieving something better. When will we learn?

[Charic]

jason.......cheers, this I found out after the tweak? 

The Celestron looks better, spotted,  but that scope has some serious limits? but it  taught me very quickly about EQ setup, and assembly of components, that's why I  have no fears pulling my Skyliner  apart and re-building just to remove a hair from the mirror maybe ? Takes 30 mins if that. 

theghettostylus........what scope you have there?

[theghettostylus]

jason.......cheers, this I found out after the tweak? 

The Celestron looks better, spotted,  but that scope has some serious limits? but it  taught me very quickly about EQ setup, and assembly of components, that's why I  have no fears pulling my Skyliner  apart and re-building just to remove a hair from the mirror maybe ? Takes 30 mins if that. 

theghettostylus........what scope you have there?

I have the skywatcher explorer 130, its my second scope as I had a tasco table top 3" for about a month and couldn't really see anything so found a second hand skywatcher! So far I am very happy with the views.... It will do for now but would love to go a bit bigger on the next one.