collimation tools

[Paul1]

Hi,

I am orientating to buy a new telescope , and have had my eye on the Epsilon E130D F / 3.3, Astro Graph. Now I know that the collimation of such a fast system should be very carefully done . What collimation tool can I use ? Because there are so many.

Regards Paul

[WireD64]

Get yourself a collimation cap and a cheshire collimator, that is all you need to get going.

Once you've got a bit more experience collimating then move onto laser collimation if you wish. But you will find laser collimation brings a whole other set of issues, as the laser will also need collimating and even the method itself can seem a bit flawed. This will split opinion i'm sure.

[RT65CB-SWL]

+1 for the above post.

Somewhere on the astronomyshed.com website, Dion explains & shows you how to build a simple 'V-block' and collimate a laser collimator.

[Paul1]

Thank you for the information gentleman.

Regards Paul

[Jason D]

Get yourself a collimation cap and a cheshire collimator, that is all you need to get going.

Once you've got a bit more experience collimating then move onto laser collimation if you wish. But you will find laser collimation brings a whole other set of issues, as the laser will also need collimating and even the method itself can seem a bit flawed. This will split opinion i'm sure.

You can't generalize. If you purchase a cheap laser collimator then you are right -- most likely it will require collimation. But if you purchase a quality laser collimator such as a Glatter then it will never require collimation.

What did you meant by "even the method itself can seem a bit flawed"?

Jason

[WireD64]

Quite right you are, I was making an assumption about the laser.

My assumptions were he'd be looking at a basic laser to start with as he didn't actually mention them, and with that assumption in mind those cheap laser are no good for collimating the secondary, I have a cheap laser and I only use the barlow technique on the primary once I've got as close as I can by eye using the cheshire

For the OP to understand further here's a link to a good youtube video explaining what I was calling flawed

[Dave In Vermont]

I am amazed to see that no one has yet mentioned Astro Baby's incredibly clear and easy-to-understand collimation guide. So I will. Written by a member here, she has done a fantastic job. One thing you will notice is her excellent pictures showing the difference in the off-set that fast-Newtonians have. This is often missing in other guides, and causes a great deal of confusion. Here you are:

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

One thing you will learn is that after you have successfully collimated your scope, you will wonder what all the worry was about. It becomes so simple that you can do it without even thinking about it! You, like myself, may find that you actually enjoy it. I currently use a laser and a Cheshire Sighting-Tube. I enjoy it when they both agree with each other - which they always do and should. But whichever tool you like best, you'll find it takes but a minute or two.

Hang in there,

Dave

[Ju Piter]

I am amazed to see that no one has yet mentioned Astro Baby's incredibly clear and easy-to-understand collimation guide. So I will. Written by a member here, she has done a fantastic job. One thing you will notice is her excellent pictures showing the difference in the off-set that fast-Newtonians have. This is often missing in other guides, and causes a great deal of confusion. Here you are:

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

One thing you will learn is that after you have successfully collimated your scope, you will wonder what all the worry was about. It becomes so simple that you can do it without even thinking about it! You, like myself, may find that you actually enjoy it. I currently use a laser and a Cheshire Sighting-Tube. I enjoy it when they both agree with each other - which they always do and should. But whichever tool you like best, you'll find it takes but a minute or two.

Hang in there,

Dave

i agree dave seemed really scary at first but i used astrobabys guide and personally think it is the best out there,easy to follow with great pictures and the offset with fast newts was something that nowhere else on the net shows which confused me before i found astrobabys guide as i thought everything needed to be central but now know that the offset of the collimation cap or cheshire reflection is normal.i too actually like collimating my scope now

[BritAngler]

The first time I collimated my SW200P it took me about 2 hours (including a break part-way through) to do both mirrors; they were both way out of alignment. Now I could do the same job in 15 minutes or less - practice makes perfect. Forget the laser collimator (the magic word 'laser' doesn't mean it's better) and just go with the Cheshire and collimating cap. Nowadays I check collimation before any planned viewing session and only really start adjusting things if they are getting too far off alignment. Near enough is usually good enough

Usually it's only the primary mirror that needs adjusting, the secondary mirror maybe 10% or less of the time. A couple of things I use which I find very useful when adjusting the secondary (and are mentioned in Astro Babys' guide) are a piece of cardboard with white paper glued to it which can be clipped to one of the vanes to block off the primary mirror, and a square of orange coloured photo-paper to create a background around the secondary.

[cjdawson]

Rather than shell out for chesire's or laser collimators.  It's worth trying the simple option first - use a ball bearing with a light shining on it.  It'll give you a point source.  Once that's in good shape, get out under a night sky and finish the collimation job on real stars.

I personally have an artificial star that I can use, apart from that, I don't use anything special.  Just take the time to do it on real stars and it's job done.

[Paul1]

Thank you that helps me forward.

Regards Paul

[abodee2]

At first when I got my newtonian I was terrified about collimation based on what i had read online. However, the first tool that i was recommended by my local telescope store was a Baader Laser Collimator which I found extremely easy to use and worked very well. You'll get a range of opinions, I think the most common one is to use a cheshire. Collimation is actually really simple, watched a simple youtube video of collimating a newtonian with a laser collimator and it probably took me 2 minutes to do myself - and i'm not really bright at all! 

I'll link you to the one i got: http://www.firstlightoptics.com/other-collimation-tools/baader-laser-collimator.html

It's a bit expensive (£67.50) but you can be sure it's well made and my laser came already precisely collimated, been using it ever since.

Good luck!

thanks,

Ali

[abodee2]

This is the video I followed

[Jason D]

For the OP to understand further here's a link to a good youtube video explaining what I was calling flawed

In the video the following observation was explained:

1- Adjust the secondary mirror until the laser beam strikes the primary center

2- Physically rotate the secondary mirror

3- Adjust the secondary again using only the tilt set screws until the laser beam strikes the primary center again

The above observation is correct. In the video, it was explained that lasers "lie" because the secondary mirror was re-adjusted to direct the laser beam at the primary center knowing that it was rotated!!!! The claim is if the secondary mirror can be readjusted with a known rotational "error" then laser collimators must "lie".

Here is the problem with the above interpretation: A similar experiment can be done but instead of rotation, let us raise or lower the secondary mirror via the central bolt. It is possible to redirect the laser beam to the primary center by adjusting the tilts set screws when the secondary mirror is higher or lower. We all know this is possible. Does that mean laser collimators "lie"? 

Here is what is going on: The observation described in the video is known and old -- at least to those who have deep understanding of collimation, When the secondary mirror is tilted via the set screws, its reflective surface planar movement  in 3D space can be broken up to several rotational components of which one is around the central bolt axis. This is counter-intuitive. Yes, the secondary mirror surface plane can be rotated slightly around the central bolt axis without physically rotating the secondary mirror. So, when the secondary mirror is physically rotated by a small amount, the rotation can be undone my using the tilt set screws. This works only for small rotations. That is why in the video when the rotation was too much, the person behind the camera could not redirect the laser back to the primary center via tilting.

One common misunderstanding of laser collimators is the following: Typical laser collimators can't tell you if your secondary mirror is centered under the focuser. You can shift your secondary mirror up, down, left, right, and even rotate it slightly, yet you can always succeed in redirecting the laser beam to the primary center. There are countless threads in astro forums where the OP would express frustration because he/she completed collimation via the laser collimator yet only 2 out of 4 primary mirror clips are visible. The laser collimator was never intended as the tool to use for centering/rounding the secondary mirror under the focuser. Think about it!!!! if the laser beam only interact with a tiny spot on the surface of the secondary mirror and does not interact with the secondary mirror edge, how can it tell you if your secondary mirror is centered or not? A sight-tube is one of the easiest tools to use for centering/rounding the secondary mirror. Once the secondary mirror is centered/rounded then the laser collimator can be used to align the focuser axis followed by the primary (or optical) axis.

Jason

[jetstream]

We should all listen to this guy ^^