Lasers Collimators?

[Guest]

I've seen the video below on collimating a reflector, but have also read about problems with laser collimators. 

https://youtu.be/8G98RTP6jbY

I'm rather confused... 

[johninderby]

There are good laser collimators and there are cheap ones. Cheap ones will need collimating themselves before use.  Good ones such as the Hotech or Howie Glatter ones will be spot on and are ready to use.

I use a Concentre to setup the secondary first then the laser.

Some people swear by the good old Cheshire eyepiece but I find the Concentre far, far superior for intial setup.

 

Edited May 7, 2020 by johninderby

[Neil H]

35 minutes ago, johninderby said:

There are good laser collimators and there are cheap ones. Cheap ones will need collimating themselves before use.  Good ones such as the Hotech or Howie Glatter ones will be spot on and are ready to use.

I use a Concentre to setup the secondary first then the laser.

Some people swear by the good old Cheshire eyepiece but I find the Concentre far, far superior for intial setup.

 

Hi that's good advice I had a cheap laser it's now in the bin , I have a Cheshire I collimated then star tested was a spot on Collimation then pop laser in and it said Collimation was out that's why it's in the bin I did collimate the laser collimater made no difference 

Cheshire are good once you get your head round using then astrobaby did a great step by step Collimation 

[DaveL59]

I use a cheshire myself, not found the need to spend on a laser tho I guess it might be handy for the frac if I ever have to mess with it. No plans to though, its set just so since it left the factory from what I can tell and as the second owner I've not had any issues with the views. The newts on the other hand I've messed with quite a bit with tweaks or mods and astrobaby's guide and the cheshire and lots of patience has served me just fine  

[cletrac1922]

Merlin

I use a Saxon Laser Collimator, and  had the same one for over 10 years, and it has never needed adjusting

Unless you are using your scope away from home on a regular basis, which I do, out couple of times per month with my club doing presentations in schools and primary schools, scout groups as well as monthly club meet, I very rarely need to re-adjust my 10" Flex Dob

Lot of people on here get paranoid with collimating

Not broken, leave alone, just find yourself in more trouble than started out with

Had a new member a while ago, turned up club meet with an 8" Dob, had brought second hand

For the life of me could not get to collimate, as way out

Eventually when looked down the Dob, noticed the secondary was off to one side

Using a bit of paper, measured each of the vanes, and brought secondary into center

Was a simple adjustment after that with the collimator

John

 

 

 

[Erling G-P]

3 hours ago, johninderby said:

There are good laser collimators and there are cheap ones. Cheap ones will need collimating themselves before use.  Good ones such as the Hotech or Howie Glatter ones will be spot on and are ready to use.

I use a Concentre to setup the secondary first then the laser.

Some people swear by the good old Cheshire eyepiece but I find the Concentre far, far superior for intial setup.

 

John, would you happen to have some instructions about using Concentres ?

I recently got one, along with a Hotech laser collimator.  The Concentre came without any form of instructions at all, as we're apparently all genetically coded with knowledge about using such a device!

As far as I can tell, my secondaries are pretty good, but am unsure of exactly what I'm looking for, and what to do to the secondary to correct any revealed imperfections.

The Hotech has been a joy to use on the other hand - it becomes so much easier to perform the collimation, when you can see the effect of what you're doing while you're doing it.  Have checked with a Chesire afterwards, and they seem to agree.

[johninderby]

The instructions are on the TS page.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p5506_TS-Optics-Concenter-2--Justierokular-fuer-Newtonteleskope.html

A manual for collimating your Newtonian with the Concenter collimation eyepiece:

If you hold the adjustment eyepiece in your hand, you will notice a transparent plastic disc with a central bore and concentric engraved circles inset on the telescope side at the lower end. At the other end you will find a central hole, which is chosen so small that the eye has no opportunity to avoid centering when looking through. After inserting the collimation eyepiece into the focuser you will see faint translucent rings in front of the optical components of the telescope.

♦ Collimation of the secondary mirror to the focuser for optimum illumination
This step is made with covered primary mirror. Pay attention to a good illuimination when using the concenter eyepiece. Now the secondary mirror, a rectangular mounting of the focuser supposed, is adjusted so that it appears between the circles of the collimation cicles and without offset. With the focus control of the focuser you can bring the outer edge of the secondary mirror and the matching circle to cover. Even small deviations from the ideal position are recognized immediately. By doing this, you place the secondary mirror in the optimal position to the focuser to millimetre accuracy. This step is necessary only once, you can remove the cover of the primary mirror afterwards.

♦ Alignment of the secondary mirror to the main mirror
While looking into the eyepiece, the tilting is changed by means of the screws of the secondary mirror until the bright reflection of the primary mirror in the secondary mirror is concentric with the circles.

♦ Alignment of the primary mirror to the optical axis
Shift the center mark of the primary mirror exactly in the center of the concentric circles by using the adjustment screws of the primary mirror cell. You will notice even the slightest deviation. After this, your Newtonian telescope will be perfectly collimated.

 

[Erling G-P]

5 minutes ago, johninderby said:

The instructions are on the TS page.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p5506_TS-Optics-Concenter-2--Justierokular-fuer-Newtonteleskope.html

A manual for collimating your Newtonian with the Concenter collimation eyepiece:

If you hold the adjustment eyepiece in your hand, you will notice a transparent plastic disc with a central bore and concentric engraved circles inset on the telescope side at the lower end. At the other end you will find a central hole, which is chosen so small that the eye has no opportunity to avoid centering when looking through. After inserting the collimation eyepiece into the focuser you will see faint translucent rings in front of the optical components of the telescope.

♦ Collimation of the secondary mirror to the focuser for optimum illumination
This step is made with covered primary mirror. Pay attention to a good illuimination when using the concenter eyepiece. Now the secondary mirror, a rectangular mounting of the focuser supposed, is adjusted so that it appears between the circles of the collimation cicles and without offset. With the focus control of the focuser you can bring the outer edge of the secondary mirror and the matching circle to cover. Even small deviations from the ideal position are recognized immediately. By doing this, you place the secondary mirror in the optimal position to the focuser to millimetre accuracy. This step is necessary only once, you can remove the cover of the primary mirror afterwards.

♦ Alignment of the secondary mirror to the main mirror
While looking into the eyepiece, the tilting is changed by means of the screws of the secondary mirror until the bright reflection of the primary mirror in the secondary mirror is concentric with the circles.

♦ Alignment of the primary mirror to the optical axis
Shift the center mark of the primary mirror exactly in the center of the concentric circles by using the adjustment screws of the primary mirror cell. You will notice even the slightest deviation. After this, your Newtonian telescope will be perfectly collimated.

 

Thanks John, I have read those, but still find them unclear. Some illustrations would have been so much help.  For example; I adjust focus so that one edge of the secondary mirror lines up with one of the circles of the Concentre, but then what - is the secondary supposed to form a perfect circle within the Concentre's circles ?  Mine are ever so slightly oval I believe, and what adjustment should be performed on them to correct it - is the mirror to be twisted ?    Adjusted with the 3 collimation bolts ?   With the central big bolt ?    With the above instructions, they're basically telling me I can get the placement perfect, but not how to do it.

[johninderby]

The secondary should look like a perfect circle that that looks like this. You may have to rotate the secondaty. 

You will have to use the centre bolt to allow the mirror to move up or down to centre it in that axis so slacken the three bolts way off to allow you to adjust with the centre bolt. Once the mirror is right up or down then tighten the three bolts until just touching and  rotate the mirror. From then on it’s normal collimation which should only require adjusting the three bolts.

Edited May 7, 2020 by johninderby

[Erling G-P]

7 minutes ago, johninderby said:

The secondary should look like a perfect circle that that looks like this. You may have to rotate the secondaty. 

You will have to use the centre bolt to allow the mirror to move up or down to centre it in that axis so slacken the three bolts way off to allow you to adjust with the centre bolt. Once the mirror is right up or down then tighten the three bolts until just touching and  rotate the mirror. From then on it’s normal collimation which should only require adjusting the three bolts.

Thanks John; much appreciated!     That photo on TS's homepage would have said more than a 1000 words!

[Guest]

Thanks for everyone's feedback. 👍