Laser eyepiece collimator

[nikooo]

H guys, I'm curious should I buy laser eyepiece for collimation?

[Jim L]

They can be handy for aligning the secondary axis with the center mark on a Newtonian, and for checking the focuser alignment on a refractor.

Placed into a Barlow a laser can also be used to align the primary mirror axis with the focuser axis. Without a Barlow the results can be far less reliable.

So I’d say yes, it’s worth having. You don’t really need anything super fancy, but be prepared to collimate it if it’s not well aligned.

Alternatively, a combination sight tube like the one sold by CatsEye is an excellent choice, and adds the capability of centering and squaring the secondary mirror in its holder.

[pipnina]

I am a fan of the laser collimator, however I also believe they must must must be used *with* the correcting lenses and other accessories on the focuser. All those joints between focuser and camera can have small mis-alignments which you want to take into account when collimating your scope, so just take the camera off and (if possible) screw the collimator on for the best possible result (use collimator with corrector/oag/filter wheel etc)

You also will want a v-block or two supported bearings to collimate the laser, as it is unlikely to be perfectly collimated itself from the factory.

[Guest]

Its the only thing i use.  I did have to collimate it initially but have not had to mess with it since.  Collimating the laser can be tricky and take some time but it can be done fairly easily by making small adjustments and being patient 

[iapa]

The ‘beauty’ of collimating lasers is that they themselves need collimating.

Here’s one way: 

I tried this on a couple of these (£+) and it work OK - then I just settled for a Howie Glatter Collimator (£+++) before another company took over manufacture, I can’t comment on the current quality, but the original was excellent.

 

 

[bosun21]

I bought a Hotech 2” laser collimator and it arrived perfectly collimated. I use a combination of the laser, cheshire and a cap. I use the laser on its own before each observing session once my scope is in situ.

[Spile]

I prefer to use a cap for the primary and a Cheshire eyepiece and sight tube combination tool for the secondary.

[Mr Spock]

I use a laser on my 12". Takes just a few seconds at the start of each session.

I have other such as a Cheshire etc, but they are useless in the dark and from five feet away. The 12" has a very long and bulky tube - put the laser in and get down behind the tube where the adjustment bolts are.

[John]

Barlowed laser collimation is worth a try:

Rear View Barlowed Laser Collimation (smartavtweaks.com)

[Louis D]

A laser collimator (with or without the 45 degree window port) is also useful for getting the primary on a truss Dob back in the general vicinity of where it should be if it has shifted on its support pads and sling during transport.  You just crouch at the back of the scope and adjust bolts until the return spot coincides with the outbound spot on the face of the secondary mirror.

[JOC]

I bought a laser and a Cheshire eyepiece I tried both, I use the Cheshire out of choice if I need to collimate the telescope.  I'd say don't waste your cash on a laser when a cheap and cheerful Cheshire does all and is far less prone to it's own foibles (see video above).  Whatever you use it is worth checking out how to fit the sight centrally in the eyepiece holder.

[AstralFields]

In my experience, lasers cause a lot more problems than they solve (including for me until I learned collimation properly).

With this being said, I have three tools to achieve very precise collimation on my 8"

1) Digital Caliper to ensure that the secondary mirror holder is exactly in the center of the tube. This has to be done just once, when I clean the secondary and take out the entire spider.

2) Cheshire combo tool for secondary placement, offset and collimation so that the entire primary is properly reflected. Once this is properly done and tightened, it doesn't fall out of collimation even after many drives with my car.

3) Laser for the final primary collimation. I have collimated the laser but even so, every time I put the laser in, it ends up a little bit someplace else on the target center spot of the primary. At the beginning I tried to collimate the secondary each time (big mistake!) and once I spent an hour in the dark trying the laser and cheshire to agree. (big mistake! Always collimate the secondary in daytime). Maybe if I had a paralizer and put some tape around the bottom tube of the laser for a better fit it would be more accurate but since I have the cheshire I have not bothered.

I just wiggle a bit the adapters until the laser hits the primary center spot and after that I collimate the primary. My 8" Sky-Watcher has not needed it for three weeks now - star tested. It just holds really well even after driving the scope with my car on a somewhat bumpy road.

The laser is not really needed but it is much faster as with the cheshire I would have to check collimation, go to the primary screws to turn them, check again etc etc... not very comfortable in the dark. If I didn't have the laser, knowing what I know now and how well it holds collimation.. I would never even buy it again. Thinking about it, maybe I will sell it.

Edited July 20, 2023 by AstralFields

[wookie1965]

I use a Cheshire even in the dark I just shine a red light at the 45° window 

[mapstar]

I use a hotec on the truss dob. It takes litterally a couple of minutes 

[wookie1965]

2 hours ago, mapstar said:

I use a hotec on the truss dob. It takes litterally a couple of minutes 

Its not like you can check the focuser and then tweak the primary need arms like a orangutan 😃

[Piero]

I use a 2" Howie Glatter (650nm) with 1mm aperture stop attachment and collimate both focuser and primary, also matching the 1/4" white triangle mark on the primary against the concentric rings projected by the laser onto the attachment surface.

The tublug is used sometimes, when I am tired.

Other times, I use a 2" Catseye telecat for both focuser and primary alignments. This tool is also used for positioning the secondary correctly. This is easy for me as I don't value the theory of "benefitting" from an excessively small central obstruction at all.

[moggi1964]

On 23/07/2023 at 08:13, Piero said:

I use a 2" Howie Glatter (650nm) with 1mm aperture stop attachment and collimate both focuser and primary, also matching the 1/4" white triangle mark on the primary against the concentric rings projected by the laser onto the attachment surface.

The tublug is used sometimes, when I am tired.

Other times, I use a 2" Catseye telecat for both focuser and primary alignments. This tool is also used for positioning the secondary correctly. This is easy for me as I don't value the theory of "benefitting" from an excessively small central obstruction at all.

Howie's setup is exactly the one I use though I only used the TuBlug once.  Super easy, super consistent.

I got my laser from Howie directly when he came to NEAF in New York and he talked me through how it was constructed and how he had never had to recollimate his. When you see the way it is built you can understand why. Howie was a lovely chap (sadly no longer with us) and his wife, a lovely lady.

Here's an image of the rings projected onto my attic ceiling for anyone who's never seen this setup. It has a squares option too though I never did figure out what that is for.  These are clearly not representative of what it looks like when you use it properly with a mirror 😀

 

I've also used Cheshire which were fine for daylight collimating.

[bosun21]

I use a concenter to set my secondary mirror then a Cheshire. I finish off with a 2” Hotech laser which is perfectly collimated. The Hotech collimation is repeatable and takes seconds to check the collimation on my 12” before each observing session.

[AstroMuni]

On 22/07/2023 at 21:46, wookie1965 said:

Its not like you can check the focuser and then tweak the primary need arms like a orangutan 😃

And this comment is from a Wookiee 😉 LOL