The HoTech laser collimator with its patented self-centreing adapter (SCA) mechanism allows precise, repeatable installation in all brands of telescope focusers.





The SCA mechanism serves three critical functions: It's expansion rings accommodate almost all focuser's manufacturing tolerances, it automatically centres the adapting laser and provides at least two evenly distributed circular contacts on the focuser's inner tube surface preventing the laser from pivoting.

Once the 'slop' factor is removed you can quickly and precisely collimate your telescope with confidence.


Collimation for your SCT

Traditional laser collimators are not suitable for collimating SCT telescopes but the Hotech laser's SCA mechanism and detailed faceplate provide the accuracy and repeatability necessary for even SCT collimation.

Commercially made SCT telescopes all have slight optical and mechanical alignment errors. The error typically is in the centreing of the secondary mirror. Consequently, when a laser is installed its beam will seldom return dead-centre, even though star testing might indicate perfect collimation. In addition, the secondary mirrors convex shape magnifies any error by approx 5 times. Typically a well collimated SCT will return a laser beam at around 0.125" to 0.250" off centre. In order to compensate a different approach is required than when collimating a Newtonian:

An SCT primary mirror is fixed but you can collimate by adjusting the secondary mirror to a point parallel to the optical axis. There is a one-time-only preparation required for SCT laser collimation. First, after a star collimation (still the most accurate method) install the SCA laser collimator then mark the laser spot position on the target grid of the collimator. Then, when you next check for collimation, look to see whether the laser spot falls on the mark. If not, adjust the alignment screws on the secondary mirror to move the returning laser dot to the mark. At this point you will have set the telescope's collimation back to a known position. Job done!

Please note, the 2" model is the same 1.25" SCA laser collimator supplied with a SCA 1.25"-2" adapter.

For further details on this and other telescope collimation tools please see our website.

Video of the SCA Collimator being used on a Newt

YouTube - Newtonian Collimation using SCA Laser Collimator

That looks very interesting ,!!darn firms network wont give me access to u tube lol .

the "self-centring" looks really good - I gave up with my baader laser because of the focusser slop problem.

is the laser "user collimatable"?

No, but the Hotech laser is not one of the off-the-shelf 'pointer' lasers used by most competitors. Hotech are an opto-electronics company with over a decade of experience designing and manufacturing laser modules for various industries. The laser used in their collimator has been specifically designed with a narrow beam radius and is precisely centred during manufacture. It will not be necessary to re-collimate the laser collimater.

HTH

Mel (Astro_baby) is currently using one of the Hotech laser collimators with her Newtonian and will be posting a report soon

She's not taking it apart to see how it works is she...

I find with focusser slop that if I take the scope off the mount, lay it flat on a blanket with the focusser pointing stright up, that with the weight of the collimator it sits better in the focusser without gravity trying to pull it down, I know that some collimators can be fairly heavy

No ..... At least I don't think she is

Focuser slop is not an issue if using the barlowed laser method....for the primary. This to my mind would help with the secondary alignment with regard to focuser slop.......except for the fact that its moot anyway as the Eyepiece has no self centering adapter and thus will be pushed to the side by the thumbscrew or compression ring. After all one is collimating the scope to centre the lightcone on the EP. Hotech should bring out a 2-1.25" focuser adapter with the self centering. That way colimating with the hotech laser would be collimating to the centre of the focuser hole and the hotech adapter would position the EP in the centre too. Without a centred EP there is no point in a centred laser

Sounds interesting Steve. The one thing thats put me off laser collimators so far is that I don't want to end end "chasing my tail" collimating a collimator. Looks like this has the anwser.

but if you are imaging, you CAN use the Hotech 1.25" or 2" to T-Thread adapter:

don't agree - I would rather have an e/p off to one side in a well collimated scope than an e/p off to one side in a badly collimated scope unless the e/p was "off" in exactly the same way as the laser (whih seems unlikely. I think(?)

ps red dwalf - like the idea of laying scope down on blanket but wife might think I'm up to something. Smeghead

Yes, I doubt there is a better way of ensuring the imaging chip is precisely centred on the optical axis. Solid as a rock too!

Kniclander,
Either way the eyepiece won't be central to the optical axis/light beam and any off-axis abberations will be magnified!!
Sometimes you can't win!!!

Okies - heres my first report on the Hotech Laser Collimator. As you know I am a Newtonian fan and dont own an SCT so I could only test it on my own scope.

Heres the report.......


Seeing the light……….
HOTEC Laser Collimator


People may be surprised to see me review a laser collimator given my well known dislike of lasers. Generally speaking laser collimators tend not to work well without a fairly high precision focuser as the focus slop created by most focusers generally leads to inconsistent results and very often to large amounts of frustration for the user.

The HOTECH collimator gets over these problems with a rather ingenious approach which allows the laser to ‘self centre’ itself. I was intrigued by this and fortunately I had the opportunity of having one to test kindly provided by First Light Optics the sole UK distributor. So would this unit make me want to own a laser collimator ? Lets see…….

First Impressions


The HOTECH laser collimator comes in a rather natty box in a kind of black faux crocodile skin. Inside the box the collimator rests on a die cut foam insert together with its battery which is an unusual size (CR123 A) but readily available from most photographic stores. The whole presentation is extremely slick and oozes quality.

The collimator itself is made from a combination of metal plus machined high grade acrylic plastic. The overall impression of the unit itself is one of great quality and precision. This view was only reinforced by use and the results it showed.

Something to bear in mind is the HOTECH collimator is a little different to most and so a good read through of the supplied comprehensive instructions is to be recommended before you play with it. Sorry guys I know most of you love to play first but on this one I really suggest reading the book BEFORE you play.

Self Centering – How its done

The unit, rather than rely on the telescope focusers thumbscrew lock, relies instead on an ingenious mechanism whereby several thick rubber strips on its nosepiece are compressed into the focuser by a compression ring on the collimator. These can be seen in the photographs. The effect is that the collimator always finds the exact centre of the focuser which provides very accurate and reliable collimation.

Testing showed the laser to be perfectly collimated to itself straight out of the box. The laser is bright and almost completely circular in shape unlike many other laser collimators which show a rice grain shape and are often inaccurately collimated. There is no brightness adjustment on the unit which I personally found to be little loss myself. The laser is switched on and off by twisting the end cap of the battery compartment. If I bought one of these I think I’d be inclined to keep the battery out of the unit when not in use to prevent accidental switch on.

To test the unit I first applied it to my own Sky-Watcher 200 which was already in collimation using a Cheshire to see if the laser would agree with the Cheshire. Most low cost lasers never do. To my surprise the HOTECH unit showed a slight variation but was almost spot on. A small tweak of the secondary and the primary bought the scope to collimation with the laser and a check with the Cheshire showed perfect collimation indicating my Chshire was slightly out.
I then decided to upset the collimation completely and start from scratch to see if the HOTECH could do the job. Obviously you still need a sight tube or collicap to align the secondary to the focuser and check that the secondary is true but beyond that I used the HOTECH and found on examination with the Cheshire that collimation was always very close – the small differences would be due to the Cheshire itself and my eyes rather than any fault in the HOTECH collimator. My own Cheshire is not nearly so well engineered as the HOTECH product.

One of the neat features built into the unit is that the laser grid faceplate has three thick lines marked onto it – these correspond to the primary mirror collimation screws. With a little practice you can immediately see which screw needs adjusting. It’s a thoughtful touch and furthers the impression that this piece of equipment has been thought through very well.

The unit will handle both 2” and 1.25” focusers. The 2” nosepiece is held on to the main collimator body using the same self centring technique that the unit uses to lock itself to a focuser so if you have a 1.25” focuser you can still take advantage of the units self centreing capability. I had planned to test the unit in a slightly less sophisticated scope but unfortunately the scope on loan had to go back before I was ready.
As a result I was only able to test the unit against my own Sky-Watcher 200 but on that basis I was very pleased with the product.


Conclusion

If you like lasers or are considering getting one then the HOTECH is indeed worthy of serious consideration. The list price is expected to be around £120 which I would consider very fair for such a high quality product.



note; Re-edited to take out my terrible typing - pic of the unit on loan below.

interesting review, AB - you clearly know your stuff and your guide to collimation was invaluable to me. One query - where there was disagreement between cheshire and laser, why do you conclude that it was the cheshire that was out, not the laser?

Ahhh - because the Cheshire is quite a cheap unit and it relies on my eyeballs always being in the same position is my guess. The Hotech is a bit more ruthless on accuracy.

In a nuthsell I could look in the cheshire and believe collimation to be ok. The Hotech might suggest a small bit of tuning ( always to the primary). When the tuning was done the Cheshire would still show ok which would tend to make me think its my eyeballs at fault or that the accuracy is higher than the cheshire could acheive.

I should add that the Hotech was used plugged in with its 2" adapter whereas my Cheshire relies on the moonlite 2" to 1.25" adapter which while very good is not self centering. Its compression ring is good enough for most things but obviously introduces a small error againts the Hotech with its self centering system.

Thats all I can suggest really as the Hotech showed VERY consistent collimation of itself ( I tested it by rotating it a few degress at a time in the focuser while locked and it was always bang on target).

I would also suggest that secondary mirror rotation is the real peril with a laser. Its easy for rotation errors to creep in which will give a good laser result even when the secondary is badly misaligned to the focuser - thats why you have to get the secondary close using a sight tube or colicap and recheck after collimation is completed.

I havent deceided to buy a Hotech yet - if I were going to buy a laser it would be the one I'd buy - I just liked its quality feel and the fact its been properly engineered.

My reluctance isnt much to do with the unit - more to do with me having promised my partner I'd not go spending more cash for a while

Unless a mask with a "offset" hole is used on the secondary or a collimating/ cheshire eyepiece used, any laser collimating tool will NOT confrim the correct positioning of the secondary.
It's gratifying to note on the U tube video mention is made of the superimposition of the laser spots on the secondary mirror....

thanks AB - interesting. Like you, I am also "on the wagon" when it comes to astropurchases so i might add this to the list of thing I can't have.

The Hotech laser collimator is now fitted with a proprietary cross-hair laser. The crosshair model displays a precise laser centre dot with four extended laser lines for easier and more intuitive centering.



During the secondary mirror collimation, a single dot laser projecting on the approximate center of the pre-loaded donut can be difficult to identify if the laser dot is exactly on the center. The crosshair laser can easily help user to adjust the secondary mirror to point the laser on the exact centre with the help of the crosshair line. During the final primary mirror collimation the returning laser dot often hides inside the laser exiting hole when centred whereas the crosshair is visible at all times.

Click here for a video tour on YouTube.

Also, the current £-$ value makes this new laser available at almost the same price as the previous model.

Interesting thread. I've posted a note to Hotech asking them to confirm (in their opinion) whether their device approaches [note] the levels of collimation achieved by the cheshire.

They suggest it can - proof indeed that if you eliminate the off-centre problem by the 2" to 1.25" reducer / pinch screw, and stand well back (e.g. 3 feet) from the peep-hole to remove parallax errors, the cheshire device is still a very viable tool for the most accurate colimate - assuming..it's well made of course !

Is it actually possible to see anything through a peep hole at 3ft?!!!

As im an SCT fan be good to see a review on collimating a SCT, see if it give consistant reviews.

Enjoyed your review Mel, can you borrow my SCT and review it on that

I recently bought a laser collimator and an Orion self centering adaptor, then Hotech come out with this which is really a combination of the two. If it works as well as my gear it will be an awesome tool. My collimation looked ok using just the laser, but when I added the centering adaptor it was an inch off the centre spot. Centred the beam then dropped the barlow in, a quick tweak and it's done.
If I hadn't just bought this gear I would have had one of these like a shot.