Newtonian Collimation using SCA Laser Collimator

[m4n52k10]

i dont have a donut what should i do

[FrauGrimhild]

Laser is fine for last part of collimation (adjustment of primary) but not for adjustment of secondary. The laser can 'lie', here; i.e. just because laser is spot on primary ring marker does not guarntee secondary is at desired angle to optical axis. The only way to ensure perfect adjustment of secondary with a laser is to employ a diffraction grating.

[biggrex]

doesn't work with focusers that have a recessed tube circumference of more than 1.25", my focuser only has a 1.25" ring that is about 1/4" wide, so my new hotech is worthless, it moves around more than any screw tightener would!

[HoTechUSA]

@biggrex,

Don't really understand what you mean by more than 1.25" focuser circumference. I think you try to address three issues in one sentence.

1. Focuser fitting issue:

The compression ring can expand to fill the standard mfg. focuser opening tolerance +/- 0.05". If it still doesn't fill the opening, it is the focuser's problem where the mfg. has VARY sloppy quality. Upgrade one if possible.

[biggrex]

@HoTechUSA

It's difficult to explain without a photo. Essentially the eye focuser is not 1.25", maybe it's a cheap design, but I would say the tube itself is closer to 2" and then it has an inner ring on the end of the tube where you insert the eye piece that is 1.25", but the ring is right on the end, so the compression area on your collimator is really just dangling and surrounded by open air. I finally just pushed the collimator and held it pushed in so it was flush and didn't rely on the..

[biggrex]

@biggrex ...rely on the compression ring, just my hand keeping the collimator pushed into the focuser as far as it would go and rest it there steady while I made the necessary mirror adjustments.

[HoTechUSA]

@biggrex,

Is your focuser a 2" version with a low-profile 2" to 1.25" adapter inserted? If this is the case, you can either find a new 2" to 1.25" adapter that does not have the recess for more adapting space and inner tube adapting area, or upgrade to a 2" collimator to collimate straight on the 2" focuser. I only wish you can utilize the SCA mechanism fully when collimating.

[HoTechUSA]

@biggrex,

2. Unstable movement after installation:

It is possible that the focusing gears are loose causing the entire assembly to move even if the collimator is secured in the focuser. Please double check the movement source.

3. Focuser inner contact surface too shallow (1/4”?):

Many mfg. cut corners to save material by shortening the depth of the focuser. Try to upgrade a new focuser.

The quality of the focuser is out of our control.

You can email me for faster response. Thanks.

[waheex]

good video , but there is no compressorring on the 1.25 inch collimator? instructions are different with this model. Do you tighten the grip ring before you insert the collimator into the focuser?

[HoTechUSA]

@waheex,

You can either tighten slightly on the compression ring first for a snug fit, then tighten further down to secure the collimator in the focuser. Or you can just insert the collimator in the focuser, then tighten the collimator. The mechanism should keep the laser from wobbling in the focuser for a repeatable collimation.

[waheex]

great video, as im new to this kind of theng

[spacexposed]

is that a 10' or 12' dobsonian??? can't quite make it out....

[HoTechUSA]

This is a Meade 10' LightBridge.

[spacexposed]

genius product..well worth the $150

[g00glian0]

I thought that was a great tutorial! Very clear (for not being a native speaker) and straight to the point. I never knew one of these existed before. That looks much easier than the 35mm can I have been using! Now I know. Thanks for posting.

[clubsport911]

I cannot think why Hotech invite questions, then fail to answer them ? Why might that be ?

[HoTechUSA]

@clubsport911. Please email me. I do reply emails in a timely manner. This post can only take a few characters for a short answer which is very frustrating to give you a complete answer in several posts. Sorry again for not reply promptly.

[hreasons]

Thank you very much for making these videos. I've just bought the 2" model (actually it's being delivered tomorrow) so I am looking forward to collimating both my 12" and 8" Newt's.

[clubsport911]

Still awaiting answers...

[HoTechUSA]

Hello clubsport911, Sorry for not responding your questions in a timely manner. I don’t’ login this account too often and have been extremely busy developing new collimation technologies (see the new Advanced CT Laser Collimator for Cassegrain telescopes at our website). Your answer is quite long, I will do this in two parts. It is better to email me for a faster reply too.

[HoTechUSA]

@clubsport911

Q1: despite extra effort, you can still get precise collimation level with a Cheshire …

A1: Every instrument has its own errors, and it all depends on the user’s expectation or acceptance of tolerance, and how deep the user’s pocket has. If you expect “no” or zero misalignment, the collimation instrument will require extensive technologies to achieve the final 1% perfection which can be millions of dollars like what JPL and NASA is spending.

[riff5000]

I recently bought the crosshair 2" SCT collimator. When I rotate the collimator in the drawtube the laser moves in a small circle on my primay. Does this mean the collimator is our of alignment or is it possible I have a focuser that is out of adjustment? Any ideas? Thanks.

[sixchiensblancs]

Hi there, I don't know for sure, but I wouldn't think that your collimator, if it is new, is out of alignement because they are factory alligned, unless it was dropped or hit. More likely your focuser is the problem and that's should be easy to adjust, make sure it is tightly square with your scope. Also, Perhaps call the people who sold you the collimator and ask them a few questions? Anyway good luck, and clear skies!

[pluckyfella7]

I have compared the Tectron collimation tools and this laser collimator for my 13" Dob. If you're collimating an open truss scope alone, you don't have to keep going up and down, primary mirror to focuser, when you adjust the primary mirror, because you can see the laser beam dot on the secondary and in the hole. The laser collimator is a lot quicker and more accurate in the dark; its tube properly centred. The focuser's screw offsets the sight tube a little; the Cheshire's ring needs light.

[LUFC994]

I know a girl who uses hoetech. : )

[rastamaniakTHC]

so?

[bluesand22]

The compression ring is a good idea. My laser ( different manufacturer ) moves off centre when the retaining thumb screw is tightened making it useless really.

[rdj200]

Hello,

i have obtained this good collimator but unfortunatily my main mirror does not have a center mark or a donut shape, how i can make one please.

thank you

[HoTechUSA]

Cut out a piece of paper with the same dia. of your main mirror. Fold it in half twice look like a flat cone shape. Cut the tip of the cone to relveal a center hole. Get a binder re-enforce sticker ring at OfficeMax.

Take out the primary mirror, lay the paper on top of it and use the cut out center hole as a guide to stick the ring sticker on the exact center of the mirror. It is critical to place the donut in the middle. Try to simulate the process in your head before your do it.

[clubsport911]

My understanding is that despite extra effort, you can still get precise level of collimation with a Cheshire collimator / sight tube system as there is no inherant potential misalignment between the mechanical and optical (laser) axis. Is this your view ?

I recently collimated my F4.5 scope (16") and when finished, had it checked with a Glatter holographic + barlowed laser system. There was no difference. What are the advantages of the hotech system ? I'd appreciate your thoughts

[HoTechUSA]

Your questions require extensive answers. Please be patient with me. I will soon reply you. Thanks.

[clubsport911]

Many thanks - I'm looking forward to your answersd...

[clubsport911]

....still waiting......

[HoTechUSA]

@clubsport911 Cheshire collimator is a great economical tool for most amateur astronomers. With precision custom machined and matched to your own focuser fitting, you will have great collimation result (assuming your other optical components are also up to you specification). But the combination of a mass produced Cheshire and a mass produced telescope can spell collimation nightmare.

[HoTechUSA]

@clubsport911 It can be very difficult to confirm repeatable collimation on each attempt from the “potential misalignment between the mechanical and optical axis” as you mentioned. This is why it is difficult to answer your question without first hand measurement of both your instruments and exact performance expectation.

[PragmatistForToday]

@HoTechUSA

I think clubsport911 has been pretty patient, any answers?

[nasdrasil]

Hello,

I'm thinking about buying a Hotech collimator for my 8" Newton. My focusser is 2" but I always use the 1.25" adapter for my webcam, eyepieces etc. What would be the best buy for me? the 1.25" version or the 2" version?

And if I want to use a barlow to collimate my primaire mirror, does it hurt to take the crosshair version of the collimator? Or am I better off with the normal dot version for barlowed laser collimating?

thanks in advance!

[HoTechUSA]

It is always best to collimate using the corresponding focuser size collimator to reduce any possible errors that might cause from additional none-SCA adapter. 2" version will be ideal in your configuration.

Barlow the crosshair version will work just fine. The barlow lens expands the laser dot large enough to cover the center donut on the primary to cast a returning shadow. It will have the exact same effect using a single dot version. Thanks for the great questions!

[nasdrasil]

Hey, thanks for answering my questions! I do havea few more though.

I will follow your advice then on buying the 2" version. I understand that it comes with an adapter to 1.25". So if I'm done collimating, is it possible to use this adapter for holding my eyepieces/camera etc? And I'm using a Moonlite focuser which has a drawtube with a compression ring. Will I encounter any trouble when putting in the SCA adapter?

Sorry for all the questions, but better safe then sorry :-)

Thanks again

[HoTechUSA]

The 2" to 1.25" SCA adapter only accepts 1.25" SCA adapter because there is no thumbscrew to lock the proposing eyepieces/camera unless the adapting equipment also has a 1.25" SCA adapter. The opening is a high precision machined 1.25" straight tube.

Moonlite builts good focusers. There should be no problem using the SCA adapter. Make sure you reliease the compression ring (keep the compression brass ring inside the focuser groove) before adapting the SCA collimator.

[nasdrasil]

I think that's about it. I'll go ahead with the 2" version. You guys should consider making SCA adapters which screw into eyepieces or camera's ;-)

Anyway, thanks again for all the info you gave me. Fast and good support. Keep it up!

Jordi

The Netherlands

[HoTechUSA]

We have SCA T-Adapter for SLR camera. Check it out on our website. It also receives great reviews by several astronomy magazines, forums, and web sites.

[jibbs001]

thanks for answaring me questuion , and i have a reflector telescope and yes i have a 0.965'' focus and i have an adapter to which is 1.25'' , thanks for helping again

[jibbs001]

thanks for thisvery good clip , but i need som help with my telescop , it's called optison star 1000114 || , with toll do i need to buy, i see that that tool you use doesn't fitt into my telescop , thanks for helping!!

[HoTechUSA]

I am unable to find your telescope "optison star" in the web search. Is this an old telescope using 0.965" focuser? It is reflector or a refractor telescope? If anyone knows about this scope please help. Thanks.

[WiIfredOwen]

That was excellent video. I have two collimator tools for my 10" Newtonian. I tried your method last night, and I had no issues with it. However, when I then looked through a collimator tool, the secondary mirror was out of alignment as well as the primary. Something tells me the laser is more accurate.

[rehoboth21]

I recently bought one of these collimators and I am having lots of trouble getting it into and taking it out of the 2" crayford focuser. I do everything shown on the video but the collimator is still very hard to get in and out. Any suggestions or help?

Thanks

[HoTechUSA]

Please double check the brass compression ring in your 2" Crayford focuser is fully expanded against the inner groove to leave a good inner 2" clearance for the SCA adapter to be insert and release. If not cleared, the brass ring tends to catch the adapter. If you have further questions, please contact me via our contact email. Thanks

[HoTechUSA]

Always doulbe check the location of the donut sticker on the primary of a stock Lightbridge. I found couple of my friends own the Lightbridge have the problem where the donut was not placed exactly on the center by the factory. My Lightbridge was off 1.5mm. I hope Meade has corrected this.

[jhmvangastel]

I think this laser will be a very good tool to collimate the secondary, or, stated otherwise: to aim the axis of the eyepiece at the center of the primary mirror. But for collimating the primary a laser is only good when the laser spot does hit the center of the primary *exactly*. If not: you will introduce coma. A good cheshire doesn't need crosshairs. I am 61 and can use a cheshire perfectly well in the dark.

[HoTechUSA]

You are absolutly correct that the laser has to hit the center of the donut during the secondary mirror adjustment. I did the video in a rush, please forgive me for not emphasizing the issue. Special thanks for the reminder!

[franchu1]

Hi i ordered a SCA Laser Collimator Friday last after watching this video, very convincing i must say. Question, is the TELESCOPE IN THIS VIDEO A Meade LightBridge 8-Inch Truss-Tube Dobsonian ? I was wandering, i ordered one of those also,

[franchu1]

ok thank you. i will order one, i can see that it will work better than the stock provided.

[franchu1]

Hi i ordered a SCA Laser Collimator Friday last after watching this video, very convincing i must say. Question, is the TELESCOPE IN THIS VIDEO A Meade LightBridge 8-Inch Truss-Tube Dobsonian ? I was wandering, i ordered one of those also,

[HoTechUSA]

I am using a Meade LightBridge 10-inch Truss-Tube Dob on a 2" Crayford focuser. All parts are stock. Your 8-inch should work the same. And I would suggest to buy a Bob's Knob alignment screws for your secondary mirror. It will make your life easier while collimating it!

[kurtjmac]

Is it normal to have to put that much torque on the screwdriver while centering the secondary? I always scare myself when I'm doing that to my scope, I think I'm gonna bend the spider or crack the mirror.

[HoTechUSA]

Good question! I was not very confortable about doing it too, but I need that much force to actually make it move without loosen the entire secondary assembly. I have changed to Bob's Knob, and it works without making such scary torque on the spider anymore.

[n17babosh]

How much for one of these telescopes?

In £££ (GBP) please

[slupmed]

nice but i got a Cassegrain

[PilotoGretudo]

Thank you so much!

Great tutorial!

[Affje800]

Very helpful video, thanks