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Equipment Discussions >> Cats & Casses

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Kevdog
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Reged: 07/11/12

Loc: Desert Hills, AZ
HoTech SCT Laser Collimator?
      #5824056 - 04/26/13 10:38 AM

Just came across this.
http://www.optcorp.com/ht-act-m2-2inch-advanced-ct-laser-collimator-w-fine-ad...

As a relative newbie, I'm always wondering if my collimation is good or not. Was hoping this could either fix my collimation or at least assure me that I'm pretty close.

Anyone used the system and have comments about it?

I have a Carbon Fiber C11 (fork mounted) and would like to ensure I have good collimation!

Thanks


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Jim W. Coleman
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Reged: 03/04/13

Loc: Puget Sound, Washington, USA
Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5824122 - 04/26/13 11:02 AM

I have used this system to collimate my 12" Meade LX90 and it worked very very well. The main thing is to have patience and take your time. The OTA must be precisely aligned to the collimation plate, but they also provide slow motion fine tuning controls that make it pretty easy. I have been very impressed with the system - mainly because I live near Seattle and it's always cloudy or raining, so I can bring the scope in from the observatory and collimate it in my garage.

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Jim W. Coleman
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Reged: 03/04/13

Loc: Puget Sound, Washington, USA
Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5824135 - 04/26/13 11:10 AM

Here's a link to a pictorial I put up on how to use the Hotech Laser Collimator ... hope this helps (and hope the link comes through ... still new here and haven't figured everything out yet ...

http://www.colemanapps.com/Wordpress/tna/?cat=46


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ubermick
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Reged: 04/12/12

Loc: San Rafael, CA
Re: HoTech SCT Laser Collimator? new [Re: Jim W. Coleman]
      #5824641 - 04/26/13 03:13 PM

I haven't collimated mine (but really bloody should get around to it!) but this seems like a bit overkill when from what I've repeatedly read, a star does the job nicely?

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Kevdog
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Reged: 07/11/12

Loc: Desert Hills, AZ
Re: HoTech SCT Laser Collimator? new [Re: ubermick]
      #5825015 - 04/26/13 06:21 PM

I think it's all about confidence. I've read 5437 articles about collimating an SCT, but that doesn't mean I'm confident I'm "getting it right" when I actually go to do it. When I first got my C11, the "donut" when it is far out of focus wasn't even centered, so I'm definitely better than that!

$400 is a bit steep for sure, and it'd be easier to swallow if it was $200 or so.

I'm still not sure about getting one, but I'm thinking a 2" diagonal and upgraded focuser would do me better. But it's hard to decide!


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ubermick
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Reged: 04/12/12

Loc: San Rafael, CA
Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5825598 - 04/27/13 01:59 AM

Apologies Kev, wasn't trying to infer anything - like I said, I've never even attempted to collimate my wee C8. But if I had $400 to spend, then I'd probably go for their standard little laser collimator (which used to be something like $60 on Amazon, but is unavailable now) and spend the rest on a feathertouch.

Agree with what you say though. Anytime I've tried looking up info on collimating an SCT, most threads seem to devolve into a "Why waste your money, just use a star" type dealie, but those comments are always from folks who've done it plenty of times and are completely comfortable with the process.


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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: HoTech SCT Laser Collimator? new [Re: ubermick]
      #5826292 - 04/27/13 01:11 PM

It is a nice piece of equipment, but the reason I have one is because I collimate numerous scopes for other people. For my own scopes I was simply using a star or an artificial star. The question becomes, is it worth the cost if you only use it once or very rarely? That is up to you. If you watch for a little while, you can find one used for closer to $300 usually.

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WesC
Carpal Tunnel
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Reged: 02/06/13

Loc: La Crescenta, CA
Re: HoTech SCT Laser Collimator? new [Re: EFT]
      #5826410 - 04/27/13 02:04 PM

You know, it would be kinda cool to have a collective ownership of one of these things in a local area. That way we could distribute the cost and since its rarely used we could just pas it around when we need it.

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Mitchell Duke
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Reged: 04/22/08

Loc: Georgia
Re: HoTech SCT Laser Collimator? new [Re: WesC]
      #5826422 - 04/27/13 02:12 PM

Yes but does it collimate as good as a high power in focus star?

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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

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Re: HoTech SCT Laser Collimator? new [Re: WesC]
      #5826423 - 04/27/13 02:12 PM

Quote:

You know, it would be kinda cool to have a collective ownership of one of these things in a local area. That way we could distribute the cost and since its rarely used we could just pas it around when we need it.




If you have a local club, they could get on and have a periodic collimation night for everyone to bring in their scopes.


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Kevdog
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Re: HoTech SCT Laser Collimator? new [Re: EFT]
      #5830783 - 04/29/13 05:41 PM

Will try and find a used one.... good idea!

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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5830793 - 04/29/13 05:46 PM

Quote:

Will try and find a used one.... good idea!




There has been one up on AstroMart recently for under $300!!


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Kevdog
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Loc: Desert Hills, AZ
Re: HoTech SCT Laser Collimator? new [Re: EFT]
      #5830873 - 04/29/13 06:27 PM

I just looked on astroMart and found an ad for one, but can't see the full ad (not a member).

Is that one still current at under $300?


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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5830923 - 04/29/13 07:04 PM

Yes. That is the one. It is listed for $285. Even if you pay the fee to join, $300 is a good price.

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Kevdog
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Loc: Desert Hills, AZ
Re: HoTech SCT Laser Collimator? new [Re: EFT]
      #5830950 - 04/29/13 07:25 PM

Now just have to scrape up another $300! The last $300 went on a new 2" diagonal and a new 2" eyepiece. Thanks for letting me know!

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Ed Wiley
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Reged: 05/18/05

Loc: Kansas, USA
Re: HoTech SCT Laser Collimator? new [Re: EFT]
      #5830956 - 04/29/13 07:30 PM

Haven't used one and don't feel I need one. If you learn to collimate using stars (artificial or real) you will not need anything extra. BTW: regular lasers, very useful for Newtonians, are not useful for SCTs IMO. For collimation see, for example:

http://legault.perso.sfr.fr/collim.html
http://www.astromart.com/articles/article.asp?article_id=548
http://skywatch.brainiac.com/collimation.pdf (Uncle Rod his self)

Ed


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Jim W. Coleman
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Reged: 03/04/13

Loc: Puget Sound, Washington, USA
Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5831041 - 04/29/13 08:25 PM

I am reading comments from some similar to: "Why use a collimation device when the best way to do it is a star?" I agree. But living near Seattle, I don't get many stars to collimate by and when I do, I would rather be using my telescope. I purchased the Hotech system and used it to collimate my scopes over the winter, in the comfort of my garage. The system worked very well. It was pricey, yes. But it worked and when the skies started to clear in Spring, I was able to take the telescope back out to the observatory, throw it on the wedge and it's ready to go. I can fine-tune on stars over the summer but come next winter, I can bring everything back in and take my time to do a precise collimation indoors. Not everyone's situation is the same. Just my two cents...

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Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: HoTech SCT Laser Collimator? new [Re: Jim W. Coleman]
      #5831193 - 04/29/13 10:00 PM

I am glad it works for you, Jim.

Ed


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Kevdog
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Reged: 07/11/12

Loc: Desert Hills, AZ
Re: HoTech SCT Laser Collimator? new [Re: Ed Wiley]
      #5831969 - 04/30/13 10:50 AM

Funny enough being in Arizona, I don't have the same problem with clouds, but I do have the problem of telescope time outside. And coming into summer the heat is starting to build up so we don't have a lot of thermal stability. When I bought my 8" SCT in June, I couldn't properly collimate it until October when it finally started cooling off. No, the views weren't great either, but when I did stay up until 3am for cooler skies, I wanted to be viewing, not collimating.

I think this will be a good investment for me, once I have the money!


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ur7x
professor emeritus


Reged: 01/08/12

Re: HoTech SCT Laser Collimator? new [Re: Jim W. Coleman]
      #5832382 - 04/30/13 01:47 PM

Quote:

I am reading comments from some similar to: "Why use a collimation device when the best way to do it is a star?" I agree. But living near Seattle, I don't get many stars to collimate by and when I do, I would rather be using my telescope. I purchased the Hotech system and used it to collimate my scopes over the winter, in the comfort of my garage. The system worked very well. It was pricey, yes. But it worked and when the skies started to clear in Spring, I was able to take the telescope back out to the observatory, throw it on the wedge and it's ready to go. I can fine-tune on stars over the summer but come next winter, I can bring everything back in and take my time to do a precise collimation indoors. Not everyone's situation is the same. Just my two cents...




Ever think about renting time on your collimator?

I'm in Seattle/Renton/Bellevue a couple of times a year... I'm not interested in spending a few hundred on more laser gear... But I might be interested in trading a case of beer for an hour or two on one of these gizmos...

Anyone consider creating a national registry of Collimator owners who will rent time with their set up?


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bilgebay
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Re: HoTech SCT Laser Collimator? new [Re: ur7x]
      #5832403 - 04/30/13 01:55 PM

Come on! This will kill David's business

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ur7x
professor emeritus


Reged: 01/08/12

Re: HoTech SCT Laser Collimator? new [Re: bilgebay]
      #5833307 - 04/30/13 10:08 PM

Maybe, but imagine if every SCT dealer bought one and offered a $20 collimation service... or imagine if every star club bought one on a similar "club" deal...

I'm much more likely to drop a few hundred on this gizmo if I actually could try before I could buy... If I collimate with this thing and it produces the best views of Jupiter my 925 has ever produced then I'm very likely to buy one for my garage.


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WesC
Carpal Tunnel
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Reged: 02/06/13

Loc: La Crescenta, CA
Re: HoTech SCT Laser Collimator? new [Re: ur7x]
      #5834571 - 05/01/13 02:46 PM

This thing is cool, but its really overpriced.

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JJK
Carpal Tunnel


Reged: 04/28/08

Re: HoTech SCT Laser Collimator? new [Re: WesC]
      #5834703 - 05/01/13 04:00 PM

Quote:

This thing is cool, but its really overpriced.




Given the cost of the scopes that could most benefit from the device, I agree. However, it's likely not worth building, marketing and shipping it at a far lower price point.


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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: HoTech SCT Laser Collimator? new [Re: WesC]
      #5835166 - 05/01/13 08:30 PM

Quote:

This thing is cool, but its really overpriced.



What should the price be?


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WesC
Carpal Tunnel
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Reged: 02/06/13

Loc: La Crescenta, CA
Re: HoTech SCT Laser Collimator? new [Re: Calypte]
      #5835208 - 05/01/13 08:53 PM

$300 seems a bit more reasonable to me.

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ur7x
professor emeritus


Reged: 01/08/12

Re: HoTech SCT Laser Collimator? new [Re: Calypte]
      #5835265 - 05/01/13 09:25 PM

Given that some (many, most even) can (and do) collimate SCT's with a faint star basically for free...

Or with an artificial star that ranges in price from next to nothing to $25 for a really fancy LED flashlight with laser cut tiny holes...

They are basically marketing this tool to people who either have lots and lots of SCTs (like a dealer or a club) or to people who have such extreme weather conditions that they need every second under a clear sky... Or people with lots and lots of cash and nothing better to spend it on...

That and given the most people recommend collimation with the scope strait up (to minimize mirror flop) and this tool collimates with the scope "level"

If was $100 new I might consider it... at $500 new $300+ used... it is way down on my gear "want" list.

Still as I said... If I could try it out and see how my scope works with a horizontal laser collimation, and if it took my scope from "very very good" to "freaking amazing" then I would consider $500... Till then I will try for a clear night, a faint star and my 2X barlow.


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pk759
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Reged: 07/30/10

Loc: Below Rigel
Re: HoTech SCT Laser Collimator? new [Re: ur7x]
      #5836715 - 05/02/13 04:45 PM

For me this was worth money. I had my SCT for 3 years and never collimated it. I was always afraid to collimate in the dark because I did not want to ruin anything.

I developed my collimation phobia when I had my first scope. A reflector. I know people say it gets easier, but for me it did not. It seemed like all I did was make things worse each time I tried. That was why I went for the SCT. Refractors are too much money for aperature and at least the SCT held collimation better.

Was the Hotech expensive? Yes. Was there a learning curve? Yes, but not as steep as collimating a reflector. For me at least. I no longer panic when it comes time to collimate


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rmollise
Postmaster
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Reged: 07/06/07

Re: HoTech SCT Laser Collimator? new [Re: ur7x]
      #5836809 - 05/02/13 05:33 PM

Quote:


That and given the most people recommend collimation with the scope strait up...




No they don't, and it's not necessary. You must run with quite a different crowd, cause I ain't NEVER seen anybody do that.


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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: HoTech SCT Laser Collimator? new [Re: WesC]
      #5837415 - 05/02/13 10:55 PM

Quote:

$300 seems a bit more reasonable to me.



How much do you think it cost to design this thing, test it with probable engineering changes, manufacture it in China or Taiwan, ship it to the U.S., and sell it both directly and through dealers (e.g. OPT), allowing a profit for each? Do you think this can be done for a retail price of $300?


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ur7x
professor emeritus


Reged: 01/08/12

Re: HoTech SCT Laser Collimator? new [Re: rmollise]
      #5838248 - 05/03/13 12:16 PM

I've seen lots sites recommend using Polaris to collimate since it is more up than down. I've also seen "experts" recommend that for the best of Jupiter (for example) you are to line up with Jupiter, and then collimate on the closest star and then back to the gas giant...

Truth be told, I've collimated my scope flat, up, angled.. whatever... never had much of challenge with this... And never noticed any difference.

That too is another reason why I look at this with one eyebrow up... I collimated my old school Newtonian the old school way.. was never all that sure how close I was... Had nice round stars with the expected 4 Newtonian spikes... got a $30 laser gizmo for Christmas... stuck it in and what do you know... it was pretty much bang on.

I would hate to spend $500 only to discover that my free "faint star" effort or my (way over priced) $25 fancy shmancy laser cut holes LED flash light, which BTW looks very much like the kind they sell for $2, (or give away) at Harbor Freight... Is already bang on...

Again in my opinion, this should be offered as a walk-in service at telescope dealers... for something like $20... Like a quicky oil change... That's how both the manufacture and the dealers can make money with this thing...

And yes you can add me to the list of people who are nervous about having a Philips head screwdriver take a divot out of the corrector plate, but I have never had issue with a freebee LED flash light in the left hand and a stubby Philips in the right... It is a terrible design, Allen headed screws would have been better... Still I haven't sprung for a set of bobs knobs either.


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ur7x
professor emeritus


Reged: 01/08/12

Re: HoTech SCT Laser Collimator? new [Re: Calypte]
      #5838291 - 05/03/13 12:37 PM

Yes, given the cost to manufacture things in China it is probably profitable at even $100 per...

When the Newtonian lasers first came out they were very cost prohibitive. Most were well over $150 (many still are) and yet you can buy an Antares (or other Chinese made Newt collimator laser) for around $50, some are around $30. Funny how they all kinda look and work the same... You know like just maybe they are all built in the same factory and you are paying for the "manufactures" logo...

There is typically lots of profit built into "luxury" or "hobby" products.

It all depends on how many you can sell..

What is a fair price for this thing... I guess if people are willing to buy it at $500 new, then that's a fair price... Me, I would rather put that $500 toward a new Canon DSLR.

Oh and Agena and OPT have it on sale for $400... so yes it is likely very profitable at $300 given that the $400 price include free shipping to your door (at least at Agena it does).


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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: HoTech SCT Laser Collimator? new [Re: ur7x]
      #5838324 - 05/03/13 12:49 PM

Quote:

Yes, given the cost to manufacture things in China it is probably profitable at even $100 per...etc.



I'm sure David Ho would be happy to have you on his team, since you clearly know more about his business than he does.


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: HoTech SCT Laser Collimator? new [Re: ur7x]
      #5838397 - 05/03/13 01:26 PM

Quote:

There is typically lots of profit built into "luxury" or "hobby" products.




I would say that on average that is not true in this hobby, particularly when it comes to high quality products produced by small companies. Retail profits in this business are small and manufacturing generally just makes enough to get by. Most people making products can't even consider the R&D time or their hourly time in production if they want to feel like they make a profit at all. Having something manufactured in China requires huge volumes to ever be practical. Adding dealers only reduces profit in hopes of increasing sales to make up the difference. Many people in this business can only rely on it as a side line to their regular job or their spouse's job since there is simply not enough profit. I've seen at least three very high quality manufacturers shut down recently and that says a lot.

Many products have to be priced at what they will bring without regard to what they might actually cost to produce. That might make you ask "why bother?" but we do it because we enjoy it and because of the satisfaction in making a good product that people appreciate. Everybody wants it high quality but cheap. It would be great if we could all make a fortune in this business, but I don't know of anyone who does. I doubt that David is getting rich of any of his products, but they are well though out and very well made.


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ur7x
professor emeritus


Reged: 01/08/12

Re: HoTech SCT Laser Collimator? new [Re: Calypte]
      #5838418 - 05/03/13 01:41 PM

Sure whatever, lets just ignore that they have come down over $100 in price in the last 2 years. So Agena is selling them at a loss now?

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Kevdog
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Reged: 07/11/12

Loc: Desert Hills, AZ
Re: HoTech SCT Laser Collimator? new [Re: ur7x]
      #5843676 - 05/06/13 02:03 PM

Quote:

They are basically marketing this tool to people who either have lots and lots of SCTs (like a dealer or a club) or to people who have such extreme weather conditions that they need every second under a clear sky... Or people with lots and lots of cash and nothing better to spend it on...

That and given the most people recommend collimation with the scope strait up (to minimize mirror flop) and this tool collimates with the scope "level"

If was $100 new I might consider it... at $500 new $300+ used... it is way down on my gear "want" list.

Still as I said... If I could try it out and see how my scope works with a horizontal laser collimation, and if it took my scope from "very very good" to "freaking amazing" then I would consider $500... Till then I will try for a clear night, a faint star and my 2X barlow.




Or they are marketing it to people who haven't done an SCT collimation and aren't sure they "have it right". So on my $3000 C11, spending $400 to make sure I "have it right" isn't such a bad thing. Sure after I've done it a few times, I may be confident I had it right in the first place and then I might sell it along to another newbie.

You can collimate with the tool at 30 deg or so to keep the mirror in about the right place for much of your viewing. Just the first time it's recommended to do it level to reduce the variables for lining up the tool.

I'll probably look for a used one at around $300 and consider it money well spent. And if I later sell it for $250, then I just spent $50 to learn how to collimate my scope by myself. Not a bad deal.


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WesC
Carpal Tunnel
*****

Reged: 02/06/13

Loc: La Crescenta, CA
Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5843849 - 05/06/13 03:43 PM

I don't think products are marked up because this is a "hobby." I think products are marked up (or down) in order to balance between cost, profit and sales volume.

Astronomy, and even more so astrophotography, is a niche market. In order to make any kind of profit you either have to sell at a higher price or sell a LOT of product. Its about balancing that with cost. And there can be other reasons for products to be priced higher that have nothing to do with quality or value. Things such as the ability of a retailers to buy in enough volume to drive down their wholesale costs, the ability to negotiate good contracts for manufacturing component suppliers, the success of a manufacturer in accurately forecasting demand and producing the correct amount of product, etc...

There are reasonably-priced products, there are expensive products of high value and then there are products that are overpriced for their value, regardless of what they actually cost to design and manufacture. Sometimes its just a bad business decision to produce something that, while cool, costs too much to manufacture than its value in the market can sustain. Sometimes its just plain old greed.

In the end the market will determine if a product will survive, or will eventually balance its price/value point. The fact that this collimation tool has dropped in price by $100 indicates to me that the manufacturer may not be selling enough of these at $500 and is adjusting the price to see if that will improve sales over the long term.

At $500+ I personally don't feel that this product's value is in balance with its price. Its value to me feels more like $300. To someone else it may be less or more. If the manufacturer finds the sweet spot for this product, then sales will improve. There will always be a segment of the market that doesn't find the price right for them, no matter what it is.

C'est la vie!


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Kevdog
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Reged: 07/11/12

Loc: Desert Hills, AZ
Re: HoTech SCT Laser Collimator? new [Re: WesC]
      #5843897 - 05/06/13 04:12 PM

Early adopters always pay some of the development costs. Yes, to me $300 seems the sweet spot, but he had to recoup some of the development and tooling costs, which I imagine is why it is still $400 retail.

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Christopher Erickson
Carpal Tunnel
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Reged: 05/08/06

Loc: Waikoloa Village, Hawaii
Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5844955 - 05/07/13 06:08 AM

Knowing that David Ho is a guy who really cares about his customers, I doubt that it is priced one dollar higher than it has to be to keep it as a viable product on the market.

And another point to consider. If it really was overpriced for what it is, David's arch-competitors would come up with a cheap Chinese clone of it and try to undercut his market.

And all of my HotechUSA products say "Made in USA" on them.

I hope this helps.


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rmollise
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Re: HoTech SCT Laser Collimator? new [Re: Christopher Erickson]
      #5845087 - 05/07/13 08:26 AM

Quote:

Knowing that David Ho is a guy who really cares about his customers, I doubt that it is priced one dollar higher than it has to be to keep it as a viable product on the market.

And another point to consider. If it really was overpriced for what it is, David's arch-competitors would come up with a cheap Chinese clone of it and try to undercut his market.

And all of my HotechUSA products say "Made in USA" on them.

I hope this helps.




Bingo. The collimator is also _very_ well made.


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Calypte
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Re: HoTech SCT Laser Collimator? new [Re: rmollise]
      #5846292 - 05/07/13 06:25 PM

Quote:

And all of my HotechUSA products say "Made in USA" on them.



My Astro Aimer G3 only states the manufacturer and his address, not where the product was actually made. We use them at Palomar Observatory to point out things during tours. That aside, there's always a simple solution if you think an astro product is too expensive: don't buy it! If enough people say "no," then the product's price will either come down or (more likely) the product will disappear. That'll show 'em! A few years ago I contacted the manufacturer of a line of eyepieces that I liked that were no longer made. I had this crazy idea that maybe with a little bit of money I could get him to start making them again, and I (thinking modestly) could become the US sales rep, and I'd travel to all the shows and star parties while showing off these eyepieces, and I'd be eating in fancy restaurants with industry bigwigs and the editors of S&T and Astronomy. The guy I contacted told me he thought it would require about $250K to bring back the product. For one thing (if nothing else), there'd need to be a minimum order from the factory in Japan, so if I indeed had that kind of money (I didn't), I'd end up with thousands of these eyepieces sitting in my garage, waiting, hoping, that someday I'd recoup my $250K. There were originally four focal lengths. Inevitably some would be more popular than others, so I'd probably go to my grave with some of the less popular FLs. And meantime I'd be reading posts that they cost too much, and why didn't I come out with some other focal length, and somebody's going to say they'll never buy any from me because they think I'm a schmuck for how I talked to them at RTMC in 1995, etc., etc. Meanwhile, somebody'd be saying that Explore Scientific has eyepieces just as good for $50 less. For me it was a bit of a reality check on the business. A lot of my own money would be on the line, and there'd be absolutely no assurance I'd ever get it back. The claim of "overpriced" for some of this stuff acquired new meaning.


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Re: HoTech SCT Laser Collimator? new [Re: rmollise]
      #5846511 - 05/07/13 08:14 PM

Quote:

Quote:

Knowing that David Ho is a guy who really cares about his customers, I doubt that it is priced one dollar higher than it has to be to keep it as a viable product on the market.

And another point to consider. If it really was overpriced for what it is, David's arch-competitors would come up with a cheap Chinese clone of it and try to undercut his market.

And all of my HotechUSA products say "Made in USA" on them.

I hope this helps.




Bingo. The collimator is also _very_ well made.




I agree. I'm tempted to get it to help collimate a Meade/Wegat 125 Mak-Cass, which only cost me about $450 used. Collimating that scope under the stars would be an exercise in frustration. Access the primary mirror lock/alignment screws requires taking off the visual adapter and the protective cover, adjusting the screws, putting the cover and visual adapter back on, add an eyepiece, and then rinse, lather, and repeat over and over again. The Hotech tool avoids the need to use an EP to collimate the primary and center the optical train.


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gaz-in
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Re: HoTech SCT Laser Collimator? new [Re: JJK]
      #5847340 - 05/08/13 08:57 AM

Got one...really like it...I have learned lots about how my sct operates by fooling aroung with it....chated with the designer at NEAF. Like so many in this hobby, a real great guy!

So glad we have him designing and making tis type of product available....


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Wade Van Arsdale
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Re: HoTech SCT Laser Collimator? new [Re: gaz-in]
      #5847691 - 05/08/13 12:39 PM

One of the best uses I've found for David Ho's Advanced CT Laser Collimator Kit is to check centering of the secondary mirror to the primary mirror's optical axis. It's the best tool I have for checking centering on the Planewave CDK scope also, not just SCT's.

David has a neat trick he uses of putting a piece of Scotch Magic Tape (translucent) over the center laser hole on the kit's faceplate (the large white square plate with the hashmark and circular grid stamped into it that catches the return beams from the laser).

This piece of tape diffuses the laser beam to a spread-out, large donut pattern that you use to check the secondary centering. On scopes such as the EdgeHD, centering of the secondary gets much easier since those models have 4 adjustment screws along the front collar.

While some designs like SCT's aren't particularly sensitive to decentering error, every little bit of precision alignment that you can get helps on performance, especially at the edges of the field on large-chip cameras used at long focal lengths and severe image scales for deep-sky imaging. This becomes especially true if the scope was way off-centered like some I've seen.

So far, I've used David's kit to diagnose and fix three decentered SCT's, one of which was badly decentered, and also diagnose a mis-machined focuser on the back end of a Dall-Kirkham that was tilted from the optical axis and couldn't be fixed without a replacement.

For me, the kit has been a great diagnostic tool for the *other* alignment problems of the scope besides collimation (although as said here already, if you take the time required to "landmark" the lasers properly on the OTA, it will do a very good rough-collimation for you).

I still find my best *final* collimation tool is a fast webcam to freeze the atmospheric seeing (star swim), and a real star near zenith for least atmospheric interference...but only after I've worked the scope over with the Hotech kit first.

As has also been said here already, the Hotech is a great learning tool too, so you can understand better all the alignment variables for your scope.

So many times an SCT or other compound mirror scope gets talked bad about for not performing when in reality it is just mis-aligned all the way from focuser to front glass, in ways *other* than just basic collimation. That's where the Hotech really comes into play the best, IMO.

Wade


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HowardK
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Re: HoTech SCT Laser Collimator? new [Re: Wade Van Arsdale]
      #5847736 - 05/08/13 01:05 PM

Wade

I still use Metaguide and my Mallincam on my Planewave 12.5 and my new 8" Edge.......its a great help in collimation to be sure

I remember your help


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Re: HoTech SCT Laser Collimator? new [Re: Wade Van Arsdale]
      #5848010 - 05/08/13 03:23 PM

Quote:

This piece of tape diffuses the laser beam to a spread-out, large donut pattern that you use to check the secondary centering.



This does not sound right to me. According to the user’s manual, the large donut pattern is used to square (align) the collimator with the OTA. I would think that a single test like that can’t be used to adjust reliably two different things! If the donut pattern is off, then you don’t know whether it is because of the secondary or the OTA misalignment.


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gaz-in
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Re: HoTech SCT Laser Collimator? new [Re: Alph]
      #5848471 - 05/08/13 06:53 PM

I think where folks are missing is this is so much more than just a collimation device.

As was mentioned, centering the secondary. David chatted with me at NEAF about how to check/fix this. I came home and found my secondary to be in need of centering. Using the Hotech tool I was able to adjust to much closer to center...

As far as diagnosing things, it helped me realize that I had a diagonal where the mirror was not at the correct angle...rotating the diagonal showed the diagonal mirror was not squared properly to the light path. Swapping diagonals really helped the view....


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Wade Van Arsdale
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Re: HoTech SCT Laser Collimator? new [Re: Alph]
      #5849888 - 05/09/13 11:55 AM

Alph,
What I'm talking about re. centering the secondary to the primary probably isn't in the user's manual (haven't looked at his latest manual). I got the information about this directly from David Ho via phone and email.

David probably doesn't include this step in the manual because it is pretty uncommon on an SCT to have one so badly decentered that it makes a difference (although on one of my three SCT's I've worked over with this kit, it WAS badly decentered enough that it showed up in Roddier tests pretty clearly). And on a warrantied scope, you could mess up your warranty on an EdgeHD OTA if you touch the front collar adjustment screws...see disclaimer below!!

What you are talking about in the user manual is the *initial* part of the co-alignment of laser (white face plate of laser kit that sits in front of the scope) to *primary* mirror, not secondary. This is the "laser landmarking" procedure I mentioned earlier.

For this initial step, you use only the *outer* edge of the donut pattern and shift the white laser face plate and its printed grid to the donut. You're not adjusting anything on the OTA at this point, only the laser face plate in front of the scope.

But in the secondary mirror centering step, *after* you have the laser landmarked properly to the primary mirror and optical tube wall, you use the *inner* dark portion of the donut pattern with the diffuser tape in place and instead of adjusting the laser plate's positioning, you adjust the corrector's lateral positioning on the OTA until your center dark hole is orthogonal to the grid marks on the laser face plate. (Note, this is darn near impossible to get right unless you have a spider vane with adjustment screws or the newer Celestron OTA's with corrector adjustment screws around the front collar of the scope).

***IMPORTANT: to anyone reading this, you might void your warranty on an EdgeHD tube if you try to start aligning the corrector using the four front collar screws!!!! You do this at your own risk. If in doubt about what to do, check with Celestron *FIRST* before proceeding.

Also keep in mind, for SCT's, your secondary centering has to be WAY out of whack to make a difference in overall optical performance. So if you think it's close to within a couple of mm laterally, let it be!!

The center dark hole of the pattern in this step is just a "shine-through" of the secondary coming from the primary mirror only, not a laser bounce off the secondary. You're just sillouetting the secondary against the laser plate and using its shadow on the pattern projected onto the laser plate.

(Note, It's been awhile since I've conversed with them, but last I heard from them, Planewave uses this same kit and same procedure for centering their secondaries at the shop while assembling according to Allen Keller. They may still be doing it this way for all I know).

I hope this makes more sense now. It's very difficult to visualize just by reading when you don't have the kit and scope in front of you doing it, esp. for undocumented steps like this. But it really does work. The laser kit has several modes of laser beam shooting and you use different modes depending on what part of the steps you are on.

For final checks of back-end and focuser squareness and orthogonality, after you've done everything else, *then* you start using the return beam coming from the secondary mirror to the back end of the scope and out the focuser. But I like to collimate on a live star first before going to the back-end checks. This helps rule out everything from the primary mirror forward and isolate *just* the back-end and focuser.

This is also where you can check for mis-machined, out-of-square/sagging focuser or back-plate tilt.

I think of it as a systematic alignment from front to back, in this order:
1) Co-align laser face plate to primary mirror.
2) Align secondary to primary mirror--**CHECK-ONLY** just to verify when it's an SCT. Leave it alone if close!!!
3) Collimate on live star, using a fast webcam on star near zenith for best possible results.
4) Check back-end return beam from secondary (*after* collimation on a live star) for backplate tilt and focuser sag/tilt, mis-machined and not square to optical axis.

Note: focuser checks on SCT scopes only if using an aftermarket focuser (Crayford, etc...).



*STOP HERE UNLESS YOU'RE INTERESTED IN THE BACK-END TESTS*

*After* you have a verified precise collimation on a live star (I use a fast webcam and star near zenith for this to see the best possible diffraction ring pattern), to do the back-end tests, you do this:

1) If using an aftermarket focuser instead of factory knob, rack focuser in and outside of focal plane to see if the return beam from the secondary mirror coming down the baffle tube stays within a couple mm of the same spot on the kit's rear "eyepiece" reflector that you insert into the focuser drawtube. Remember, this a greatly magnified beam at the back-end, so 1-2mm of variation is OK for many scopes. You have a problem if the impact point of the beam swings several mm back and forth as you rack or rotate on the back. This may indicate drawtube sagging or focuser body to drawtube alignment is not square. (Note, this step is difficult because as you rack the drawtube, the impact point of the laser will enlarge and go out of focus. So just check the outer edge of the defocused beam both in and outside focus and see if its donut pattern stays roughly in the same place for its impact point).

2) If the focuser has a rotation feature built into it, rotate the focuser without moving the drawtube while *at* focus, then lock it back down. Do incremental 90 degree rotation stops and check after each one. See if the laser impact point stays square on the back end. If not, indicates slop in the rotation mechanism or off-square machining of focuser or adapter plate of focuser.

3) If possible, rotate the *entire* backplate assembly without touching the focuser and with the focuser rotation locked in place and the drawtube at the focused position (you can do this on Planewave scopes and some other brands). Same deal there...watch for laser impact point large swings.

This gives you a systematic approach to checking back-end machining squareness and orthogonality.

That's the value of this kit. It's NOT just a collimator even though it's sold primarily under that flag. I would call it more of an "aligner and collimator" kit.

Hope this clarifies,
Wade


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Kevdog
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Re: HoTech SCT Laser Collimator? new [Re: Wade Van Arsdale]
      #5849990 - 05/09/13 12:53 PM

After spending 30 mins or so fiddling with the collimation last night and probably ending up worse than when I started, I know I'm saving my pennies to buy one of these.

Saturn is downright fuzzy, so I know I'm off somewhere and was trying to tweak it last night but I just can't quite recognize which way to go, no matter how many articles I've read. What I see in my eyepiece does not look like the pictures I see in the collimation articles no matter what I do. I'm sure I'm missing something simple, but for now I don't know what.

It'll be worth $400 and 1hr to "get it right" and then be able to fix it again later if I need to!


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mega256
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Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5850096 - 05/09/13 02:04 PM

After buying a C14 and a C11-HD over the last 12 months,(7K)
This is money well spent.(IMHO)...
Yes star adjustments are good, but sometimes difficult to do
in unstable air.....most of the time its best guess....
(my practical experience)...
I was very lucky to find a used one and look forward to
using this device...Also for centering the corrector plate
will be a great help.(they are now adjustable with set screws).
I find that my artificial star just has to be too far for me to use.......
I have a C6 and AT6RC to try also,but I understand the min scope dia is about 7",but I plan to try it on them also..



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gaz-in
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Re: HoTech SCT Laser Collimator? new [Re: mega256]
      #5851439 - 05/10/13 06:50 AM

When I chatted with David he gave slightly different means to center the secondary. Once all set up and the the HOtech reflector is placed in the read of the SCT you will see three laser dots on the Hotech reflector installed in the rear cell.

1) adjust the focus so the three dots on the rear reflector converge.

2) if the converged laser dots are not centered on the reflector target (not the big target on the tripod, the one installed in the rear cell of the SCT), the secondary is not centered.

3) Loosen the outer screws on the corrector plate and slightly move the corrector plate and secondary assemble to get the converged dots near the center of the target on the reflector.

Edited by gaz-in (05/10/13 06:53 AM)


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gaz-in
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Re: HoTech SCT Laser Collimator? new [Re: gaz-in]
      #5851445 - 05/10/13 06:58 AM

"you adjust the corrector's lateral positioning on the OTA until your center dark hole is orthogonal to the grid marks on the laser face plate."

could explain a little more about what you mean by "orthogonal to the grid marks" I interpret "orthogonal" as meaning at right angles or perpendicular...is that correct?

Thanks tons..


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Wade Van Arsdale
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Re: HoTech SCT Laser Collimator? new [Re: gaz-in]
      #5851670 - 05/10/13 09:59 AM

Lateral (side-to-side/up-down) only, not "tip-tilt".

"Concentric" would have probably been a better word to use there.

Wade


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Wade Van Arsdale
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Re: HoTech SCT Laser Collimator? new [Re: gaz-in]
      #5851748 - 05/10/13 10:44 AM

Gaz-In,
This way will likely be more accurate, but might also be a little harder to achieve because it introduces secondary mirror tip/tilt (collimation errors) into the mix along with possible decentering error at the same time.

Using the front shadow as an initial step after co-alignment eliminates that potential problem because you're not using the secondary mirror to reflect the beam to the back end (yet).

I use anything from steel tape to digital calipers on the front plate and its grid marks to measure the secondary centering. But I think the procedure you listed would work great as a final check after the "shadow test" up front, then collimation on a live star or with the Hotech.

Often, when you start using the secondary bounce at the rear, final alignment out the back end turns into an iterative process (too many moving parts at same time as Alph mentioned earlier). But I definitely use the secondary bounce out the back end as the final part of the process after the other alignment steps are complete.

In a pinch if your skies are too bad for live collimation, the laser kit's collimation simulation will still get it pretty close....enough to do all the back-end steps you and I mentioned.

Best,
Wade


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Kevdog
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Re: HoTech SCT Laser Collimator? new [Re: Wade Van Arsdale]
      #5852528 - 05/10/13 06:56 PM

Order made. Should have my impression of the kit and pics next week hopefully!

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gaz-in
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Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5852659 - 05/10/13 08:03 PM

I found that when I rotated my diagonal in the rear cell the pattern on the reflector eyepiece moved around. I assume this means the diagonal mirror is not aligned properly?

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Wade Van Arsdale
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Re: HoTech SCT Laser Collimator? new [Re: gaz-in]
      #5853701 - 05/11/13 12:19 PM

Gaz-in,
If this was on an SCT with an aftermarket focuser, and nothing else on the back-end was moved any (or factory knob turned any) during diagonal rotations, the diagonal would be a likely cause: either mirror misaligned internally in diagonal, or diagonal body not machined square or has slop in its fit into the drawtube.

**But** one caution on reading too much into the movement:
You should expect a small tolerance zone even if the diagonal was the only thing that got moved during the test, especially if the diag. is a clamping-style, not rigid screw-in.

If the error is larger than a couple of mm, compare it to a different diagonal if possible, to see if both do it (keeping in mind they could *both* be bad).

To keep things as simple as possible, I like to do all the Hotech collimation steps and a live webcam star test *without* the diagonal first, then add the diag. back in at the very last.

If the errors are very small during the diagonal rotation test, it is unlikely they will show up in visual or camera use with the diagonal. Verify this with a live webcam collimation test if possible.

Do you have another diagonal or two you could try just to compare (or borrow a buddy's)? This might help zero in on the cause.

Hope this helps,
Wade


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Hamsterdam
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Re: HoTech SCT Laser Collimator? new [Re: Wade Van Arsdale]
      #5854466 - 05/11/13 10:02 PM

For 1.5 years I have had an efficient, and free collimation system....a 10" SCT that wouldn't focus. 2 times in the field looking at bright donuts with a perfectly centered black hole for hours, trying spacers, etc, to achieve focus. The guy that lead me to the solution told me, "well, at least you know you don't need to collimate!" Then, as silly as it sounds, I super tightened the set screws on the focus knob, and now I can see stars, rather than donuts. Had the mirror not shown full throw when tested at home, this could have been diagnosed the first time, but it gave me variable symptoms. Ultimately it was use, a brass ferrule w/steel set screws to chew through the ferrule, then it would work indoors because of warmth, and dry air. When in the field, I suspect that humidity (slippage) and cool air causing metal contraction were the deceivers in my mind bending mystery. No matter how embarrassing a solution is, if it is free, and solves the problem... Please —embarrass me to death with my other malfunctioning machines!

One, mostly on topic question to add. If one were to switch to Bob's Knobs, you would expect to have to re-collimate immediately, no?


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Wade Van Arsdale
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Re: HoTech SCT Laser Collimator? new [Re: Hamsterdam]
      #5854585 - 05/11/13 11:18 PM

Quote:


......If one were to switch to Bob's Knobs, you would expect to have to re-collimate immediately, no?




Yes, it's very likely you'd need to re-collimate after a changout of collimation screws/knobs.

Wade


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mega256
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Re: HoTech SCT Laser Collimator? new [Re: Wade Van Arsdale]
      #5857205 - 05/13/13 10:58 AM

WoW just got mine,and what a well made device and a great
soft case to store it in...A very nice pro product !
Im happy,now the fun begins...lol...


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mega256
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Re: HoTech SCT Laser Collimator? new [Re: mega256]
      #5859480 - 05/14/13 09:55 AM

After a 4 hour learning session...Cool got it..
And it WORKs!..Checked it out on Saturn and some stars...my adjustment was right on..
From what I understand there are 3 versions of the manual...
Ver 5,8 and new 9.
Mine came with both types of 2" mirror's...normal and a new one that is transparent,with a crosshair rectical that shows the laser dots behind the EP mirror.
Its now much easyer to use in setups,no need to find the screws at 90deg..
And by removing the secondary in my new C11HD I could check the total optical path,including my jmi focuser first,looking at the cross at the EP and over laping the hole reflection in the round screen,,,it was fast setup!
My confedence level is now very good!
I did not want to touch my new HD scope,until I could spend
the proper amount of time to set it up..
I now have no worries about removing secondary ,for fastar,
and cleaning corrector plates on my cats..
So for the price of a good EP,this is justified.

http://www.hotechusa.com/2-Reflector-Mirror-p/rm2.htm

Edited by mega256 (05/14/13 09:59 AM)


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Ed Wiley
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Re: HoTech SCT Laser Collimator? new [Re: mega256]
      #5859773 - 05/14/13 12:21 PM

At the TSP two observing buddies who are expert collimators assisted me in collimating my C11 Edge using Arcturus. No tools, only the star and Bob's knobs. I learned a lot. Result: spot on collimation and resolution under the Dawes Limit as confirmed by a resolution target.

Ed


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mega256
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Re: HoTech SCT Laser Collimator? new [Re: Ed Wiley]
      #5860118 - 05/14/13 02:44 PM

Yes I agree with you..and a good night with stable
skys and temp right does a good job.But I seldom
have those in SW florida.Now I don't have to spend time
at night.I was able to center the total optic system,including the corrector and my JMI electric focuser
in my living room.
BTY after centering the lasers,by removing the secondary
and using the new 2"crosshair mirror ep.I was able to center all 3 retun beams on target(only had 2 b4)and found
that all 3 screws had to be redone to move to the center line.Now inter and outer focus on a star is the same ,with almost no focus or image shift..This was on a brand new C11edge.Sending it back to celestron was not an option for me as shipping cost and shipping back may have done the same. My problem (I think) was that the screws were lose to start with? Last night was not clear but Saturn was the same and did not shift with inter/outer focus.
I will have to give celestron an ata boy in design that removing and repacin the seconday had no effect on alignment.
By the way....this device does not work(as advertised) on a 6" scope,both my C6 ant AT6rc are too small to get the 3
laser beams through that diameter..must be over 7" to work.


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Re: HoTech SCT Laser Collimator? new [Re: mega256]
      #5862684 - 05/15/13 05:27 PM

Unit arrived today. As others have said, very very well built!

The kit has changed since the original. No longer do you need to put the tabs on the back of the celestron telescope with the strap! Whee! That was the part I was dreading the most. Now David uses diffraction tape over the crosshairs to form a donut to center the telescope's primary mirror. But it looks like it went even one step further as it appears that the reflector has it built in now? I got (a dim) donut back without the diffusion tape. If I blocked the sunlight through the window then I could easily see it. (And that's AZ sun). Putting the diffusion tape on showed the same (but brighter) donut so it was good for aligning it.

After aligning the donut with the target, I then aligned the crosshairs back on the target with the fine adjustment stage knobs. Once that was done I switched to laser dot mode (mode 2) and looked for the dots. I saw one way off to the side and no others. As I thought, my collimation was way off. Even though the highly OOF donut through the eyepiece had been centered, my secondary was still quite far off.

When I looked back at the reflector in my diagonal, I saw a single laser dot off to the very edge of the target. So I started adjusting the secondary until I got the dots near the center of the target in the reflector. Then they appeared on the main target.

Spent several times fiddling with the collimation, then double checking the alignment of the scope and target and then double checking the collimation again.

After reading the manual and all the threads on how to do it several times, plus watching the youtube videos, it only took me 30 mins to complete the procedure. The new "donut" alignment made that process much quicker! I'm glad I paid for a new one with the upgrades. It was worth the extra $$$.

I doubt it is perfect yet, but I'm sure it's much much better than it was. Hopefully I can get out tonight and try Saturn. Will follow up when I've had a chance to get it under the stars. But so far 5 star recommendation!


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Kevdog
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Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5874153 - 05/20/13 04:23 PM

So had another go as the first time I didn't take enough time doing the alignment of the scope and the collimator. Did it much more carefully this time and I think I have it. Have to star test again sometime this week. Also kept rechecking the centering to be sure nothing moved.

Here's my final alignment. Hard to see with the cell phone camera. Forgot to bring my good camera


Saw the 3 dots do converge on the reflecting eyepiece off center. I'm guessing this means my secondary isn't quite centered? Rotating the eyepiece didn't change it, neither did rotating the diagonal.


Edited by Kevdog (05/20/13 04:34 PM)


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Alph
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Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5874273 - 05/20/13 05:24 PM

Quote:

Saw the 3 dots do converge on the reflecting eyepiece off center. I'm guessing this means my secondary isn't quite centered? Rotating the eyepiece didn't change it, neither did rotating the diagonal.



You should not have used a diagonal. I think your are still off. The doughnut is not centered and the bottom laser return is off.


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Kevdog
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Re: HoTech SCT Laser Collimator? new [Re: Alph]
      #5874492 - 05/20/13 07:21 PM

My diagonal is an SCT diagonal. I can't remove it as it screws onto the 2" SCT threads in the back (no 2" visual back). Plus I use it for observing, so it better be collimated with it in.

I really should have had my better camera. The donut looked centered from what I saw.

What is still odd though is the top 2 lasers are oval in line with the axis of the center of the target. The bottom laser is oval is tangent to target circles, which makes it hard to verify that they are in fact on the same axis line! I wonder if that bottom laser needs rotated slightly?

I may set it up tomorrow again and bring my good camera for better pictures and try it again. See if the results again match.


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HOTECH
Vendor - Hotech


Reged: 10/23/08

Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5875154 - 05/21/13 05:10 AM

Hello Kevdog, Great setup!
1. Can you move the collimator closer toward the telescope so the inner tip of the crosshair lines expand to ring 1.5. This way, it is easier to identify if your secondary mirror is concentric to the primary optical axis.

2. The converged three dots on the reflector mirror's target:
Your mirror is properly positioned in the focal point because the three dots are converged into one. But they are not centered as you mentioned. Your guess is correct that most likely the secondary mirror is optically decentered if the co-alignment is properly done.

3. Before you begin any adjustment, I like to know what are the available adjustments you have and you can do on your scope.
a). Do you have tilt adjustment on the fouser? This can help you to square up the focal plane to the primary mirror's optical axis. You can shim the diagonal locking thread to achieve this.
b). Can you detach the secondary mirror assembly? Not a very hard task but you will need to pre-index the orientation of the assembly first. This adjustment will allow you center position your secondary mirror to the primary optical axis and help you to square up the focal plane to the primary mirror's optical axis.

Thanks for your posts, and I will do my best to walk you though.

Clear Skies!
David


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Kevdog
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Reged: 07/11/12

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Re: HoTech SCT Laser Collimator? new [Re: HOTECH]
      #5875588 - 05/21/13 11:20 AM

Thanks, you have a great tool. Very very well made.

1. Yes, I'll do it closer on the the next go around today. I'll take a picture once I have that set up. Still don't have the good camera with me, but I'll try and get a better picture.

2. I do have the removable secondary for the faststar system. I've read that unless it is highly decentered, don't mess with it. I'll do the alignment like you said in step 1 and see what it shows.

3. I have the Williams Optics 2" CF diagonal here:
http://agenaastro.com/william-optics-2-carbon-fiber-dielectric-star-mirror-di...

I am currently using it with the SCT adapter, then planned to get a crayford focuser later and switch it to refractor mode. So I currently only have the standard focusing mechanism on the C11.

a) No aftermarket focuser yet, so just the SCT diagonal directly connected to the 2" threads of the SCT back

b) It's a faststar system, so it easily unscrews. I'm guessing that the faststar system only screws on one way, so it's automatically "indexed" for me. Not sure if the faststar system has any adjustements built in for centering?

So I have the old carbon fiber tubed Fastar C11 with the WO CF diagonal. Everything else is stock.

Thanks for your help!


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mega256
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Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5875796 - 05/21/13 12:43 PM

Yes the fastar is keyed and goes back with no problems.I was surprised that my settings held very well when putting the secondary back in..

I found out that removing the secondary first and then center the lasers in the focal plane,was fast and gave me some insite on how things were lined up...(corrector,focuser,ect)

Then put the secondary back in and proceeded to do the rest.
Im looking forward to the new setup instuctions with the new crosshair mirror.
I will say a stable secure tripod to mount the laser ,makes it much simpler job to do.

BTW David told me how to check the device for alignment:

Turn and square to a flat wall and one of the beams should
be in line with the X pattern on the wall..The other 2 will
be off the X ,but in good spacing.

Edited by mega256 (05/21/13 12:50 PM)


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Kevdog
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Re: HoTech SCT Laser Collimator? new [Re: mega256]
      #5876287 - 05/21/13 04:19 PM

Okay, so had another go. I put the target closer at first just to see if the secondary is off center. It is, but not by much (1/2 a circle or less when the outer ring of the donut was on the 3)

I then moved it back again for another collimation run. Made sure to carefully center the crosshairs/donut and align the crosshairs to the target. Fixed the collimation (it was close).

Then I reset the target to a different location (higher and a bit farther away), so then I realigned, retargeted and the alignment was still right on, so I'm happy with that.

The dots in the eyepiece reflector are still a bit offcenter as in my previous picture, so that still matches with the secondary being offcenter.

Then also took the diagonal out and tried just holding the reflector against the 2" SCT opening on the back of the scope. Had to refocus, but then the collimation was still on.

The dots in the eyepiece reflector were still the same amount offcenter doing it this way, so I think my diagonal is fine.

Thanks for all the help. Now gotta get it under the stars again.


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HOTECH
Vendor - Hotech


Reged: 10/23/08

Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5876810 - 05/21/13 07:42 PM

Thanks Mega256! I would also like to touch up from your description in the following as well.

1. Kevdog needs to check if the focal plane at focal point is square to the primary optical axis first.
- Remove the secondary mirror assembly.
- Co-align the primary to the collimator crosshair by lining up the reflected crosshair back on the collimator target symmetrically. Make sure the outer tip of the crosshair lines are all on the same track, and the crosshair lines are also lined up to the target cross lines. At this point, your primary mirror is optically aligned to the collimator.
- Install the reflector mirror in the focuser. You can try both with and without the diagonal and see if the diagonal corresponds to the visualback focal plane.
- Observe the reflected crosshair from the reflector mirror and see if the crosshair laser is also reflecting back to the center of the collimator target. You should see two crosshair overlapping on the collimator target. One larger diameter (from the primary) and the other smaller from the reflector mirror/focal plane.
- If the small crosshair don't coincide on the target, your focal plane is off/tilted.
- If the crosshair exhibit behind the reflector mirror's target is not centered, your focal plane is decentered.
- Correct the tilt first by shimming the connection between the focuser and the visualback. Usually, I will use a third party focuser has tilt capability to square this up.
- The tilt can also came from mirror flop. You can adjust the primary mirror focus (in/out) and see if the primary mirror crosshair shifts. If you can control to make the change and line up both crosshair reflection. Lock down the primary focus after achieving this. And this will keep the whole scope optically and mechanically lined up from the primary optical axis to the focal plane/focuser.
- The next step will be optically centering the secondary mirror in the primary's optical center.

Before we start the secondary centering procedure, I would like to emphasize a few fundamental requirement on a good scope.
The whole scope should build around the "optical axis" of the primary mirror. Then the rest of the optical train elements will follow accordingly. Often time, the mass produced telescope makers assume that the mechanical axis is the same as the optical axis, then they slap the rest of the parts under mechanical alignment. A good scope maker will allow some room to shift around to correct the inherited tolerance (both optical and mechanical) discrepancy, but most will just glue the whole thing together without any feedback system. This is the trade off for "ready to use" scope. But the adjustments are far cry limited if the mfg. did not do it right on the first time. The scope is pretty much stuck on its performance without any possible optimization. Some people would say it is time for a 'better' scope. But in fact, if you can do some adjustment with the help of the collimator, you can revive the scope with your well spent effort in it.

This is where the hobby fun kicks in. We will find anyway to tweak each part to improve the ever ending optimization quest. A full collimation process can elevate your understanding of the instrument you use and built confidence in you with no fear of adjustment on each optical element. In the process, we learn, share, and enjoy the hobby.


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HOTECH
Vendor - Hotech


Reged: 10/23/08

Re: HoTech SCT Laser Collimator? new [Re: HOTECH]
      #5876911 - 05/21/13 08:53 PM

The following is the general guideline to the collimation procedure.

Co-alignment distance: Find a good distance that the central shadow cast by the secondary mirror is at least on one of the target ring between ring 1 and 2 as I've mentioned earlier.

1. Line up the focal plane to the primary mirror's optical axis.
- Remove the secondary mirror with the corrector plate.
- Co-align the primary optical axis to the collimator.
- Make sure the outer tip of the crosshair are symmetrical to the same ring on the collimator target.
- Make sure the crosshair are also lined up to the target printed crosshair.
- Install the reflector mirror in the focuser.
- Adjust the focuser tilt to center the reflected crosshair back on the center of the collimator target.
- Make sure both reflected crosshair (from the primary mirror and from the reflector mirror in the focuser) are all lined up to the printed cross on the collimator target.
- At this stage, your focal plane is guaranteed orthogonal to the primary optical axis.

2. Center the secondary mirror in the primary mirror's optical axis.
- Position the secondary and the corrector plate back on the scope. Do not lock it down yet.
- There will be some weight difference where the scope will slightly point down. So you will need to touch up the co-alignment.
- Observe closely on the four inner tips of the crosshair lines (cropped by the secondary mirror assembly).
- Shift the secondary mirror to bring all four inner tips on the same track. Then lock down the secondary mirror assembly.
- At this stage, both the outer and inner tips of the crosshair line are all symmetrical on its own rings. And this means the secondary mirror is positioned concentric in the primary's optical path plus the focal plane from the focuser is also square up to the same primary optical axis.

3. Adjust the secondary mirror tilt to collimate the final optical train.
- Adjust focus to bring all three converging laser dots exhibit behind the reflector mirror to a single point.
- Adjust the secondary tilt to line up the three dots on the collimator target onto the same track.
- Check if the converged laser behind the reflector mirror are also concentric on the small bull's eye target.
- If not, the secondary mirror is still offset positioned from the primary optical axis. You will need to iterate the same process in step two to correct this.
- At this point, your secondary mirror aims parallel to the primary's optical axis.

4. Verify focuser travel is parallel to the final optical axis.
- Adjust the focuser from minimum to maximum distance and observe the three laser dots on the collimator target.
- If all three converge and expand symmetrically on the target, your focuser is parallel to the final optical train axis.
- Your scope is ready for the first light and you should only need small or no adjustment to touch up the image.

The above guideline is based on available adjustments on your SCT scope and most RC scopes like the ATRC. The sequence may slightly switched depending on the type of scope, e.g. MaK with fixed secondary mirror in the OTA will be aligned based on the secondary mirror's optical axis.

Clear Skies!
David


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ahopp
sage


Reged: 05/24/12

Re: HoTech SCT Laser Collimator? new [Re: HOTECH]
      #5877570 - 05/22/13 08:59 AM

Maybe David could start a rental service for the collimator, I would happily pay $100 to rent for a week.

Tony


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Kevdog
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Re: HoTech SCT Laser Collimator? new [Re: ahopp]
      #5878608 - 05/22/13 05:25 PM

I have no idea how to shift the secondary on an old CF tube C11. Anyone know? If its not too hard I might give it a go. If it's too involved I might just be happy with "good enough" for now.

Thanks for all the info!


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HOTECH
Vendor - Hotech


Reged: 10/23/08

Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5878830 - 05/22/13 06:43 PM

Hello Kevdog,

There is a thread talked about the collimation result from a C11. You might be interested checking it out.
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5877161/Main...

Clear Skies!
David


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Kevdog
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Re: HoTech SCT Laser Collimator? new [Re: HOTECH]
      #5880319 - 05/23/13 01:57 PM

What a difference. I don't think it's perfect yet, but it is much much better. I didn't have time to let the scope properly cool down, so Saturn was still a bit mushy and the seeing wasn't great so I couldn't push the magnification.

But I turned it toward the moon and that is the sharpest I've ever seen the moon! The craters and other surface detail were all crisp.

I'm happy!


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Kevdog
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Reged: 07/11/12

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Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5880790 - 05/23/13 05:23 PM

Here's the picture of the secondary alignment. You can't see it too well (high ISO on a camera phone, ick!) but its there if you zoom in. It is pretty close!



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HOTECH
Vendor - Hotech


Reged: 10/23/08

Re: HoTech SCT Laser Collimator? new [Re: Kevdog]
      #5883412 - 05/25/13 01:42 AM

Nice co-alignment!
1. You might want to touch up the horizontal lines to be on the target's line by tilting the collimator slightly up just to make sure both the collimator and the primary are squared up.
- Reference the outer tips of the crosshair symmetry on the same track for telescope aiming during co-alignment. I usually adjust one axis at a time to avoid confusion. e.g. only tilt the scope up/down and get both top/down tip to the same ring height. Ignore if the line is on the printed target cross. Then sweep the scope left/right to get both left/right tip to line up on the same ring.
- Referencing the crosshair lines on the target cross for collimator aiming. Adjust the same way but this time is the colliamtor's tilt. In your photo, you will adjust the up/down knob on the fine adjustment stage to tilt the collimator and only observe the horizontal crosshair to line up to the horizontal target line.
- Iterate these steps to perfectly co-align the collimator and the telescope.

2. The secondary mirror assembly shadow seems concentric on the same ring in the photo. This means the secondary mirror is prettry much optically centered in your primary's optical axis. The photo is still little blurry but if you follow the guide line to shift accordingly. Then double check where the centering of the converging laser dots behind the reflector mirror. If all concentric (the outer tip, secondary mirror shadow, and the dots at reflector mirror) the scope is optimized.

Clear Skies!
David


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ahopp
sage


Reged: 05/24/12

Re: HoTech SCT Laser Collimator? new [Re: HOTECH]
      #5883782 - 05/25/13 11:00 AM

David, no comment on the rental idea? You could make more on just 1 or 2 rental over selling one to someone.

Tony


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achille66
member


Reged: 08/15/08

Loc: athens greece
Re: HoTech SCT Laser Collimator? new [Re: mega256]
      #6406046 - 03/02/14 05:03 PM

One question on this marvelous piece of equipment
What happens if the secondary mirror is not removable - fastar compatible.
I have an older c925 and the secondary is not removable from the corrector. I cant seem to understand if my telescope is compatible with hotech ct laser collimator, even after reading the manual! Does anybody know? Thank you


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Christopher Erickson
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Reged: 05/08/06

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Re: HoTech SCT Laser Collimator? new [Re: achille66]
      #6406367 - 03/02/14 07:11 PM

Quote:

One question on this marvelous piece of equipment
What happens if the secondary mirror is not removable - fastar compatible.
I have an older c925 and the secondary is not removable from the corrector. I cant seem to understand if my telescope is compatible with hotech ct laser collimator, even after reading the manual! Does anybody know? Thank you




Yes, it is certainly compatible. In your case you can do most-all of the tests but can only perform some of the adjustments. Arguably the most important adjustments!


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achille66
member


Reged: 08/15/08

Loc: athens greece
Re: HoTech SCT Laser Collimator? new [Re: Christopher Erickson]
      #6407052 - 03/03/14 07:39 AM

Ok i have watched the instructional video and from what i understand i cannot do focal plane adjustment. I think the edgehd have an extra lens in their focusing system which older c925 do not have. Thus all is ok. O e last piece of info on aligning the secondary. We loosen the retaining baffle and play around until its aligned... Do we rotate at all the corrector or not??? Thank you

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dr.who
scholastic sledgehammer
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Reged: 01/05/12

Re: HoTech SCT Laser Collimator? new [Re: achille66]
      #6407524 - 03/03/14 01:11 PM

Another odd and possibly stupid question... The only Alt/Az mount I have is the ES Twilight II. If the OTA is on its side does it matter? The alternative would be to use a EQ mount which I assume would mean adjusting the target to match the angle the EQ mount has the OTA at...

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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: HoTech SCT Laser Collimator? new [Re: dr.who]
      #6407555 - 03/03/14 01:26 PM

Quote:

Another odd and possibly stupid question... The only Alt/Az mount I have is the ES Twilight II. If the OTA is on its side does it matter? The alternative would be to use a EQ mount which I assume would mean adjusting the target to match the angle the EQ mount has the OTA at...




The orientation of the OTA does not matter.


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dr.who
scholastic sledgehammer
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Reged: 01/05/12

Re: HoTech SCT Laser Collimator? new [Re: EFT]
      #6407633 - 03/03/14 02:16 PM

Thank you Ed!

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achille66
member


Reged: 08/15/08

Loc: athens greece
Re: HoTech SCT Laser Collimator? new [Re: Christopher Erickson]
      #6407803 - 03/03/14 04:08 PM

thank you Chris for your answer, now i need to come up with the cash to invest in this magnificent instrument

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