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HoTech 1.25" SCA Laser Collimator - Crosshair

5.0 (17 Reviews) Read Reviews Write Review
Brand HoTech
Part Number SCA-1.25C
Availability available

Product Info

Manufacturer Description

Voted "Hot Product - 2009" by Sky & Telescope.
"There is a tremendous amount of creativity and cleverness being displayed, all backed by a fervent devotion to making the sky more accessible and enjoyable for astronomy enthusiasts at all levels. It is truly inspiring." Robert Naeye, Sky & Telescope Editor in Chief

  • Ideal for collimating Newtonian reflector telescopes. Can be used for SCT collimation, although we do not recommend that. For SCT collimation, consider HoTech's single-dot collimators or the Advanced CT SCT collimator.
  • Uses innovative Self-Centering Adapter technology for most precise centering and collimation
  • Made of aero-space grade lightweight aluminum material and CNC machined
  • 45-deg faceplate with targeting grid allows more convenient alignment from the rear of the telescope
  • Over 65 hours of operation with included CR123 batteries
  • Available in 1.25" and 2" models

Laser Collimator with Self-Centering Adapter (SCA) - Provides Repeatable Installation
The HoTech laser collimator separates itself from all other laser collimators with its innovative self-centering adapter technology (SCA). This mechanism allows precise and repeatable installation in all brands of 1.25" and 2" telescope focusers, thus providing accurate collimation. All laser collimators in the current market have one fundamental problem, slop in the adapting mechanism between the laser collimator and the telescope focuser. This problem is clearly recognized and often discussed among astronomers but so far there has been no definite solution in the market.

No matter how tightly the tolerances machined on the laser collimator or the focuser, a small gap is required to allow installation of the laser collimator. Once the laser collimator is inserted, the required gap becomes a problem. A laser collimator is secured with one or more thumbscrews or unified compression ring. Both methods introduce a very critical issue, namely an off-axis installment that instantly destroys the precision of your collimation instrument along the entire optical axis.

HoTech's Self-Centering Adapter cleverly eliminates the slop by linearly compressing the built-in rubber rings.
By doing this, the diameter of the rings expands to compensate the gap. Because all rings evenly expand radially in diameter from the compression, this automatically centers the laser collimator in the focuser draw tube. And most importantly, the SCA laser collimator can be tightly installed in the focuser for a repeatable installation to provide accurate collimation.

In summary, HoTech's SCA adapter serves three critical functions.
First, its expansion rings accommodate almost all focuser's manufacturing tolerances.  Second, it automatically centers the adapting laser.  Third, it provides at least two evenly distributed circular contacts on the focuser's inner tube surface preventing the adapting laser from pivoting.  Once the slop factor is taken away, you can quickly collimate your telescope in confidence to achieve perfect collimation every time.

Problem Solved with SCA Adapter Technology 

1. SCA Eliminates Drawtube Slop
All drawtubes have manufacturing tolerances. They require a larger diameter to accept various eyepieces and adapters. When a standard collimator is inserted, the gap between the drawtube and the inserting device becomes a slop problem. The rubber rings in the SCA expand radially according to users own adjustment to fill the gaps. This makes your collimator seat firmly in your drawtube, becoming part of your telescope for a secure and repeatable installation.

2. SCA Eliminates unstable locking from thumbscrew or unified compression ring
The optical axis is shifted when the inserting device is locked in by thumbscrew. In some cases, some poorly made unified compression ring can cause unstable tilt when locking in the drawtube due to loose tolerances between the compression ring, inner groove, and the uneven tip of the locking thumbscrew in a drawtube. The SCA adapts the collimator itself without using the thumbscrew or the unified compression ring.

3. SCA Accepts the Imperfection of a Drawtube
Despite small imperfections inside the drawtube like dents, scratches, and uneven burrs, the rubber rings compensate the errors and faithfully center the collimator in the tube. In addition, even if the drawtube is slightly deformed in diameter (egg-shaped), the rubber rings in the SCA will compensate for the differences and faithfully center the collimator. A metal collet design will not be able to transform itself to the deformed shape to compensate the imperfection of a drawtube for a sturdy adaption.

More SCA Laser Collimator Features:

Laser Engraved 45-deg Targeting Faceplate

The targeting faceplate displays the returning laser spot with a clear visual reference during adjustment. That allows you to align your primary mirror from the rear of the telescope eliminating traveling to the front of your scope repeatedly during collimation.

When collimating without the targeting faceplate, you will not be able to adjust the primary mirror in real time referencing the laser dot. In other words, you often get lost on which adjustment screws you used due to traveling back and forth for referencing the direction you have adjusted. This results in considerable time to complete the collimation and defeats the purpose of quick and easy laser collimation. HoTech understands the importance of this, so the faceplate is a standard feature in their laser collimators. All astronomers deserve to have it without paying anything extra!

In addition, the faceplate viewers pattern is laser engraved to ensure a long lasting sharp targeting grid for best visual effects. Unlike other collimators, the target is not a sticker that will peel, or paint that can rub off or chip. HoTech understands that you are paying for a precision instrument that is supposed to be well made.

Finest Projecting Laser Dot

Keeping the laser dot to the finest point is the key to precision collimation. But when you look closely at the laser dot from brand to brand, most laser dots appear large; not really a fine point as you might have imagined. This means that there is guess work involved when you try to center the dot; not just centering the laser dot to the center of the faceplate, but also centering the center of the dot itself. This does not make any sense when you are trying to take the advantage of the collimated laser beam's characteristic which has a low beam divergence, so that the beam radius does not undergo significant changes within moderate propagation distances. In other words, the laser beam size within the collimation distance (laser collimator to the primary mirror and back to the faceplate) should remain a constant fine point. As you know, most laser collimator brands are not really laser manufacturers. They install an off-the-shelf laser module or pointer and align the laser in a tube without REALLY considering the user’s application, namely the operating distance for a laser beam size. HoTech has been designing and building laser modules and systems for over 10 years for various professional industries. We know exactly how a laser should work. We limit our laser beam to the finest size in the correct operating distance for optimal effect. Our understanding and experiences with the laser design permit you to have an effective and precision collimation.

Proprietary Crosshair Laser Collimator Available

With HoTech's proprietary laser crosshair, the user can zero-in the laser with ease during the final collimation on the secondary and the primary mirror. The crosshair model still exibits a precision laser center dot, but with a touch of four extended laser lines from the center dot. The extension lines (crosshair) of the laser dot is the most intuitive way to guide the laser pointing for an accurate adjustment. During the secondary mirror collimation, a single dot laser projecting on the approximate center of the pre-loaded donut is difficult to identify if the laser dot is exactly on the center. The crosshair laser can easily help user to adjust the secondary mirror to point the laser on the exact center with the help of the crosshair line. During the final primary mirror collimation, the returning laser dot often hides into the laser exiting hole preventing user to identify if the returning laser is at exact center of the hole. Again, the crosshair will visually guide the user to center the laser dot with ease even when the center laser dot disappears into the exiting hole. It is a very effective and essential feature to the SCA Laser Collimator in obtaining at even higher degree of accuracy with ease.

High Accuracy Laser Alignment
The HoTech laser collimator is well centered and aligned which are critical factors for an accurate collimation. But you will be surprised that many laser collimators in the market fail in this regard. The reason is in the design and understanding of the product itself.

HoTech has considered all aspect of parameters in their design. Parameters like the alignment mechanism, mechanical and optical structure of the laser itself, and more are taken as part of the laser collimator's design. For instance, some laser collimators actually install an off-the-shelf laser pointer in the casing. It is very cost effective (for the seller), but it inherits numerous problems. In many cases, the laser pointer might not install perfectly centered in the casing due to pointer size variations and the added alignment mechanism. So the laser itself is not positioned on the true alignment point and optical axis. As the result, the laser can never be center-aligned in the enclosure. It is possible to align the laser beam parallel to the optical path but always with an offset along the optical axis. This means the laser beam is off no matter how you center adapt the laser collimator to the focuser. The result of off-centered laser will introduce astigmatism into your telescope.

Light Weight Design and All Aluminum Body Machined with High Precision CNC
Many laser collimator manufacturers give users the wrong impression, big and heavy means rugged and stable. Instead, HoTech engineers successfully cut the unnecessary weight on the laser collimator because they understand that additional weight on a telescope (especially open structure Newtonians) will create imbalance and structure sagging. In addition, the heavier the device is, the more inertia it will have during an impact from an accidental drop. In such an accident, the inertia force can cause more damage to the internal alignment mechanism because there is more energy required to dissipate from the impact. Therefore, the lightweight design on this laser collimator makes you gain reliable precision collimation. And, of course, Hotech laser collimators use aerospace grade lightweight aluminum material and are CNC machined with the tightest tolerances, then sand blasted and anodized to protect them from harsh environments. Nothing has been sacrificed while you get a long lasting state-of-the-art collimation instrument.

Long Lasting Battery Life
By using a CR123, 3V battery as the laser power source, HoTehc's laser collimator has over 65 hours of continuous use battery life time. The included CR123, 3V lithium battery operates well under a typical cold night and it has a 10-year shelf life. This is a great advantage since you don't have to worry about changing the tiny, hard to find cell batteries frequently in the dark like other collimators.

Collimation for your SCT
Commercially made SCTs all have slight optical and mechanical alignment errors. The error typically is in the centering of the secondary mirror. As a result, when a laser is installed and emitted from the focuser, the beam will seldom return dead center, even though star testing would indicate perfect collimation! In addition, the secondary mirror (convex shape) magnifies any error by about 5 times. The error of deviation for a typical well-collimated SCT will return laser beam at around 0.125" to 0.25" off center. In order to compensate the optical and mechanical alignment errors of SCT, a different collimation approach is required in comparison with Newtonian telescopes. If the procedure is followed through correctly, users can still accurately collimate their SCT.

By default, the laser will have to be positioned in the optical center of the SCT. The HoTech SCA laser collimator automatically eliminates the focuser slop without using the thumbscrew and center-positions itself on the optical axis. For SCTs, the primary mirror is fixed, but you can collimate by adjusting the secondary mirror to a point parallel to the optical axis.

There is an one-time-only preparation that you need to do for SCT laser collimation using this collimator. First, install the SCA laser collimator and premark the laser position on the target grid of the collimator when your telescope is collimated from the factory or from your star collimation. Then when you check for collimation next time, just adapt the SCA laser collimator on the focuser, 2" or 1.25", and see if the laser falls on the premarked laser position. If not, adjust the alignment screws on the secondary mirror to move the returning laser dot to the premarked postion on the target grid. See illustrations below.


Diffraction Grating Pattern Lens on the SCA Laser Collimator

Since HoTech's SCA Laser Collimator is already accurate with the SCA technology, fine laser dot, and the built-in 45 degree faceplate, there is no need to use the DFG pattern to align the primary mirror of a Newtonian telescope. The purpose of using the DFG pattern is to eliminate gross misalignment the primary mirror. The user aligns the primary mirror by referencing the shadow of the secondary in the projected DFG pattern on a wall, and the user counts the DFG dots around the shadow to center in the shadow. This method cannot achieve accurate alignment because the gap between each dot can make a big alignment difference. At the final alignment stage, the user must bring the laser dot back to the laser exit (the center of the 45 degree faceplate). HoTech's built-in 45 degree faceplate allows you to align your primary mirror from the rear of the telescope eliminating traveling to the front of your scope repeatedly during collimation like other collimators. Therefore, there is no need to use DFG lens in conjunction with HoTech's SCA Laser Collimator.

Reviews

5.0 (Based on 17 Reviews) 100% of reviewers recommended this product.
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    1. Guest

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      Review by Omar R.
      1547251923
      Jan 11, 2019

      5.0 Collimator

      Pros:

      Cons:

      Comments:

      The collimation worked perfectly. i was able to properly align the mirrors in a matter of minutes

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      Review by John M.
      1542513765
      Nov 17, 2018

      5.0 Works as advertised

      Pros:

      Cons:

      Comments:

      I had never used a laser collimator before this one; it worked great and was simple to use.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      Review by Mark B.
      1542392455
      Nov 16, 2018

      5.0 Great product.

      Pros:

      Cons:

      Comments:

      Works as advertised. I own a cheaper laser collimator that would wiggle in the barrel. This Hotech collimator holds nice and firm giving a more accurate alignment. With the laser crosshair, aligning the mirrors is much easier. Worth the extra money to me.

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by Jonatan S.
      1521243485
      Mar 16, 2018

      5.0 HoTech Cross Colliminator

      Pros:

      Cons:

      Comments:

      I've a 20" F5 Dob. Very helpful for me bcs I can see the laser dot after passing the focuser. Wth my previous laser colliminator I've to see the laser dot in the upper cage in angle (not precise) & hv to walk back-forth to adjust it (unless you hv someone to help you to adjust the knops behind the mirror). -----Wth HoTech Cross I can adjust the collimation up-down/ left-right until in the centre from behind the mirror (no need to walk) by myself. Wth the cross ➕ I can centre the dot precisely rather thn guessing.

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by yoshihiro a.
      1501396721
      Jul 29, 2017

      5.0 HoTech 2" & 1.25" SCA Laser Collimator - Crosshair

      Pros:

      Cons:

      Comments:

      Very easy to use

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      Review by Brent R.
      1496843171
      Jun 7, 2017

      5.0 Works fantastic. Glad after all

      Pros:

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      Comments:

      Works fantastic. Glad after all my research i chose this one.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      Review by Young-hun K.
      1492397434
      Apr 16, 2017

      5.0 very good

      Pros:

      Cons:

      Comments:

      very good

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by Robert S.
      1487319572
      Feb 17, 2017

      5.0 A wonder to be sure....

      Pros:

      Cons:

      Comments:

      Firstly I must say I am a novice in regard to astronomy
      and was rather perplexed about how to collimate my 12'' skywatcher
      dobsonian in fact I had never heard the term ...anyway I was advised
      to purchase this item and am completely glad I did ..the very day it
      arrived I read the instructions and within a short time I was gazing at
      the moon ....it is a incredible tool
      in regard the seller again I am completely delighted
      it arrived as if passed to my hand ..very well wrapped
      in short buy it and you will not be disappointed

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by raymond h.
      1483808079
      Jan 7, 2017

      5.0 2” HoTech Crosshair Collimator

      Pros:

      Cons:

      Comments:

      I really am happy with this purchase. I’ve used this to collimate a 6” an 16" dobs and the improvement in viewing was immediate. It also showed me how badly my 16" truss scope was prior to using the HoTech.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      Review by Sand79 of KC MO.
      1454716800
      Feb 5, 2016

      5.0 Impressed

      Pros:

      Strong Construction,Easy to Use,Accurate

      Cons:

      Comments:

      I own a few dob telescopes and have always used a Cheshire for collimation. A friend recently purchased a laser collimator (from one of the two big-brand telescope companies) and I was amazed how fast and accurate it was. I then had to get one myself. I performed a lot of research on various astro forums and this model kept coming up as an increadle value. There were quite a few comments about the quaility control being much better than the two big-brand mainstream models, and stories of needing to return those a few times to get an accurate one. Based on this advice I ordered and have not been disappointed. Worked right out of the box, and double-checking collimation with the Cheshire and star tests, it seems spot-on. I highly recommend this model if you're loking for a laser collimator.

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by Straightmak of Stalybridge, UK.
      1410307200
      Sep 9, 2014

      5.0 Amazing device

      Pros:

      Accurate,Strong Construction,Easy to Use

      Cons:

      Comments:

      I cannot praise the HoTech laser collimator enough. This self centring model is ideal. I can travel to a dark sky site and collimate my F4 Schmidtt Newtonian in seconds! Wish I'd had one years ago!

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by C8er of New Zealand.
      1374969600
      Jul 27, 2013

      5.0 Excellent and very easy to use.

      Pros:

      Accurate,Easy to Use

      Cons:

      Comments:

      Has allowed me to do very fast, accurate, and easy collimation of a newtonian. Precision apparatus to center it in the focuser tube is great and scope can be very quickly and easily collimated. I got the cross hair version and that certainly makes collimating the primary easier then it would be with the non cross hair version.

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by LeCarl of Canada, Quebec.
      1354320000
      Nov 30, 2012

      5.0 Work great, as expected

      Pros:

      Strong Construction,Accurate,Easy to Use

      Cons:

      Comments:

      I bought this to replace my cheaper agena/antares collimator. (I have experiences with collimator, newtonian build, from 16 inch to small ones)

      It work great, crosshair is amazing, very fast too, as expected, feel strong, as manual say sometime it is hard to put an get stuck on focusser(this mean it was tight fit)

      Cons: not cheap, can't do better than a properly calibrated cheaper agena laser collimator (with the hidden 3 screw covered with silicone), and you can't adjust the hotech, because it don't have the 3 screws... (maybe one day it will take fine adjustment)
      Furthermore, I suspect that is not as accurate than the very fine tuned cheap ones... (I can't do repeatable straight precise on centre, on and off, and I can't do successful rotation, mean it is a bit off)

      Otherwise, if you have money, go for it, it is the best (for +-$$$) right out of the box, I give 5 stars for this

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by DAVE of Nice, CA.
      1330128000
      Feb 24, 2012

      5.0 Excellent!

      Pros:

      Accurate,Strong Construction,Easy to Use,This made alignment easy

      Cons:

      Comments:

      My first alignment took 10 minutes! Just the best ever! Amazing.

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by Astronewb of Canton, CT.
      1326153600
      Jan 9, 2012

      5.0 Super easy to use

      Pros:

      Accurate,Compact,Easy to Use,Strong Construction

      Cons:

      Comments:

      This collimator is so easy to use, a caveman could do it..:) Recently received a Dobsonian that arrived with the secondary swinging loosely and had to install the primary. Between the Cheshire cap and this collimator, I was viewing DSO's in 10 minutes. I would recommend this to anyone if they don't already have one.

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by Astronewb of Canton, CT.
      1319241600
      Oct 21, 2011

      5.0 Excellent tool

      Pros:

      Accurate,Strong Construction,Easy to Use

      Cons:

      Comments:

      Used this tool to collimate a new ES Comet Hunter Mak-Newtonian. Scope arrived well out of collimation (laser dot 1/16-1/8" out of primary mirror reference circle). Took about 5 minutes with this Hotech to collimate secondary and primary mirrors. Worth every cent you pay.

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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      Review by Starman3 of Klamath Falls, Oregon.
      1272758400
      May 1, 2010

      5.0 This is an excellent product!

      Pros:

      Strong Construction,Quality Lenses,Compact,Accurate

      Cons:

      Comments:

      I use this collimator every single time I use my 16" Meade Dobsonian Telescope and it is very accurate and easy to use! The other night, here in Oregon, we had a half moon and after collimating with the HoTech Laser Collimator, I got the most crystal clear, sharp pictures, I have ever seen, using a 2" 2x Barlow with a 1.25 adapter and a cheap 4mm eyepiece! Thats at (and I don't believe this myself!) 914.50 magnification! ( check it out: 1829mm focal length divided by 4mm magnification = 457.25 X 2 (2X Barlow!)equals 914.50 magnification! Wow! And I mean, "tack sharp too! What more can I say?.....Buy it!

      Bottom Line: Would you recommend this item? Yes
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      This review was provided courtesy of AgenaAstro.com

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