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Hotech - Advanced CT for 2 " Focuser with SCA-TA125 (1.25” T-Adapter) Laser Collimator


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Available - Ships in 3-5 Days

Manufactured by: HoTech


Founded in 2002, HOTECH is a leading company in the opto-electronic industry serving the Astronomy community the world over. Throughout the history of HOTECH USA,  the company has continuously brought forward innovative and proprietary technologies to develop state-of-the-art, next-generation products offering a competitive edge to Astronomers everywhere.  Enter the HOTECH Advanced CT Laser Collimator, HOTECH's latest device to improve visual accuracy in the Schmidt-Cassegrain telescope ( and many other Cassegrains) and is designed to replace the much more complicated and costly Wavefront Interferometers as collimation tools for larger aperture reflectors.

The HOTECH Advanced CT Laser Collimator samples the entire optical system (primary, secondary mirror, and eyepiece axial position) with a simulated large aperture flat-wavefront light source generated by three parallel lasers positioned behind the supplied Target Plate.  By using three perfectly aligned laser beams it emulates the parallel rays coming from a distant star. The beams then pass through the telescope twice to magnify any error in the entire system.  Because of this redundancy even tiny collimation errors become apparent and can then be corrected.

The only user accessible collimation alignment point on a Schmidt-Cassegrain Telescope is via the (3) secondary mirror alignment screws located behind the secondary mirror at the front of the Telescope  Therefore, you only need to adjust the three alignment screws to adjust the secondary mirror to move the three laser spots onto the same circle on the target plate. This limited adjustment makes the collimation simple to perform. The target plate provides a clear view of the mirror alignment  when the three lasers are reflected back on the target. The Target Plate should be held in place at the appropriate height by the included adjustable tripod head. Finally, the appropriate Reflector Mirror (1¼" or 2" - your choice depending on the size of your focuser) is inserted it in the visual back (imaging use) or into the diagonal (visual use) of the Scope. That's it. Start Collimating!


- Collimation without using a referencing star
- Indoor or outdoor - day or night
- Focus stays at final view setting
- Set-up within focal length distance from your telescope
- One person operation
- Portable and simple to setup and use
- Works on CT, SCT, SN Mak, & RC


HOTECH SCA precision prime focus T-Adapter (1.25 inch)  - INCLUDED WITH THIS ADVANCED CT COLLIMATION PACKAGE. 

HOTECH has found the solution to sloppy camera to telescope connections - the Self-Centering Camera T-Adapter for Astro-Imaging.  The Self-Centering Adapter (SCA) mechanism  provides consistent and reliable connection between your telescope and camera.  The SCA T-Adapter fits any make telescope that uses a 2" or 1.25” focuser or visual back. The SCA brings your Camera to the Closest Optical Axis in the Drawtube or Visual back. For BEST Imaging results, it is essential to position your camera firmly in and on the optical axis   The SCA T-Adapter center-loads the camera in the drawtube or visual back with a simple tightening of a compression ring forcing the built-in rubber rings outward evenly,  The camera. is now solid and secure.


  • SCA Provides 360 deg. rubber square rings contact for the most secure and reliable adaption in your focuser
  • SCA Brings your Camera to the Closest Optical Axis in the Drawtube/Visual back for BEST Imaging Result
  • SCA Eliminates Drawtube/Visual Back Slop
  • SCA Eliminates unstable locking from thumbscrew or unified compression ring
  • SCA Accepts the Imperfection of a Drawtube/Visual Back SCA Short Profile Prevents Oscillation
  • SCA Damps Vibration
  • SCA Accepts Standard Filter Threads

IF A USER  has any questions about the setup process, the ACT Laser Collimator comes with a well illustrated and written Owner's Guide, 7 pages in length which will definitely clear up any confusion during initial setup.

Amateur Astronomer magazine Summer 2014:  Robert Reeves wrote this article in the Star People: Real People feature











Product Series

HOTECH New Comprehansive Collimation Videos!

Collimate your SCT with Confidence!

Innovation brings Affortable and Portable Collimation into Reality

Since the invention of the Cassegrain Telescope in 1672 by the French sculptor Sieur Guillaume Cassegrain, the Cassegrain Telescope has evolved into various derivative designs such as the more popular Ritchey-Chrétien, Dall-Kirkham, Schmidt-Cassegrain, and Maksutov-Cassegrain. The designs have gained their popularity because of their compact and simple to produce design. With different designs, star collimation is and has always been the only effective method to collimate for Cassegrain telescope owners.

Now, backyard astronomers have an alternative to achieve excellent collimation conveniently using the Advanced CT Laser Collimator. The Advanced CT Laser Collimator brings the collimating star to your telescope within arm reaching distance. With its short range capability, you can perform collimation indoors - day or night - without being subjected to weather conditions. And best of all, this new collimator utilizes a clear and simple-to-read, large target display for the telescope alignment diagnostic. This large target display is positioned within a short focal distance of the telescope which allows you to collimate without guessing.


No Star Required to Collimate

In order to achieve an accurate star collimation, normally the amateur astronomer requires good seeing conditions with no cloud, no wind, stable temperature, no light pollution, a well-aligned telescope mount tracking system, telescope optical tube assemble (OTA) thermal equilibrium, and a good visible magnitude star. The visual quality of the referencing star is greatly affected by the prescribed factors most of which are all in Gods hand as you can see in the photo. Adjusting the collimation is guessing game where you move between front and the back of the telescope adjusting the corresponding alignment screw and holding your breath peeping through a high magnification eyepiece referencing the concentricity of the unstable defocused image. This can be an incredibly frustrating experience.

An artificial star can never simulate a real star because it is impossible to collimate with the telescope focus set at infinity. After artificial star collimation, you will need to adjust your focus back to infinity to view a real star by moving the primary mirror to a different position. The distance the primary mirror has been adjusted can accumulate mechanical tolerance errors. For some of the mass produced SCTs, the “sticky baffle” on the primary mirror focusing mechanism may also cause mirror-flop. If a mirror-flop has ocurred, it will affect the alignment position which in turn will render the collimation useless. Ideally, It is best to collimate your optics at the same viewing focusing position without major optical displacements to correspond to the final view setting. The Advanced CT Laser Collimator can accomplish this task without all the possible accumulated errors.

The large target display on the Advanced CT Laser Collimator brings you a clear visual queue of three projecting laser dots as the alignment reference at a very comfortable visual distance providing an accurate axial alignment error diagnostic. And during the entire collimation process, no major focusing is needed, thus minimizing the possible accumulated errors from the focusing adjustments. The referencing adjustments are made by bringing the three clearly discernible projected laser dots projected on the target, into a concentric ring. No more peeping through the eyepiece looking for a changing, ambigu star image. This alternative collimation method saves precious observing time by collimating the telescope and preparing the viewing programs at dusk or before dawn without the influences of the external environmental conditions.

Collimate Within Focal Distance From Your Telescope

The Advanced CT Laser Collimator does not require long focal distances to achieve high-accuracy collimation. Utilizing the installed flat mirror at the focal point (eyepiece location), the collimator lasers double-passes both your primary and secondary mirrors and magnifies the alignment errors to a higher accuracy level. In addition, it also cuts the collimating distance in half achieving near-field alignment process. The collimator is stationed within your telescope's focal length directly in front of your telescope. Setting up for collimation, you will be standing between the telescope and the collimator aiming both the telescope and the collimator at each other. Then you will adjust the secondary mirror knob to bring the returning lasers on the same track. This is a very convenient one-man operation.

At a Fraction of the Cost of Wavefront Interferometer Technology The state-of-the-art advanced laser optical alignment technology used in the Advanced CT Laser Collimator achieves the same rough alignment function of a costly large aperture interferometer commonly use in high-energy labs at a fraction of its cost.

The Advanced CT Laser Collimator uses three collimated lasers, evenly spaced apart, to sample large aperture optical elements in your telescope.


The three parallel laser beams completely simulate the light path (flat-wavefront) from a distant star and pass through the entire telescope’s optical elements and reflect back to its target for a complete and accurate double-pass diagnostic reading of your telescope optical alignment. This innovative collimation technique and technology enables the amateur astronomer achieving far-field collimation as a near-field process.

Precision CNC Machined Panel and Components

This beautifully designed instrument is precision machined from a solid block of aero-space grade aluminum. It is then hardened and anodized to keep the entire mounted laser system thermally stable allowing you to achieve accurate collimation. The rigid, ultra thin profile, and light-weight design makes the unit portable and simple to setup and use.

Collimates All CT, SCT, Makustov, & RC

The Advanced CT Laser Collimator simulates a real distant star light path, and as a result it can collimate most telescopes which primarily rely on star collimation. The collimation technique can be implemented on any size telescope. The current production model is designed to collimate telescopes with a primary mirror greater than 7-1/5-inches and a secondary mirror obstruction diameter less than 6-1/2-inches. For other larger sized telescope, please email or call us for custom sizes.

Additional Information

Name Hotech - Advanced CT for 2 " Focuser with SCA-TA125 (1.25” T-Adapter) Laser Collimator
Manufacturer HoTech
Model ACT-M2+SCA-TA125
Manufacturer Part No ACT-M2+SCA-TA125
Alignment Procedures Triple laser collimation
Attachment Tripod (target plate) , visual back or diagonal (reflector mirror)
Construction Hardened, anodized aluminum, CNC precision machined
Design Optical laser
Field Flattener Optional accessory
Fine Focus Yes
Laser Class II
Laser output power 1mW
Laser wavelength visable red 632nm
Material Aerospace grade aluminum
Mounting connections 1/4 x 20 thread
Mounting to telescope visual back or diagonal
Power Supply (1) CR123 3V lithium battery
Tripod Adaptable Yes (recommended)