Optec #19740 TCF-Leo 3-inch focuser with FocusLynx controller

Optec engineers have developed a new, low profile, yet extremely robust 3-inch focuser for telescope installations where back-focus is at a premium. With the width of a typical 1-1/4" eyepiece, the TCF-Leo provides a unique focusing solution for the Celestron EdgeHD and other telescopes with limited flange-to-focus distances. The proven FocusLynx control system is included with every TCF-Leo and can be expanded to provide control for a second focuser. The FocusLynx system includes optional 802.11 WiFi and Hand Control accessories.

The unique shape of the TCF-Leo is designed to fit neatly between the lock and focus knobs of the Celestron EdgeHD C-11 telescope OTA. With a center-to-edge distance of about 2.2-inches (55mm), the TCF-Leo works exceptionally well with Innovation Foresight's On-Axis Guider, providing clearance for large cameras and filter wheels above either of the flat edges of the TCF-Leo. Additionally, the TCF-Leo's 3600 receiver fits directly on to the large 3-inch port of the Perseus Instrument Selector for ultra-fine focus of a large format camera.

For owners of the EdgeHD Celestron C1400 telescopes, Optec offers a set of replacement knobs for the original lock knobs which provide clearance for the TCF-Leo. Our #19792 Sure-Lock Mirror Support Clutch upgrade includes two brass replacement lock knobs that are easily installed without tools.

With standard Optec interfaces on both telescope and camera sides, nearly any telescope imaging system can be configured. Specify any of our OPTEC-3600 telescope mounts or contact Precise Parts for a custom adapter to fit any telescope.

As a full 3-inch focuser, the TCF-Leo drawtube accepts any of our OPTEC-3000 adapters developed for the TCF-S3 and TCF-Lynx3 heavy duty focusers. The optional Precision Centering Adapter allows any large 2-inch diagonal or eyepiece to be added behind the focuser.

Visual users will appreciate the FocusLynx Hand Controller with fine-focus rotary knob for no-touch operation of the telescope focus. A special discounted price for the FocusLynx Hand Controller is available at purchse.

A range of Optec 3600 Telescpe Adaptors can be see

Other adaptors can be obtained at Precise Parts

Camera Sider adaptors can be seen HERE

Other adaptors can be obtained at Precise Parts

Technical Specs:

TCF-Leo Specifications

Overall Thickness: 1.25" (31.8mm) to 1.6" (40.6mm)
Focuser Travel: 0.35" (8.9mm)
Focuser Midpoint: 1.425" (36.2mm)
Total Step Travel: 112,000 steps
Step Resolution: 0.08 microns
Weight: 1lb. 14 oz. (0.85 kg)
Payload Capacity: 20-lbs. (9 kg)
Telescope-side Mount: OPTEC-3600 dovetail
Camera-Side Mount: OPTEC-3000 3-inch drawtube
Control System: FocusLynx Controller (included)

FocusLynx Controller Specifications
Functional Specifications:

Stepper Motor Control: bipolar and unipolar stepper motors,
Resolution: 16-bit controller with 65,535 step range per focuser,
PC Connectivity: USB/Serial, Ethernet, or optional 802.11 WiFi,
Hand Control: Optional 2-button with Digital Read-Out,
WiFi Connection: Optional 802.11b/g compatible,
Second Stepper: Optional plug-in daughter board,
Input Power: 12VDC univeral power supply (110 to 230VAC input),
Alternative Power: Field battery voltage (13.8VDC) with optional automotive cigarette lighter plug,
Software Drivers: ASCOM local server, X2 native drivers for TheSky X

FocusLynx Port Connections:

Focuser 1: RJ45 socket for standard Cat-5e/Cat-6 to focuser,
Focuser 2: Optional second stepper board for RJ45 socket,
Power: 12VDC input, 2.5 x 5.5mm plug, center pin positive,
Network: Standard RJ45 Ethernet socket,
Hand Controller: RJ22 socket for standard telephone handset cord,
Serial: RJ12 socket for Optec USB/Serial cable (included).

Optec Gemini Focuser and Rotator

Optec engineers have developed a completely new concept for combining telescope focus and camera rotation functions into a single robust, yet compact package. Rather than simply adding a rotator onto the end of a focuser drawtube, Gemini was designed from inception with a rotating drawtube providing superior strength and rigidity for heavy camera payloads. Featuring four lead-screws and four linear bearings, Gemini can easily handle 10-kg. (22-lbs.) payload packages without flexure. Full 360-degree rotation is a built-in function of the Gemini with a full 1/2" of linear travel. At the midpoint, Gemini measures a mere 2.45" or about 62.2mm in thickness.
Temperature Compensation:

Like all Optec focuser products, Gemini includes a remote temperature probe for automatic temperature compensation. Simply attach the temperature probe anywhere in the linear response zone of your OTA (usually the tube or truss assembly) and Gemini will automatically keep the camera package in sharp focus. The Gemini Commander software provides a convenient wizard to help determine your telescope's TC or temperature coefficient.

To maintain a flat, rigid base for heavy camera packages, Gemini's shell consists of two parallel plates machined from MIC-6 tool plate providing flatness within 0.001" (25 microns). Seven precise stand-off spacers maintain the 2.2" separation of these plates. The rotating drawtube is moved linearly with 1/2" of total travel using a premium timing belt driven by a high torque stepper motor. The entire package is accented with a beautiful carbon fiber wrap. Dual RJ45 connectors provide connection to the Gemini Control hub. The independent rotating drawtube is supported by a custom X-cage bearing system supported by large, 6mm chrome ball bearings.
Dual Function Control with Multiple Options
Support for Multiple Telescopes:

Featuring identical OPTEC-4300 mechanical interfaces front and back, the Gemini can be easily fitted to most any large telescope OTA. Recessed oval point setscrews provide three-point direct contact with the heavy wall OPTEC-4300 dovetail mount. Gemini's clear aperture of 3.75" is maintained through each adapter, passing even large light cones through to the camera image plane without vignetting.

On the camera side, the Gemini package now includes our #19830 OPTEC-4300 to DSI threaded adapter. This part converts the camera side to a receiver for any of our Optec-DSI 3.5 High Performance spacers configurable to 1/4" increments when additional back-focus spacing is needed.

Currently designed telescope adapters include support for the AG Optical iDK's, Celestron, Ceravolo Optical Systems Astrographs, Meade 16-inch class SCT, Plane Wave Secure-Fit, and Takahashi telescopes.

Additional adaptors are available through Precise Parts

ultiple Ways to Connect:

The Gemini Control hub acts as the central controller to link both focuser and rotator to any control PC. The hub includes communication ports for Serial and USB (using Optec's USB/Serial cable) and wired Ethernet Network protocols as standard. An optional WiFi board and antenna can be added and installed at any time. Focuser and Rotator ports are available at the top of the Gemini hub with 12VDC Power, Network, optional Hand Control, and Serial connection ports available at the bottom.
Complete Package includes Hand Controller:

Each Gemini package comes complete with everything needed to connect. The Gemini package includes our updated Gemini Hand Controller which allows jiggle-free manual control while at the telescope. Now featuring a rotary encoder and integrated thumb knob, exact focus adjustments can be made without touching the telescope or focuser.

Our precision external temperature probe, power supply, and ultra-flat Ethernet cables round out a complete integrated package.

Contact Optec Sales or any of our Dealers for a system specifically configured for your telescope rig or observatory.

Coming Soon - 802.11 WiFi Option:

Using the ASCOM Local Server model, Optec's Gemini Commander software allows multiple clients to connect simultaneously to the Gemini hub. Soon to be released embedded webservers in the wired Ethernet and WiFi connections enable Gemini to generate a control interface accessible through any web browser or smartphone. Free Android and iPhone applications search the local network and load the interactive webpages. Because these pages are generated by the hub itself, once you are connected, there is no further configuration required: just connect to Gemini and enjoy remote wireless focus control with the optional 802.11 WiFi add-on.
Gemini Commander Software

Visit the Gemini Software Downloads Page for the latest updates and ASCOM driver, Gemini Commander control software and additional resources.

ASCOM StandardsGemini Commander creates an ASCOM Local Server or hub to allow multiple clients access for communication and control of the attached focusers. By using the local server model, Gemini offers an easily configurable user experience for all Windows ASCOM programs.

Technical Specs:

Focusing Rotator Physical Specifications:

Clear Aperture: 3.75" (95mm)
Back-Focus Usage: 2.2" to 2.7" (55.9 to 68.6mm)
Focuser Travel: 0.5" (12.7mm)
Focuser Resolution: 0.11 microns per step
Rotator Resolution: 600 steps per degree
Minimum Overall Thickness: 2.2" (55.9mm) [Full IN position]
Dimensions: 9.4" x 7.4" (239mm x 187mm)
Weight: 6 lb. 6 oz. (2.9 kg)

Gemini Controller Hub Specifications:
Controller Hub Specifications:

Length: 5.1" (130mm)
Width: 3.2" (81mm)
Height: 1.0" (27mm)
Weight: 10 oz. (285 g)
Mounting Holes: Four 4-40 x 1/8" depth (reverse side)
Case Material: 6061 aluminum, anodized black.

Gemini Hub Port Connections:

Focuser: RJ45 socket for standard Cat-5e/Cat-6 cable to Focuser port,
Rotator: RJ45 socket for standard Cat-5e/Cat-6 cable to Rotator port,
Power: 12VDC input, 2.5 x 5.5mm plug, center pin positive,
Network: Standard RJ45 Ethernet socket,
Hand Controller: RJ22 socket for standard telephone handset cord,
Serial: RJ12 socket for Optec USB/Serial cable (included),
Wireless: 802.11 WiFi option (coming soon).

The following Extension sets are available

Stock #19889
DSI 3.5 Extension Tube Set, 4-piece set

Includes: 1/2", 3/4", 1", and 1-1/2"
Possible spacer combinations:
0.5" through 3.25" with 1/4-inch increments plus 3.75" with all spacers combined. (See Table for combinations.)

DSI 3.5-inch Extension Ring
List Price: $175
Stock #19890
DSI 3.5 Extension Tube Set, 5-piece set

Includes: 1/2", 3/4", 1", 1-1/2", and 3"
Possible spacer combinations:
0.5" through 6.25" with 1/4-inch increments plus 6.75" with all spacers combined.

Optec Lepus Telecompressor

The Optec Lepus 0.62X is a 4-element telecompressor designed by Optec engineers to work with newer, well-corrected Schmidt-Cassegrain telescopes such as the Meade ACF and the Celestron EdgeHD series telescopes. Also known as a focal-reducer, the Lepus provides a 0.62X reduction of the telescope's effective focal length. Lepus works well with most mid-size CCD cameras and Digital SLR cameras having sensor diagonals up to 28mm.
Designed for Corrected Schmidt-Cassegrain Telescopes

Optec's NextGEN series of telecompressors were designed to correct the coma inherent in the classic Schmidt-Cassegrain Telescope (SCT). With optical design improvements by Meade and Celestron, the NextGen series would overcorrect for coma and therefore became unsuitable for use with the ACF and EdgeHD optics. Additionally, image sensors were increasing in size and the addition of filter wheels, off-axis guiders, and adaptive optics units required more back-focus distance between telecompressor and camera.

Lepus is optimized for 100mm of distance between the last lens surface and the image plane. Measured from the telecompressor flange, this distance works out to 105mm as shown at left. Assuming a native focal ratio of f/10, the Lepus 0.62X will reduce the effective focal ratio to approximately f/6.2. Shifting the image plane outward will provide additional reduction but a loss of star quality at the edge of the images. The optimal distance for most SCT's is 100mm with the exception of the C9.25 EdgeHD SCT.

Designed for Midsize CCD's and DSLR's

Lepus can will deliver a fully unvignetted image 22mm in diameter, but will provide well-corrected images out to 28mm with a small amount of light fall-off. Flat fielding is recommended for best results. See Optec's line of Alnitak flat-fielding devices for additional details.

The NGC2818 image at left was provided by Ronny Kaplanian and taken with his Celestron C9.25 EdgeHD, Lepus-HD C9.25 Edition telecompressor, and his Starlight Xpress SXVR-M25C camera in a monochrome mode with separate RBG filtered images. The image sensor on the SXVR-M25C measures 23.5mm x 15mm for a diagonal measurement of nearly 28mm. The image was combined and further processed by Terry Hancock with only slight cropping to remove the stacking artifacts. Click here for a full size image in pdf format.

Lepus HD Telecompressor
For Celestron Edge HD Telescopes

Lepus 0.62X Telecompressor lens system mou
nted in 2x24tpi threaded mount for direct attachment to Celestron EdgeHD scopes.
Close coupled mount provides optimal image quality by maintaining a minimum distance between EdgeHD corrector optics and Lepus telecompressor lens grouping.

The back focus distance is reduced to 100mm on
axis and maintained by a camera specific mount

Optec - Alnitak Flip-Flat Flat Fielder

Alnitak Astrosystems' flagship product, the Flip-Flat, is a robotic lenscap and flat field illumination source for small to medium size refractors.

With hundreds of Flip-Flats already in the field being used by satisfied customers, were confident that our product continues to meet the needs of discriminating astro-imagers around the world.

The Flip-Flat employs advanced electroluminescent lamp panel technology to provide a uniform source of illumination for the production of high quality flat field frames necessary for serious astroimaging and photometric work. With the Flip-Flat, on-demand flat fields with uniformity errors less than 1% are now possible.

In addition to providing excellent flat fields, the Flip-Flat protects the objective lens of the telescope from dust that typically plagues remote installations where the user cannot manually replace the lenscap after an imaging session. The Flip-Flat is easily mounted to the front of any telescope tube (or rigid dewshield) with an OTA outside diameter between 4" (100mm) and 8-1/8" (206mm). The Flip-Flat is attached to the telescope OTA with industrial nylon zip straps and easily removable for transport and storage.

A simple Windows interface provides the ability to open and close the Flip-Flat and turn on the light source. The intensity of the light can be adjusted to one of 255 levels.

Lamp Diffuser Diameter: 7.7" (195mm)
Lamp Illumination Diameter: 6.7" (170mm)
Control Box Dimensions: 2.25" x 3.15" x 4.2" (57 x 80 x 106mm)
Weight: 1 lb. 6 oz. (0.6 kg)
Lamp Pivot Arm: 6.1" (155mm) length
Range of Pivot Arm: 95-degrees
Power requirements: 5VDC provided by USB interface

Alnitak Software Compatiblity: Windows XP, Vista, Windows 7 and 8.
Command Line Program: AACmd.exe

Visit the Alnitak SOftware downloads page for the latest Quick Start Guide, Alnitak Installation Manual and Software Reference Guide, and Serial Command List.

Technical Specs:

#19050 - Alnitak Flip-Flat, OTA size: 4" to 6"

The #19050 Flip-Flat package includes the lamp controller, motor arm, OTA bracket to center the lamp over OTA dew shields measuring 4" to 6" in diameter, a pair of industrial zip straps, USB cable, and software. Fully illuminated lamp is 6.7" (170mm) in diameter.

#19051 - Alnitak Flip-Flat, OTA size: 6" to 7-5/8"

The #19051 Flip-Flat package includes the controller, motor arm, OTA bracket to center the lamp over OTA dew shields measuring 6" to 7-5/8" in diameter, a pair of industrial zip straps, USB cable, and software. Fully illuminated lamp is 6.7" (170mm) in diameter.


Optec - #19056 - Alnitak Flat-Man, up to 8-1/8"

For the imager who doesn't need the robotic capability of the Flip-Flat, the Flat-Man is now available. The Flat-Man uses the same technology as the Flip-Flat, but is manually placed on the OTA for flat field imaging. The only power you need is a USB cable, and our Windows XP software will light and control the brightness of the Flat-Man. Simply rotate your telescope until the dewshield is pointed straight up and place the Flat-Man centered on your scope.

The Flat-Man is an affordable means to achieve excellent flat fields. For dewshield OD's up to 81/8 inches.

#19056 - Alnitak Flat-Man, up to 8-1/8" - Price: $349
Add to Cart

The #19056 Flat-Man package includes an additional expansion ring allowing use with OTA's having dew shields up to 8-1/8" in diameter, USB cable, and software. Fully illuminated lamp is 6.7" (170mm) in diameter.

Alnitak Software and Technical Downloads:

The Alnitak Control Software can be downloaded from our downloads page and includes the AACmd command line program for use with ACP, CCD AutoPilot, Maxim D/L and other astronomy automation programs.

Visit the Alnitak SOftware downloads page for the latest Quick Start Guide, Alnitak Installation Manual and Software Reference Guide, and Serial Command List.


Optec Pyxis 3 Inch Rotator

The Pyxis 3-inch has a full 3 inches of clear aperture and is designed to hold large instrument packages without flexure or wobble. A 6-inch bronze worm gear and stainless worm rotate the center tube with a resolution of 0.01875 degree per step from the stepper motor. The operating software is very similar to the smaller Pyxis so that existing third party software is compatible. De-rotation of the field for long exposure images with alt-azimuth mounted telescope and rotation of the guide chip for SBIG camera to a suitable bright guide star are the two primary uses of this instrument. Power requirements and other operating conditions are similar to the 2-inch Pyxis model.

This model is large and heavy and is intended for larger telescopes on observatory caliber mountings. The 2.4-inch thickness warrants telescopes that can accommodate this increase in the back-focus distance. It uses the same telescope mounts and camera side adapters as the TCF-S3 - Optec's new 3-inch temperature compensating focuser. Any telescope mount or camera side adapter has to be ordered separately.

Cross-sectional view of the Pyxis 3-inch. Click here for a pdf version.
Like the 2-inch Pyxis model, the unit can only be controlled by a PC computer running the Optec PYXIS.exe control software or third party compatible software. Manual control is not possible. A flat wire serial cable is available for connection to a standard RS-232 interface COM port at 19.2K baud. Standard lengths and custom lengths up to 100 feet are possible. Cables and COM port adapters need to be ordered separately. A 15 VDC regulated power supply is included with a right angle 2.5 mm power jack. Stepping up to 15 volts DC provides about 20% more torque without sacrificing speed. Contact Optec to upgrade to the 15 VDC right angle power supply for your existing Pyxis 3-inch.


Optec Pyxis 2" Rotator

The Pyxis camera rotator was especially designed with the guiding chip of the SBIG ST-x CCD cameras in mind. Simply locate a suitable guide star, enter the position angle and let the Pyxis rotate the camera so that a bright guide star is centered on the tracking chip. For those with alt-azimuth mounts, the Pyxis can de-rotate the field while tracking an object. A simple Windows interface program is provided which provides both position angle rotation and de-rotation control modes. The control software is free and updates are also free.

Utilizing a precision sealed 50mm bearing, the Pyxis provides the rigidity and stability you have come to expect from Optec instruments. Weighing under 2 lbs the Pyxis can support and rotate the SBIG ST line of cameras without slipping. If the holding torque of 27 inch-pounds (3 Nm) is exceeded, the drive gear will slip but no damage to the Pyxis will occur. The running torque is 9 inch-pounds (about 1.0 Nm). This limit to the holding and running torque will also prevent damage to cables and instruments if a rotational stoppage does occur. The Pyxis can handle the SBIG AO-7 adaptive optic with camera. The clear aperture of the Pyxis is 1.65 inches and adds about 1.6 inches to the back-focus. For large instrument packages or systems that use the SBIG STL camera with large CCD, the new Pyxis 3-inch model is suggested.

Intelligent firmware will choose the best direction for each move to keep camera cables from binding. The built-in circuit board provides all the control needed - no external hand control box is required. Windows control software is provided with the Pyxis and software integrators will appreciate the simple command language allowing them to easily select a new position angle or activate the derotation control for alt-azimuth tracking.

The Pyxis was designed for use with the Optec TCF-S Focuser and IFW Filter Wheel. Fully compatible with the Optec NextGen MAXfield and NextGen WideField telecompressors the Pyxis can be used at 1X, 0.5X, and 0.33X using any SBIG camera. However, the NextGen telecompressors used with the Pyxis are not compatible with the SBIG cameras having an attached CFW-8/9/10 filter wheel. In this case the back-focus distance for the NextGEN reducer is exceeded.

New Firmware And Circuit Board Available

New firmware is available for the Pyxis 2-inch and 3-inch models. It was suggested that the unit have the ability to adjust the HOME or 0 position angle by software means instead of physically rotating the unit. Seeing the wisdom of this, the firmware has been modified to allow the user to set 0 PA within +/- 15 degrees of the default position. Cost is $25.00. New control software version 1.30 must be downloaded to make use of this new command. This firmware is only compatible with Rev. 1 circuit boards for the Pyxis 2-inch. Earlier models require a circuit board replacement.

Optec Pyxis LE Rotator

The NEW Optec Pyxis LE is a low profile, lightweight, and versatile Camera Field Rotator with standard mechanical interfaces for ease of connectivity. Based on a design by Ted Agos of the Acorn Hollow Observatory, the Pyxis LE is the thinnest camera field rotator available today!

The telescope side of the Pyxis LE is a simple two-inch "push-fit" barrel. The long barrel adapter, just short of 2-1/2 inches, is easily inserted into any 2" focuser such as the Optec TCF-S Temperature Compensating Focuser. Combined with the TCF-S or TCF-Si, the Pyxis LE creates a focuser/rotator combination requiring less than 4-1/2 inches of back-focus.

The camera side of the Pyxis LE is a standard male T-thread. Any T-thread camera, filter wheel, off-axis guider, or industry standard T2 ring can screw directly on to the exit port of the Pyxis LE - no other adapters are required. All of the users existing accessories - T-thread spacers, off-axis guiders, filter wheels, etc. - can be attached directly. With the Pyxis LE, the confusion typically surrounding adapters is eliminated since the Pyxis LE is ready to use out-of-the-box. Simply attach your camera, slip into a 2-inch focuser, and you're ready to go.

The Pyxis LE is ideally suited for small, well-balanced cameras such as the QSI, Fish Camp, Starlight Xpress or SBIG ST-series CCD cameras. Canon and Nikon DLSR cameras will attach directly using an optional T2 bayonet ring. Optional T-thread extender rings can be added in 7.5 and 15mm lengths for additional offset to avoid filter wheel stepper motors such as with the SBIG CFW9.


Physical Size: 3.14" x 4" x 6.5" (80mm x 102mm x 165mm)
Clear aperture: 1.515" (38.5mm)
Weight: approx. 1.1 lb. (.5 kg)
Telescope Adapter: 2" barrel adapter for any 2" focuser
Camera Adapter: T-thread
Back-Focus: .68" (17.3mm)
Resolution: 0.050 degrees/step
Power: 12 VDC 1 Amp (12 Watts max)
Communications Interface: USB 2.0
Software Interface: Pyxis LE-Control and ASCOM-compliant driver
f/6.3 Telecompressor Optics Integration

Pyxis LE f/6.3 Spacing DiagramThe Pyxis LE can also accommodate Schmidt-Cassegrain f/6.3 optics (or any 43mm diameter optical system) without adding additional back-focus. The f/6.3 telecompressors available from Celestron, Meade, Antares and Hirsch fit directly into the 2-inch nosepiece of the Pyxis LE. The optics must first be removed from their original housing and then using a pair of optional retainers the optical elements can be inserted anywhere within the 2" barrel of the rotator. Optec technicians will install customer supplied lenses for a nominal fee. This feature is essential when setting critical telecompressor or field flattener spacing to the imaging sensor. It should also be noted that the optics rotate with the camera so additional flat-fields are usually not required for different position angles. Click the drawing above or here to view the Pyxis LE f/6.3 spacer diagram cut-away.

Cutaway of the Pyxis LEThe mechanical design is exceptionally robust and rigid. The Pyxis LE's rigidity is due to two coaxial thrust bearings that provide support for small to medium sized instrument loads (2.5kg or 5.5 lbs. maximum). The large separation distance between bearing surfaces (2.28") further increases the stability of the Pyxis LE. This permits off-axis guiders, filter wheels, AO units and of course, the CCD camera, to be attached with no flexure. This unique bearing arrangement allows the rotator to be very thin and use only 0.68" of back-focus.

Interface Software and ASCOM Driver

Interfacing with the computer is also extremely simple. Just plug in the USB and 12VDC cables, let Windows install the drivers automatically, open up Pyxis-LE Control, watch it automatically connect, and start using your rotator. Additionally, the Pyxis LE is ASCOM compliant so it can be used in programs like Maxim DL. Intelligent anti-cable wrapping is programmed at the firmware level so you can expect a non-binding experience with both the control program and the ASCOM driver.

Easy to use Windows application allows simple control over your Pyxis LE camera field rotator.

Graphical position indicator allows for quick adjustments and instantaneous position feedback.

The View menu enables users to hide/show certain regions of the application to reduce overall window clutter.

Pyxis LE Downloads

Click here for exploded Diagram

Video - Ted Agos explainshow to remove the Celestron f/6.3 optics from the original SCT threaded cell.

Technical Specs:

Optional Accessories include

#19631 Pyxis LE Retainer Kit for 43mm optics.

#19850 T-thread to SCT thread Expansion Ring.