OPTEC Libra Alt-Az Adjustable Mount
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- Precise altitude and azimuth adjustment for easy dual-scope alignment.
- Clamps directly to most standard “D” style dovetail bars.
- No-tools setup with large adjustment knobs and locking thumb nut.
- Designed for more secure, repeatable alignment than guide rings.
OPTEC Libra Alt-Az Adjustable Mount
The Optec Libra Alt-Az Mount makes aligning two co-axial telescopes faster, easier, and far more precise than traditional adjustable guide rings. Instead of juggling multiple screws that can shift out of alignment after the slightest bump, the Libra uses a simple dual-adjustment design with dedicated altitude and azimuth controls for smooth, accurate positioning. A female dovetail receiver clamps directly onto any standard “D” style male dovetail bar for quick installation, while large adjustment knobs and a locking thumb nut allow easy no-tools setup and secure alignment in the field or observatory. It’s a smart upgrade for side-by-side telescope systems, guidescopes, and dual optical tube configurations.
Compatibility
As one engineer famously said, “The great thing about standards is that there are so many to choose from…” That quote applies especially well to astronomy hardware, where true mechanical standards can vary from brand to brand. As Dave Wagner noted in his Cloudy Nights review of the Libra Alt-Az, dovetail systems are a common example.
The widely used “D” style dovetail, originally popularized by Scott Losmandy, is generally described as a 4-inch flat plate machined with a 60° dovetail cutter to approximately 1/4-inch depth. In practice, however, even small changes to that cut depth can create noticeably different profiles. This can lead to poor fits between male and female dovetails—or in some cases, components that do not fit together at all.
To improve compatibility, Optec references a more precise measurement method known as MOW (Measure Over Wires), as defined in the Machinists Handbook. This process uses two standard 3/16-inch (0.1875 in) ground dowel pins placed into opposite sides of the male dovetail, then measured across with calipers or a micrometer.
- Ideal nominal MOW dimension: 3.200 in ± 0.020 in
- Allowed variance: approximately 1 mm
- Based on measurements of dozens of dovetail plates from various manufacturers, most fall within this tolerance range
This means the Libra Alt-Az is designed to work with the majority of properly machined “D” style dovetail plates while promoting a more consistent, secure fit.
Specifications
- D-plate Width: 4.00 in (102 mm)
- Overall Width with knobs: 5-8 in (127-203.2 mm)
- Overall Height (level): 2.3-3.0 in ( 58.4-76.2 mm)
- Overall Length: 12.25 in ( 311.2 mm)
- Clamp Width: 2.5 in (63.5 mm)
- Altitude Adjustment: 4°
- Azimuth Adjustment: 9°
- Clamp Fasteners: 3/4 in knurled aluminum
- Alt-Az Knobs: 1-1/2 in knurled aluminum
- Knob Color: Silver
- Weight: 5 lb (2.7 kg)
- Payload Capacity: 25-lb
- Safety: Two 1/4 in-20 knobs on male dovetail (NEW!)
- Compatibility:
- Optec Libra "D" series dovetail systems
- Losmandy D series dovetail systems
- Celestron dovetail bar
- Farpoint D series dovetails systems
- ADM "D" Series dovetail systems
- Robin Casady's dovetail systems
Other Information
- Country of Manufacture: United States
OPTEC Libra Alt-Az Adjustable Mount
The Optec Libra Alt-Az Mount makes aligning two co-axial telescopes faster, easier, and far more precise than traditional adjustable guide rings. Instead of juggling multiple screws that can shift out of alignment after the slightest bump, the Libra uses a simple dual-adjustment design with dedicated altitude and azimuth controls for smooth, accurate positioning. A female dovetail receiver clamps directly onto any standard “D” style male dovetail bar for quick installation, while large adjustment knobs and a locking thumb nut allow easy no-tools setup and secure alignment in the field or observatory. It’s a smart upgrade for side-by-side telescope systems, guidescopes, and dual optical tube configurations.
Compatibility
As one engineer famously said, “The great thing about standards is that there are so many to choose from…” That quote applies especially well to astronomy hardware, where true mechanical standards can vary from brand to brand. As Dave Wagner noted in his Cloudy Nights review of the Libra Alt-Az, dovetail systems are a common example.
The widely used “D” style dovetail, originally popularized by Scott Losmandy, is generally described as a 4-inch flat plate machined with a 60° dovetail cutter to approximately 1/4-inch depth. In practice, however, even small changes to that cut depth can create noticeably different profiles. This can lead to poor fits between male and female dovetails—or in some cases, components that do not fit together at all.
To improve compatibility, Optec references a more precise measurement method known as MOW (Measure Over Wires), as defined in the Machinists Handbook. This process uses two standard 3/16-inch (0.1875 in) ground dowel pins placed into opposite sides of the male dovetail, then measured across with calipers or a micrometer.
- Ideal nominal MOW dimension: 3.200 in ± 0.020 in
- Allowed variance: approximately 1 mm
- Based on measurements of dozens of dovetail plates from various manufacturers, most fall within this tolerance range
This means the Libra Alt-Az is designed to work with the majority of properly machined “D” style dovetail plates while promoting a more consistent, secure fit.
Specifications
- D-plate Width: 4.00 in (102 mm)
- Overall Width with knobs: 5-8 in (127-203.2 mm)
- Overall Height (level): 2.3-3.0 in ( 58.4-76.2 mm)
- Overall Length: 12.25 in ( 311.2 mm)
- Clamp Width: 2.5 in (63.5 mm)
- Altitude Adjustment: 4°
- Azimuth Adjustment: 9°
- Clamp Fasteners: 3/4 in knurled aluminum
- Alt-Az Knobs: 1-1/2 in knurled aluminum
- Knob Color: Silver
- Weight: 5 lb (2.7 kg)
- Payload Capacity: 25-lb
- Safety: Two 1/4 in-20 knobs on male dovetail (NEW!)
- Compatibility:
- Optec Libra "D" series dovetail systems
- Losmandy D series dovetail systems
- Celestron dovetail bar
- Farpoint D series dovetails systems
- ADM "D" Series dovetail systems
- Robin Casady's dovetail systems
- 1x Optec Libra "D" series dovetail systems
- 1x Losmandy D series dovetail systems
- 1x Celestron dovetail bar
- 1x Farpoint D series dovetails systems
- 1x ADM "D" Series dovetail systems
- 1x Robin Casady's dovetail systems
- Precise altitude and azimuth adjustment for easy dual-scope alignment.
- Clamps directly to most standard “D” style dovetail bars.
- No-tools setup with large adjustment knobs and locking thumb nut.
- Designed for more secure, repeatable alignment than guide rings.
OPTEC Libra Alt-Az Adjustable Mount
The Optec Libra Alt-Az Mount makes aligning two co-axial telescopes faster, easier, and far more precise than traditional adjustable guide rings. Instead of juggling multiple screws that can shift out of alignment after the slightest bump, the Libra uses a simple dual-adjustment design with dedicated altitude and azimuth controls for smooth, accurate positioning. A female dovetail receiver clamps directly onto any standard “D” style male dovetail bar for quick installation, while large adjustment knobs and a locking thumb nut allow easy no-tools setup and secure alignment in the field or observatory. It’s a smart upgrade for side-by-side telescope systems, guidescopes, and dual optical tube configurations.
Compatibility
As one engineer famously said, “The great thing about standards is that there are so many to choose from…” That quote applies especially well to astronomy hardware, where true mechanical standards can vary from brand to brand. As Dave Wagner noted in his Cloudy Nights review of the Libra Alt-Az, dovetail systems are a common example.
The widely used “D” style dovetail, originally popularized by Scott Losmandy, is generally described as a 4-inch flat plate machined with a 60° dovetail cutter to approximately 1/4-inch depth. In practice, however, even small changes to that cut depth can create noticeably different profiles. This can lead to poor fits between male and female dovetails—or in some cases, components that do not fit together at all.
To improve compatibility, Optec references a more precise measurement method known as MOW (Measure Over Wires), as defined in the Machinists Handbook. This process uses two standard 3/16-inch (0.1875 in) ground dowel pins placed into opposite sides of the male dovetail, then measured across with calipers or a micrometer.
- Ideal nominal MOW dimension: 3.200 in ± 0.020 in
- Allowed variance: approximately 1 mm
- Based on measurements of dozens of dovetail plates from various manufacturers, most fall within this tolerance range
This means the Libra Alt-Az is designed to work with the majority of properly machined “D” style dovetail plates while promoting a more consistent, secure fit.
Specifications
- D-plate Width: 4.00 in (102 mm)
- Overall Width with knobs: 5-8 in (127-203.2 mm)
- Overall Height (level): 2.3-3.0 in ( 58.4-76.2 mm)
- Overall Length: 12.25 in ( 311.2 mm)
- Clamp Width: 2.5 in (63.5 mm)
- Altitude Adjustment: 4°
- Azimuth Adjustment: 9°
- Clamp Fasteners: 3/4 in knurled aluminum
- Alt-Az Knobs: 1-1/2 in knurled aluminum
- Knob Color: Silver
- Weight: 5 lb (2.7 kg)
- Payload Capacity: 25-lb
- Safety: Two 1/4 in-20 knobs on male dovetail (NEW!)
- Compatibility:
- Optec Libra "D" series dovetail systems
- Losmandy D series dovetail systems
- Celestron dovetail bar
- Farpoint D series dovetails systems
- ADM "D" Series dovetail systems
- Robin Casady's dovetail systems
Other Information
- Country of Manufacture: United States
- 1x Optec Libra "D" series dovetail systems
- 1x Losmandy D series dovetail systems
- 1x Celestron dovetail bar
- 1x Farpoint D series dovetails systems
- 1x ADM "D" Series dovetail systems
- 1x Robin Casady's dovetail systems
OPTEC Libra Alt-Az Adjustable Mount