Optec Inc. Optec-DSI 3.5x24tpi Knurled Female Threaded Retaining Ring

• Innovative Joint Development: Created by Deep Sky Instruments and Optec, enhancing functionality for large aperture telescopes.
• Astro-Physics Thread Standard: Adheres to the AP 2.7-inch thread, a benchmark in the astronomy industry established by Astro-Physics.
• Optimal Light Transmission Design: Specifically designed to overcome the light clipping issues of the AP2.7 spacers, offering improved light passage.
• High-Quality Material Construction: Crafted from 6061 aluminum alloy, known for its strength and durability, and finished with a black anodized coating for additional protection.
• Versatile and Stackable Extensions: Features female threads and knurled bases, allowing for easy attachment, detachment, and stacking of extension tubes.
• Precise Length Variations: Part of a versatile set offering critical extensions in 1/4" (6.35mm) increments, catering to fixed focal length telescope requirements.
• Minimized Internal Reflections: Equipped with anti-reflective threading and internal baffles to significantly reduce internal light reflections, optimizing telescope performance.
• Non-Reflective Internal Coating: All internal surfaces are coated with ultra-flat black paint, preventing any reflective disturbances and enhancing image quality.
• Comprehensive Set Options: Available in multiple lengths (including ½”, ¾”, 1", 1-1/2", and 3") for a wide array of spacer combinations, ensuring broad compatibility with various telescope models.
• Robust and Practical Design: The knurled feature on the female threaded retaining ring offers ease of use and secure fitting, making it ideal for astronomers and astrophotographers looking for reliable telescope extensions.

Specifications

• Overall Height: 0.14" (3.5mm)
• Clear Aperture: 3.45" (87mm)
• Weight: 0.4 oz. (15 g)
• Back-focus Usage: 0.10" (2.5mm)
• Anodize: Gold
• Drawing