Optec Inc. Optec-DSI 3.5x24tpi Extension Tube, 3” Length

• Innovative Collaboration: Developed by Deep Sky Instruments and Optec, enhancing telescope capability for large aperture telescopes.
• Industry Standard Enhancement: Complements the Astro-Physics 2.7-inch thread standard, addressing limitations in clear aperture size.
• Optimal Light Passage: Designed to allow more light through by reducing edge ray clipping, improving the overall observation and imaging experience.
• Versatile and Stackable: The 3” extension tube features both female and male threads, allowing for stacking and versatile use with other extension tubes.
• Durable Construction: Made from strong 6061 aluminum alloy, ensuring durability and longevity with a black anodized finish for reduced reflection.
• Minimized Internal Reflections: Features anti-reflection threading and internal baffles to significantly reduce internal light reflections.
• Non-Reflective Interior Coating: All internal surfaces are coated with an ultra-flat black paint to minimize reflection and enhance optical performance.
• Modular Design: Part of a set with varied lengths, this 3" tube is compatible with other Optec-DSI extensions, offering solutions for a range of telescope configurations.
• Enhanced Telescope Compatibility: Ideal for fixed focal length telescopes, providing necessary extension in precise 1/4" (6.35mm) increments.
• Professional Grade Quality: Specially designed for serious astronomers and astrophotographers seeking improved telescope performance and imaging quality.

Specifications

• Overall Height: Varies
• Clear Aperture: 3.25" (82.5mm)
• Weight: 1.0 oz. (30 g)
• Back-focus Usage: 0.50" (12.7mm)
• Drawing
• Table for spacer combinations.