DSI 3.5-inch Telescope Adapters
3.5" x 24tpi Threaded Extension Rings
Telescope Adapters and Extensions for the DSI 3.5-inch thread
Extensions, Adapters and Retaining Rings
Rich Simons of Deep Sky Instruments and Optec have developed a new, larger diameter standard spacer large aperture telescopes. Like the Astro-Physics 2.7-inch spacer set, the DSI 3.5-inch spacers are available in a five different lengths. for inch thread has become an astronomy industry standard thanks to the tireless efforts of Roland and his team at Astro-Physics. Optec has produced an extension set and a few new adapters in an effort to extend this industry standard.
Optec's DSI 3.5-inch extension tubes feature female threads on one end with male
threads on the opposite end
with knurled bases to help attach and detach
these tubes. The extensions can be combined and stacked. We
believe our four and five piece sets will provide all the needed
extension for fixed focal length telescopes with 1/4" (12.7mm)
increments using a minimum number of pieces. Click
here for a table of the optimized spacer combinations.
All extensions and mounts are made from high strength 6061 aluminum alloy and black anodized. Anti-reflection threading and internal baffles on the largest extension tube help minimize internal reflections. All internal surfaces are painted and baked with a non-reflecting ultra-flat black paint.
- Spacer Lengths Available: 1/2", 3/4", 1", 1-1/2", and 3"
- Clear Aperture: 2.52" (64mm)
- Back-focus Usage: Variable (see TABLE)
Extension Tube Sets
| Stock #19889 DSI 3.5 Extension Tube Set, 4-piece set
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| Stock #19890 DSI 3.5 Extension Tube Set, 5-piece set
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Individual Extension Tubes and Retainers
| Stock #19891 DSI 3.5 Extension - 1/2" Length
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| Stock #19892 DSI 3.5 Extension - 3/4" Length
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| Stock #19893 DSI 3.5 Extension - 1" Length
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| Stock #19894 DSI 3.5 Extension - 1-1/2" Length
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| Stock #19895 DSI 3.5 Extension - 3" Length
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