Description
Rich Simons of Deep Sky Instruments and Optec have jointly developed a new, larger diameter standard spacer for large aperture telescopes. Like the Astro-Physics 2.7-inch spacer set, the Optec-DSI 3.5-inch spacers are available in a five different lengths.
The AP 2.7-inch thread has become an astronomy industry standard thanks to the tireless efforts of Roland and his team at Astro-Physics. Optec has produced a complementary extension set and a few new adapters in an effort to extend this industry standard. However, there are times when the 2.5" clear aperture of the AP2.7 spacers will not allow enough light through clipping the edge rays.
Optec-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" (6.35mm) increments using a minimum number of pieces.
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.
Specifications
- Spacer Lengths Available: 1/2", 3/4", 1", 1-1/2", and 3"
- Clear Aperture: 3.25" (82.5mm)
- Back-focus Usage: Variable (see TABLE below)
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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Stock #19896 DSI 3.5x24tpi to AstroPhysics 2.7" female Adapter
| No Picture Available |
| Stock #19897 DSI 3.5 Retaining Ring
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Target Extension | Spacers Required | AP2.7 Spacer Stock Numbers | DSI 3.5x24 Stock Numbers |
0.50” | ½” | 19882 | 19891 |
0.75” | ¾” | 19883 | 19892 |
1.00” | 1” | 19884 | 19893 |
1.25” | ½” + ¾” | 19882, 19883 | 19891, 19892 |
1.50” | 1-½” | 19885 | 19894 |
1.75” | 1” + ¾” | 19884, 19883 | 19893, 19892 |
2.00” | 1-½” + ½” | 19885, 19882 | 19894, 19891 |
2.25” | 1-½” + ¾” | 19885, 19883 | 19894, 19892 |
2.50” | 1-½” + 1” | 19885, 19884 | 19894, 19893 |
2.75” | 1-½” + ¾” + ½” | 19885, 19883, 19882 | 19894, 19892, 19891 |
3.00” | 3” | 19886 | 19895 |
3.25” | 1-½” + 1” + ¾” | 19885, 19884, 19883 | 19894, 19893, 19892 |
3.50” | 3” + ½” | 19886, 19882 | 19895, 19891 |
3.75” | 3” + ¾” | 19886, 19883 | 19895, 19892 |
4.00” | 3” + 1” | 19886, 19884 | 19895, 19893 |
4.25” | 3” + ¾” + ½” | 19886, 19883, 19882 | 19895, 19892, 19891 |
4.50” | 3” + 1-½” | 19886, 19885 | 19895, 19894 |
4.75” | 3” + 1” + ¾” | 19886, 19884, 19883 | 19895, 19893, 19892 |
5.00” | 3” + 1-½” + ½” | 19886, 19885, 19882 | 19895, 19894, 19891 |
5.25” | 3” + 1” + ¾” + ½” | 19886, 19885, 19883, 19882 | 19895, 19893, 19892, 19891 |
5.50” | 3” + 1-½” + 1” | 19886, 19885, 19884 | 19895, 19894, 19893 |
For all orders exceeding a value of 100USD shipping is offered for free.
Returns will be accepted for up to 10 days of Customer’s receipt or tracking number on unworn items. You, as a Customer, are obliged to inform us via email before you return the item.
Otherwise, standard shipping charges apply. Check out our delivery Terms & Conditions for more details.
