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Achieve Perfect Back Focus with the Tele Vue 2.4" Accessory Tube
The Tele Vue 2.4" Accessory Tube - 0.50" (12.7mm) is a precision-machined imaging spacer designed to solve one of astrophotography's most critical challenges: achieving exact back focus. This component is not merely an extension; it is a calibrated tool for building a rigid, perfectly aligned imaging train with your Tele Vue NPis refractor, ensuring your camera sensor sits precisely where the corrected focal plane exists.
The Foundation of a Rock-Solid Imaging Train
At the heart of Tele Vue's imaging system is the proprietary 2.4-inch thread specification. This large-diameter connection provides a significant advantage over standard 2-inch nosepieces or M48 threads by eliminating the potential for tilt and flexure. When you thread the TLC-0500 into your imaging train, you are creating a solid metal-on-metal connection that preserves the perfect optical alignment delivered by your NPis telescope's optics.
Precision Spacing for Critical Back Focus
Modern field flatteners, reducers, and camera sensors have stringent back focus requirements, often specified to within a fraction of a millimeter. The TLC-0500 provides a fixed, repeatable 12.7mm of spacing, allowing you to methodically build out your imaging train to meet that target. By combining different tubes from the 2.4" accessory family, you can dial in your camera's distance with high confidence, a crucial step for achieving sharp, aberration-free stars across the entire frame.
Engineered for Performance and Durability
Each Tele Vue accessory tube is machined from solid aluminum and finished with a durable black anodizing. This process not only protects the component from wear but also provides a non-reflective internal surface to maximize contrast by absorbing stray light. The precision-cut threads ensure smooth, secure engagement, so you can assemble and disassemble your imaging setup in the dark without fumbling or cross-threading.
Limitations and System Context
It is important to understand that this accessory tube is designed exclusively for the Tele Vue 2.4" imaging system ecosystem, primarily for the NP101is and NP127is telescopes. It is not compatible with standard 2-inch focusers or SCT threads. While it provides a fixed extension, it is part of a modular system; achieving your target back focus will likely require combining this tube with other Tele Vue 2.4" spacers of different lengths.
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What is this Tele Vue extension tube used for?
This tube adds exactly 0.50 inches (12.7mm) of spacing to your imaging train. It is used with Tele Vue NPis telescopes to achieve the precise back focus distance required by your specific camera and reducer or flattener combination.
Will this fit a standard 2-inch focuser?
No. This tube uses Tele Vue's proprietary 2.4-inch diameter thread. It is specifically designed for the focusers and imaging system accessories of the Tele Vue NP101is and NP127is telescopes and will not thread into standard 2-inch or M48 accessories.
How do I know which length accessory tube I need?
You must calculate your required back focus by starting with the specification of your flattener or reducer, then subtracting the back focus of your camera and any other accessories like filter wheels. The remaining distance is what you need to fill with a combination of these accessory tubes.
Is this a single component or a set?
This is a single accessory tube, model TLC-0500, that provides 0.50" of extension. Tele Vue offers a range of other lengths, sold separately, to allow for modular and precise spacing adjustments.
Why use this instead of a generic M48 spacer?
The Tele Vue 2.4" system provides a larger, more rigid, and fully illuminated connection that prevents both vignetting and tilt. Using this accessory tube maintains the integrity of the Tele Vue imaging train for optimal performance with their telescopes.
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| Product Code |
TLC-0500 |
| Extension Length |
0.50" (12.7mm) |
| Connection Type |
Tele Vue 2.4" Female to Male Thread |
| Material |
Black Anodized Aluminum |
| Compatibility |
Tele Vue NP101is, NP127is, and other 2.4" Imaging System accessories |
| Weight |
1.9 oz (54 g) |
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2.4" Accessory Tube - 0.50" (12.7mm)
× 1
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Tele Vue 5-Year Limited Warranty
