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Solve Focuser Travel Issues with the Tele Vue 2" Barrel Extension
The Tele Vue 2" Eyepiece Barrel Extension (EBX-2120) is a precision-machined component designed for a single, critical task: solving the problem of insufficient focuser out-travel. When your telescope's focuser cannot extend far enough to bring an eyepiece to a sharp focus, this extension provides the 1.2 inches of additional path length needed to achieve a perfect image. It is an essential tool for observers who use a variety of eyepieces.
Achieve Focus Where It Was Previously Impossible
Certain eyepiece designs, particularly those with focal planes deep inside their barrels, may require more outward travel than your telescope's focuser can provide. This is a common scenario in Newtonian reflectors and some refractors when switching between different accessory families. The EBX-2120 provides a fixed, rigid 1.2" (30.5mm) of extension, bridging that gap and bringing otherwise unusable eyepieces into sharp, clear view across the entire field.
Threads Directly onto Your Eyepiece
The EBX-2120 has no clamp or set screw. Its male thread screws into the filter threads at the bottom of a Tele Vue 2" eyepiece, or of the 2" section of a Tele Vue dual-barrel eyepiece, and extends that eyepiece's 2" barrel by 1.2". On a dual-barrel eyepiece, remove the lock screw in the 2" section first.
A Rigid, Threaded Connection
Because it threads onto the eyepiece instead of clamping it, the extension and eyepiece form one rigid 2" barrel that your focuser or diagonal holds like any 2" eyepiece.
Integrate Filters Seamlessly into Your Optical Path
Adding an extension to your setup shouldn't complicate your workflow for using filters. The base of the EBX-2120 is threaded to accept standard 2" (48mm) astronomy filters. This allows you to add a nebula, light pollution, or color filter to the optical train without needing a separate filter cell or changing the spacing you have carefully established, keeping your setup simple and efficient.
From Frustration to Perfect Focus
Imagine you are hunting for the Veil Nebula, and you insert a low-power, wide-field eyepiece to frame the view. You turn the focus knob outwards, and it hits its physical stop just before the stars snap into focus. Instead of a night of compromise, you thread the Tele Vue Barrel Extension onto the eyepiece. The focuser now has ample range, and with a small adjustment, the faint, ghostly filaments of the nebula resolve into sharp, delicate threads against a dark background, turning a moment of frustration into a successful observation.
An Essential and Targeted Solution
While this component is a definitive solution for a known spacing issue, its fixed length is its primary trade-off. It is not designed to be a variable or tunable extender for complex imaging trains where precise, unknown back-focus distances must be dialed in. The EBX-2120 is for the observer who knows they need about an inch of extra travel to make their favorite eyepiece work perfectly with their telescope.
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When do I actually need an eyepiece extension tube?
You need an extension tube when your telescope's focuser runs out of outward travel before your eyepiece can reach focus. This often happens in Newtonian reflectors with low-profile focusers or when using certain eyepieces or accessories that have a long inward focal position.
Will the Tele Vue extension cause my eyepiece to tilt?
No. It threads onto the eyepiece's filter threads, so the eyepiece and extension form one rigid barrel that your focuser or diagonal clamps as usual.
How is this better than just not pushing my eyepiece in all the way?
Leaving an eyepiece partially seated in the focuser creates a sloppy, insecure connection that is prone to tilting and can easily fall out. The EBX-2120 provides a solid, rigid, and perfectly aligned extension of the eyepiece barrel for a secure and optically precise setup.
Can I use 2" filters with the EBX-2120?
Yes, the bottom of the extension tube is threaded to accept standard 48mm filters, commonly known as 2" filters. You can attach your filter directly to the extension before inserting it into the focuser.
Will this work for imaging with my DSLR or planetary camera?
No. The EBX-2120 is made to thread into the filter threads at the bottom of Tele Vue 2" eyepieces, not onto a camera.
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| Product Number |
EBX-2120 |
| Barrel Size |
2" |
| Extension Length |
1.2" (30.5mm) |
| Clamping Mechanism |
None; threads into the filter threads of Tele Vue 2" eyepieces |
| Filter Threads |
48mm (for 2" filters) |
| Material |
Black Anodized Aluminum |
| Kind |
Barrel extension |
| Camera-side connection |
M48x0.75 Male (into eyepiece filter threads) |
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Tele Vue 2" Eyepiece Barrel Extension
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Tele Vue 5-Year Limited Warranty
