Barlow lens Tele Vue BLW-2125 2× for 1.25-inch eyepieces

Tele Vue BLW-2125 is a 2× Barlow lens engineered for use with 1.25-inch eyepieces. Designed to double the effective focal length of a compatible eyepiece, this compact optical accessory increases magnification for planetary, lunar and deep-sky observing while fitting between the focuser and the eyepiece. The unit is intended to preserve image quality and maintain parfocal characteristics with many eyepieces, providing increased flexibility in framing and higher-resolution views without changing primary optics.

Advantages

The Barlow lens offers a simple way to increase magnification without requiring additional eyepieces. Its 2× power reliably doubles the apparent magnification of compatible 1.25-inch eyepieces while minimizing introduced aberrations. The compact construction keeps the optical path short and maintains mechanical stability in the focuser. Because it is placed between the eyepiece and focuser, the accessory retains the user's existing eyepiece collection and allows quick changes in effective focal length.

Suitable for

• Planetary observing where higher magnification reveals surface detail
• Lunar observing to increase resolution on craters and maria
• Deep-sky targets when additional magnification is needed for small galaxies or planetary nebulae
• Astrophotography setups that use 1.25-inch eyepiece projection or visual back adapters
• Observers who want to extend the usable range of their eyepiece set without buying extra eyepieces

Key specifications

• Magnification factor: 2×
• Designed for eyepieces with 1.25-inch (31.7 mm) barrel diameter
• Compact inline design that mounts between focuser and eyepiece
• Optical construction optimized to preserve image quality and minimize aberrations
• Maintains parfocality with many eyepiece designs

How to use

Insert the Barlow lens into the focuser or visual back, then seat a 1.25-inch eyepiece into the Barlow's eyepiece holder and secure it with the eyepiece clamp. Focus as usual with the telescope focuser; the Barlow doubles the effective focal length so you may need to adjust focus slightly compared with using the eyepiece alone. For parfocal eyepieces, final focus adjustments are typically small. When switching magnifications, remove or install the Barlow while the telescope is pointed safely away from bright light sources.

Usage recommendations

Use the Barlow with eyepieces appropriate for your telescope's aperture and atmospheric seeing conditions; on nights of poor seeing very high effective magnification may reduce image contrast. For best results, pair the 2× Barlow with eyepieces that have good optical correction and sufficient eye relief. Secure mounting and gentle handling will help maintain collimation and image quality.