Enhance the magnification capabilities of your telescope with the GSO 2.5× APO Design Barlow Lens, a high-quality optical accessory designed for sharp, high-contrast views of the Moon, planets and double stars. Its three-element, air-spaced optical design and fully multi-coated lenses provide an effective way to achieve higher magnifications while continuing to use your existing eyepieces.

Three-Element APO Optical Design

Unlike conventional two-element Barlow lenses, this GSO model features a three-element, air-spaced apochromatic-style optical design engineered to improve colour correction and image sharpness. It helps minimise chromatic aberration while maintaining good contrast, making it particularly useful for high-magnification lunar and planetary observation.

Fully Multi-Coated Optics

All optical surfaces feature fully multi-coated optics to improve light transmission and reduce unwanted reflections. The blackened lens edges and internally blackened barrel further suppress stray light, helping deliver clean, well-defined images with good contrast when observing bright celestial objects.

Versatile 2.5× Magnification

The 2.5× magnification factor provides a useful middle ground between a conventional 2× Barlow and a more powerful 3× model. It increases the effective focal length of your telescope by a factor of 2.5, allowing you to achieve higher magnifications without investing in additional short-focal-length eyepieces.

For example, a 12mm eyepiece used with this Barlow delivers approximately the same magnification as a 4.8mm eyepiece used on its own.

Precision Mechanical Construction

The Barlow features a compact, all-metal housing designed for durability and reliable performance. Its brass compression ring securely holds the eyepiece while helping prevent scratches to the barrel, making it a practical choice for regular observing sessions. The standard 1.25-inch barrel fits compatible telescope focusers and accessories.

Key Features

• Magnification factor: 2.5×

• Optical design: Three-element, air-spaced APO design

• Barrel diameter: 1.25 inches (31.7mm)

• Clear aperture: 23mm

• Optical coatings: Fully multi-coated

• Stray-light control: Blackened lens edges and internal barrel

• Eyepiece clamping: Brass compression ring

• Construction: Precision-machined metal housing

• Weight: Approximately 107g

Ideal For

• High-magnification lunar and planetary observation

• Viewing fine details on Jupiter, Saturn and the Moon

• Splitting double stars

• Extending the magnification range of existing eyepieces

• Observers seeking improved colour correction compared with basic Barlow designs

The GSO 2.5× APO Design Barlow Lens combines a sophisticated three-element optical system with durable mechanical construction, making it a versatile accessory for astronomers who want to expand their telescope's magnification range while maintaining good image quality.

Note: Actual magnification depends on your telescope's focal length and the eyepiece used. High-magnification performance is also influenced by atmospheric seeing, telescope collimation and thermal equilibrium.