Explore Scientific 5X Focal Extender - 1.25"

5X Power: A Major Leap in Magnification

A 5X power increase provides the high magnification needed to resolve fine details on planetary surfaces, split tight double stars, and examine the structure of small planetary nebulae. This focal extender effectively adds a new, very high-power option for every eyepiece you own, expanding your observing capabilities without requiring a whole new set of dedicated high-magnification eyepieces.

This significant boost in magnification will result in a dimmer image, a necessary trade-off for increased image scale. For this reason, the 5X Focal Extender performs best on bright targets like the Moon, Jupiter, Saturn, and Mars, where light grasp is plentiful.

Telecentric Design: Consistent 5X Magnification for Imaging & Visual

Unlike a traditional Barlow lens, the Explore Scientific Focal Extender uses a telecentric design. This multi-element system ensures light rays exit the extender parallel to the optical axis, which results in a fixed, true-to-spec magnification factor regardless of the distance between the extender and the eyepiece or camera sensor.

This consistency is critical for astrophotography. Whether you add a filter wheel or an off-axis guider, the image scale remains a predictable 5X. For visual observers, this design contributes to sharp performance across the entire field of view, especially in faster telescopes.

Preserving Eye Relief: High Power Without the Discomfort

High-power eyepieces are notoriously difficult to look through, often featuring very short eye relief that forces you to press your eye against the lens. The 5X Focal Extender solves this problem by allowing you to use your comfortable, long-eye-relief, low-power eyepieces for high-magnification views.

You can insert a 25mm Plössl with 15mm of eye relief and get the power of a 5mm eyepiece while retaining that comfortable 15mm of eye relief. This is a significant advantage for all observers and is especially beneficial for those who wear glasses.

Focal Extender vs. Traditional Barlow Lens: Why Telecentric Matters

While a conventional Barlow lens is a simple and effective way to increase magnification, its performance is variable. A Barlow's magnification factor changes depending on its distance from the eyepiece, making it difficult to achieve a precise, repeatable image scale. The telecentric Focal Extender, by contrast, delivers a constant 5X magnification factor.

• Predictable Magnification: The extender's 5X power is fixed, which is essential for calculating image scales in planetary imaging setups.
• Improved Edge Correction: The parallel light rays from the telecentric design often result in sharper star images at the edge of the field compared to a simple Barlow, particularly in telescopes with fast focal ratios.
• Maintained Eye Relief: The Focal Extender is explicitly designed to preserve the eye relief of the eyepiece it's paired with, a feature not always prioritized in standard Barlow designs.