Explore Scientific 3x focal extender - Barlow lens 1.25″
Looking for a reliable way to significantly increase the magnification of your telescope without compromising image quality? The Explore Scientific 3x focal extender is designed exactly for this purpose. It combines a well-thought-out optical design with high-quality mechanical construction, delivering the full performance of your eyepiece even at triple the focal length.
Telecentric optical design for sharp, high-contrast images
At the heart of this extender is a telecentric design with four optical elements, all featuring fully multi-coated (FMC) anti-reflection surfaces. This ensures maximum light transmission while keeping the image sharp, contrasty, and free from unwanted reflections. All lenses have blackened edges, which eliminates stray light inside the extender body and further improves contrast - something you will especially appreciate when observing planets or the Moon.
Compared to standard Barlow lenses, a telecentric optical system has one key advantage: the output rays are parallel to the optical axis. This means the extender preserves the eye relief of the eyepiece unchanged, making it suitable for binocular viewers or precise eye measurements. The focal length extension factor is a fixed 3x, so calculating the resulting magnification is straightforward and predictable.
Solid metal build and practical features
The Explore Scientific 3x focal extender for 1.25″ eyepieces is equipped with a metal compression ring that holds the eyepiece without direct contact with a metal edge - minimizing the risk of scratching the eyepiece barrel and ensuring centered, play-free attachment. The extender body is fully metal, with a length of 100 mm and a maximum diameter of 48 mm. The weight of 258 g reflects solid build quality rather than unnecessary over-engineering.
The 1.25″ filter thread allows standard astronomical filters to be attached directly to the extender - a practical detail that saves time when working in the field.
Key specifications
| Parameter |
Value |
| Magnification factor |
3x |
| Barrel diameter |
1.25″ |
| Optical elements |
4 (telecentric design) |
| Lens coatings |
FMC (fully multi-coated) |
| Body material |
Metal |
| Body length |
100 mm |
| Maximum diameter |
48 mm |
| Weight |
258 g |
| Filter thread |
1.25″ |
| Eyepiece holder |
Metal compression ring |
Who is this extender for?
This focal extender is a great choice for:
- Experienced observers of planets and double stars who need to flexibly extend the capabilities of their eyepiece collection
- Astrophotographers using cameras at the focuser
- Users of telescopes with a medium focal length, where a standard 2x Barlow lens is not enough, but switching to a shorter focal length eyepiece is not desired
- Anyone using binocular viewers, since the telecentric design preserves the original eye relief of the eyepiece
A smart upgrade without buying a new eyepiece
The telecentric 3x extender from Explore Scientific is exactly the tool that takes your observation to the next level - without the need to invest in a new eyepiece. The fixed 3x factor, FMC-coated optics, and robust all-metal construction make it a reliable and versatile accessory for both visual observation and astrophotography.
