SVBONY SV137 1.25″ FMC Barlow Lens with Brass Ring

Product Overview

The SVBONY SV137 is a 1.25″ Barlow lens that multiplies the magnification of the eyepiece placed in it — this listing is the 3x version (item W9106D). It uses a fully multi-coated cemented lens group with blackened edges, a CNC-machined aluminium body with matte-painted interior, and an internal brass ring that holds the eyepiece without scratching its barrel. It weighs 96 g and comes with a pair of dust covers.

Who It's For

This is a good match if you observe with 1.25″ eyepieces and want more magnification on the Moon, planets and double stars without buying additional short-focal-length eyepieces. A 3x Barlow effectively triples your eyepiece collection: a 15 mm eyepiece behaves like a 5 mm.

Key Features & Design

• 3x magnification: triples the effective focal length of the telescope.
• Fully multi-coated, cemented lens group: for light transmission and sharpness.
• Blackened lens edges and matte interior: to reduce stray light and reflections.
• Internal brass ring: clamps the eyepiece barrel without marking it.
• Large locking nut and anti-slip ring: quick eyepiece insertion and a secure grip.
• CNC aluminium body, 96 g: light and compact.

Optical Design

A Barlow is a negative lens placed ahead of the focal plane. It lengthens the telescope's effective focal length — here by three times — so every eyepiece gives three times the magnification. Because it also raises the effective focal ratio, it lets longer-focal-length eyepieces with more comfortable eye relief reach planetary magnifications. The SV137's lens group is fully multi-coated and edge-blackened to keep contrast at high power.

Recommended Uses

• Planetary observing: Jupiter's belts, Saturn's rings and Mars at higher power.
• Lunar detail: craters and rilles near the terminator.
• Double stars: splitting close pairs.

Compatibility and Accessory Notes

• Eyepieces: fits 1.25″ eyepieces.
• Focuser: inserts into a 1.25″ focuser or diagonal.
• Other versions: SVBONY also lists 2x (W9106A, 90 g), 2x-M42 and bundle versions of the SV137; contact us if you need one of those.

What's in the Box

• SV137 1.25″ 3x Barlow lens
• Pair of dust covers

Good to Know Before You Order

• Magnification has a ceiling: the atmosphere and your telescope's aperture set the useful maximum, so a 3x Barlow works best with medium and longer-focal-length eyepieces.
• 1.25″ only: it does not accept 2″ eyepieces.

Frequently Asked Questions

Is it difficult to set up?

No. Insert the Barlow into your focuser or diagonal, put the eyepiece into the Barlow, tighten the locking nut and refocus.

Which eyepieces work best with a 3x Barlow?

Medium to long focal lengths — roughly 12 mm to 25 mm — give planetary magnifications while keeping comfortable eye relief.

Will it scratch my eyepieces?

The internal brass ring is there to hold eyepiece barrels without marking them.

Can I use it for imaging?

This listing is the 3x version for 1.25″ eyepieces. SVBONY also lists 2x, 2x-M42 and bundle versions; get in touch and we will confirm which suits your setup.

Bottom Line

In short: a 96 g, fully multi-coated 1.25″ 3x Barlow with a brass compression ring — a simple way to triple the magnification of the eyepieces you already own.