GSO's 2" 2x ED Barlow is perhaps the best barlow of its kind on the market today, and one of our perennial best-sellers. This barlow uses two-element, fully-multicoated lenses made from special ED (Extra-Low Dispersion) glass for excellent color correction and sharpness. The lens edges are blackened to maximize image contrast. The clear aperture is 37mm so you can use even 2" wide-angle eyepieces without vignetting.
The body is precision CNC-machined from aluminum and sports a handsome finish that you would usually find on much higher priced items. The barlow comes with a 2"-1.25" adapter so it can be used with 1.25" or 2" eyepieces. The barlow tube and the 1.25" adapter both feature brass compression rings so the set-screw will not scratch your eyepiece barrels.
A really nice feature of this GSO barlow is that the barlow element is housed in a separate metal cell at the bottom that can be unscrewed from the upper tube (see photos). You can then screw the barlow cell directly into 2" eyepieces with a standard 2" filter thread to increase the magnification of that particular eyepiece while still maintaining a low profile. When screwed into an eyepiece, the barlow will yield approximately 1.5x of magnification. So, for example, a 30mm eyepiece can be used with the barlow element screwed on as a 20mm eyepiece, or with the complete barlow as a 15mm eyepiece. That's like having three eyepieces in one! You can also use the tube by itself without the barlow element as a 27mm (1.1") extension tube for 2" eyepieces and accessories.
Note that the use of any optical element like barlows and focal reducers changes the focus point of your telescope, requiring additional in-focus or out-focus travel. This GSO 2" 2x ED barlow will require at least 19mm (0.75") or more of additional in-focus travel. The exact amount of focus travel required will depend on the optics and mechanics of your specific set-up (telescope, diagonal (if used), barlow, and eyepiece). Hence, be aware that you may not be able to reach focus with all eyepieces or in all configurations with a given barlow.
- Barlow element separates from extension tube and threads directly into a 2" eyepiece for 1.5x increase in magnification
- Two-element, fully-multicoated lenses with excellent color correction, sharpness, and image brightness
- Barrel Size:2 inch (50.8mm)
- Magnification Factor: 2x
- Coatings: Fully multicoated, Blackened lens edges
- Height (Total):116mm
- End Caps: 2
- Other: Includes 2" to 1.25" conversion adapter with brass compression ring