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GSO 1.25" 2x "Shorty" Achromatic Barlow Lens with T/T2 Thread # GS2BL-T2

Mfg #: GS2BL-T2
Our Price: $32.95
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Quick Overview

  • GSO's 1.25" 2x achromatic Barlow increases the magnification of each eyepiece and effectively doubles or triples the number of eyepieces at your disposal
  • Full unit increases magnification of eyepiece by 2x
  • Features M42x0.75 T/T2 thread on top for direct attachment to 42mm camera T rings for imaging
  • Barlow element can be separated from main tube and threaded directly into a 1.25" eyepiece for approximately 1.5x increase in magnification
  • Low "shorty" profile maintains a comfortable viewing position
  • Two-element, fully-multicoated lenses with excellent color correction, sharpness, and image brightness

Product Details

GSO's 1.25" 2x "Shorty" achromatic Barlow is an excellent accessory that allows you to effectively double the number of eyepieces in your collection. This barlow uses two-element, fully-multicoated lenses with excellent color correction and sharpness. The lens edges are blackened to maximize image contrast. The body is precision CNC-machined from aluminum and sports a handsome finish.

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 1.25" eyepieces with a standard 1.25" 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 an extension tube for 1.25" eyepieces and accessories.

This version of GSO's 1.25" 2x barlow features a male M42x0.75 T/T2 thread on the top. With this, you can attach this barlow to 42mm camera T rings for imaging applications. Note that this will not work with the wide 48mm T rings.

This versatile barlow can be used in a number of ways:

  • Use entire unit with an eyepiece for 2x magnification
  • Use entire unit with a T ring (not included) and your camera for magnified prime focus imaging. The exact magnification factor will vary depending on the backfocus requirements of your camera
  • Use barlow lens cell only with an eyepiece for 1.5x magnification
  • Use the barlow tube only as a 1.25" 36.8mm extension tube
  • Use the barlow tube only as a 1.25" prime focus adapter (although you will need 36.8mm of back-focus in this mode)

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. 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.

Other Information

  • Country of Manufacture: Taiwan
Size Format 1.25 inch (31.7mm)
Nominal Magnification Factor 2x
Number of Lens Elements 2
Lens Coatings Fully multicoated
Total Length 3.07 inches / 78 mm
Length of Nosepiece 1.65 inches / 42 mm
Outside Length of Upper Body 1.45 inches / 36.8 mm
Insertion Depth 1.38 inches / 35 mm
Max Diameter Excluding Thumbscrew 1.96 inches / 49.7 mm
Clear Aperture 0.88 inches / 22.4 mm
Weight 3.2 oz / 90 g
Barlow Lens Cell Removable Yes
Filter Threads at Bottom of Barlow Cell No
Filter Threads Between Barlow Cell and Tube Yes - 1.25" (M28.5x0.6) Filter Threads
Barrel Type Smooth-sided
Compatible Agena Bolt Case (with Screw Removed) 42x80
Compatible Bolt Case (with Screw Attached) 52x80
Number of Thumbscews 1
Thumbscrew Thread Specification M4x0.7
End Caps (Subject to change without notice) 2
Compression Band/Ring in Eyepiece Holder Yes
Country of Manufacture Taiwan
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