GSO 1.25" 2.5x Apochromatic Barlow Lens # BL251

Our Price: $55.00
Free shipping for this item in the US Click here for more info

Contiguous US Customers:
All items we sell ship for free within the Contiguous US. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. During checkout, you may also be shown other optional faster shipping choices.

US Customers in Hawaii and Alaska:
Free shipping applies to almost all products. A few large telescopes and mounts are excluded from this free shipping offer. For these items, please contact us to obtain a shipping quote before you check out using the online shopping cart.

International Customers:
Free shipping does not apply to international orders. During check-out, you will be presented with several shipping choices and costs. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions.

In Stock (10+ Available)
Ships by Next Business Day
Our Product ID: OBAR-GS-BL251
Manufacturer SKU: BL251
Item Can Ship: Worldwide
GSO 1.25" 2.5x Apochromatic Barlow Lens # BL251

More Views

  • GSO 1.25" 2.5x Apochromatic Barlow Lens # BL251

Quick Overview

  • GSO's 1.25" 2.5x fully apochromatic Barlow increases the magnification of each eyepiece and effectively doubles the number of eyepieces at your disposal
  • Low profile maintains a comfortable viewing position
  • Air-spaced, three-element, fully-multicoated ED lenses with excellent color correction, sharpness, and image brightness
  • Precision-machined aluminum barrel with high-quality black-anodized finish and knurled ring to aid in handling

Product Details

If you need more power than your eyepieces alone can provide, we offer a new apochromatic 2.5x Barlow lens from GSO (Guan Sheng Optical) to give a big magnification boost to any 1.25" eyepiece it's used with.

Nothing has been compromised in GSO's latest and finest offering. This Barlow features an air-spaced, three-element, apo design with fully multicoated optics. The housing is precision machined from aluminum stock and black anodized to a hard finish. The lens edges and inner barrel are blackened to provide maximum contrast. The Barlow body includes a brass compression ring so that your eyepiece barrels are not marred by the captive set screw. The 2.5x model has a clear aperture of 23mm. For those who need a very high quality Barlow for all-round use, the 2.5x barlow is a very nice step up from the typical 2x achromatic barlows commonly found on the market.


  • Barrel size = 1.25" (31.7mm)
  • Magnification factor = 2.5x
  • Weight = 3.5oz (99gm)
  • Total height = 2.95" (75mm)
  • End caps = 2
  • 1.25" filter threads on bottom of barlow: No
  • Made in Taiwan
Manufacturer GSO
Size Format 1.25 inch
Magnification Factor 2.5x
Number of Lens Elements
Lens Coatings Fully multicoated
Total Length 2.95 inches / 75 mm
Length of Nosepiece 1.18 inches / 30 mm
Outside Length of Upper Body 1.8 inches / 45.7 mm
Insertion Depth 1.57 inches / 40 mm
Max Diameter Excluding Thumbscrew 1.92 inches / 48.8 mm
Clear Aperture 0.88 inches / 22.4 mm
Weight 3.5 oz / 99 g
Barlow Lens Cell Removable No
Filter Threads at Bottom of Barlow Cell No
Filter Threads Between Barlow Cell and Tube N/A
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

You May Also Be Interested In...

GSO 1.25" Neutral Density / Moon Filter ND96-0.6 25% Transmission

GSO 1.25" Neutral Density / Moon Filter ND96-0.6 25% Transmission

Our Price: $13.50
GSO 1.25" Plossl Eyepiece - 32mm

GSO 1.25" Plossl Eyepiece - 32mm

Our Price: $36.00
GSO 1.25" Plossl Eyepiece - 15mm

GSO 1.25" Plossl Eyepiece - 15mm

Our Price: $31.00
Agena 1.25" Starguider Dual ED Eyepiece - 12mm

Agena 1.25" Starguider Dual ED Eyepiece - 12mm

Our Price: $60.00