Okulár DO-GSO Plossl 20 mm 1,25 inch

Tired of blurry, low-contrast views through the stock eyepieces that came with your telescope? The DO-GSO Plossl 20mm 1.25" eyepiece replaces them with a classic 4-element optical design and fully multi-coated lenses, delivering crisp, bright images across a generous 52° apparent field. From lunar craters to planetary detail and star clusters, this eyepiece brings out the best in your telescope without breaking the bank.

Who is it for

Amateur astronomers at any level who want a reliable, general-purpose 20mm focal length for medium magnification. It fits any telescope with a standard 1.25" focuser—refractors, reflectors, and catadioptrics alike—making it a versatile addition to your accessory case. If you're tired of squinting through low-quality stock eyepieces, this Plossl offers a noticeable upgrade in sharpness and contrast.

Main features

• Plossl optical design: 4 lens elements in 2 groups for excellent color correction and edge sharpness.
• Fully multi-coated lenses: maximize light transmission and reduce internal reflections.
• 20mm focal length: provides comfortable medium magnification for a wide range of targets.
• 52° apparent field of view: a generous window that makes objects easier to track and enjoy.
• 16mm eye relief: comfortable for most users, including those who wear glasses.
• Foldable rubber eyecup: blocks stray light and positions your eye correctly.
• Anodized aluminum housing: durable, lightweight, and resistant to wear.
• Standard 1.25" filter threads: accept common filters for enhanced viewing.

Specifications

• Optical Design: Plossl
• Focal Length: 20 mm
• Barrel Diameter: 1.25" (31.7 mm)
• Apparent Field of View (AFOV): 52°
• Eye Relief: 16 mm
• Number of Lens Elements: 4 elements in 2 groups
• Lens Coating: Fully Multi-Coated (FMC)
• Filter Threads: Yes, standard 1.25"
• Eyecup Type: Foldable Rubber
• Housing Material: Anodized Aluminum
• Edge Blackening: Yes, internal lens edges
• Optical Glass: High-quality optical glass
• Compatibility: All telescopes with 1.25" focusers
• Application: General purpose observation (lunar, planetary, deep sky)
• Distortion: Low
• Chromatic Aberration: Well-corrected

Tips

To get the most out of this eyepiece, allow your telescope to reach thermal equilibrium with the outdoor temperature before observing. Use the foldable rubber eyecup to block stray light and maintain the correct eye position, especially if you wear glasses. For planetary viewing, pair this 20mm eyepiece with a Barlow lens to increase magnification while preserving eye relief.