Binorum Plössl 20mm 50° 1.25″ Eyepiece
Time-Proven Design for Modern Astronomers
The design of Plössl-type eyepieces has been a favorite among amateur astronomers for decades. Their strength lies in a simple yet ingenious construction that delivers outstanding optical performance. These eyepieces consist of only 4 optical elements, offering a clear and highly contrasting image that experienced observers have come to rely on. We believe this is one of the best eyepieces in this price category, combining proven optical design with modern manufacturing quality.
Key Features and Advantages
- Rubber eyecups protect against scattered light from the sides, ensuring comfortable viewing sessions and preventing stray light from degrading image contrast
- Thanks to anti-reflection coating on all lens surfaces, you see objects bright and clear with minimal light loss
- 1.25″ barrel connector - fits every modern telescope with standard focuser
- Long lifespan - quality-manufactured all-metal construction ensures durability for years of astronomical observation
- Filter threads - simply screw on a moon or nebula filter and start observing immediately
Excellent Edge Performance Even with Fast Telescopes
These eyepieces are characterized by good edge definition, even when used with "fast" f/5 telescopes. You might know this concept from camera lenses: the lower the f-number, the greater the telescope's light-gathering ability and the "faster" it is. Fast f/5 telescopes are among the most demanding optical systems, yet the Binorum Plössl 20mm maintains sharp, well-corrected views right to the edge of the field.
Technical Specifications
- Focal length: 20mm
- Apparent field of view: 50°
- Barrel diameter: 1.25″ (31.7mm)
- Optical design: 4-element Plössl configuration
- Lens coatings: Fully multi-coated
- Eye relief: Approximately 16mm (comfortable for most observers)
- Filter threads: Standard 1.25″ threads on barrel
- Housing: All-metal construction
- Eyecup: Rubber fold-down design
Versatile Magnification for Multiple Applications
The 20mm focal length makes this eyepiece incredibly versatile. When paired with an 800mm focal length telescope, it delivers 40x magnification - ideal for wide-field views of star clusters, large nebulae, and the full lunar disk. With a 1200mm telescope, you achieve 60x magnification, perfect for detailed lunar observation and planetary viewing. The comfortable eye relief and 50° apparent field of view provide an immersive observing experience without causing eye strain during extended viewing sessions.
Optimal Use Cases
- Wide-field deep-sky observation of open clusters and large nebulae
- Full lunar disk viewing with good detail resolution
- Planetary observation at medium magnifications
- Star-hopping and locating objects before switching to higher magnification
- Comet observation and tracking
- General-purpose medium power eyepiece for any telescope
Compatible with Standard Astronomical Filters
The integrated filter threads allow you to enhance your observations with moon filters to reduce lunar glare, or narrowband filters like UHC or O-III for improved nebula contrast. Simply thread your chosen filter onto the eyepiece barrel for instant improvement in specific observing scenarios.
Why Choose Binorum Eyepieces
Binorum eyepieces represent exceptional value in astronomical optics, combining time-tested optical designs with modern multi-coating technology and precision manufacturing. Each eyepiece undergoes strict quality control to ensure consistent performance across the entire product line. The all-metal construction provides long-term durability, while the fully multi-coated optics deliver maximum light transmission and contrast. Binorum has earned recognition among amateur astronomers for delivering professional-grade optical performance at accessible prices, making quality astronomy equipment available to observers at all experience levels.
