Binorum Kellner 15mm 50° 1.25″ Eyepiece
Classic Optical Design for Reliable Performance
The Kellner eyepiece design has been a trusted choice in amateur astronomy for over a century. This time-proven 3-element optical configuration delivers clear, sharp views of celestial objects at an accessible price point. The Binorum Kellner 15mm represents excellent value for beginners and intermediate observers who want quality optics without breaking the bank.
Versatile 15mm Focal Length
With a focal length of 15mm and a 50° apparent field of view, this eyepiece offers versatile magnification suitable for a wide range of astronomical targets. Whether you're observing lunar craters, planetary details, or brighter deep-sky objects, the Kellner 15mm provides a comfortable viewing experience with adequate magnification for most observing scenarios.
Key Features
- Classic Kellner 3-element optical design for reliable image quality
- 50° apparent field of view provides a comfortable observing experience
- 1.25″ barrel diameter - universal compatibility with all modern telescopes
- Multi-coated optics for improved light transmission and contrast
- Metal barrel construction for durability
- Filter threads for adding moon or color filters
- Rubber eyecup for comfortable viewing and stray light protection
Technical Specifications
- Focal length: 15mm
- Apparent field of view: 50°
- Barrel diameter: 1.25″ (31.7mm)
- Optical design: 3-element Kellner configuration
- Lens coatings: Multi-coated
- Eye relief: Approximately 10-11mm
- Filter threads: Standard 1.25″ threads
- Housing: Metal construction
Ideal Magnification for Multiple Targets
The 15mm focal length strikes an excellent balance between magnification and field of view. With a 750mm focal length telescope, this eyepiece delivers 50x magnification - perfect for detailed lunar observation and scanning the lunar surface for craters and maria. Paired with a 1000mm telescope, you achieve 67x magnification, ideal for planetary observation of Jupiter's cloud bands, Saturn's rings, and Mars during opposition.
Optimal Use Cases
- Detailed lunar crater observation and surface features
- Planetary viewing at medium to high magnification
- Double star separation and observation
- Brighter deep-sky objects including globular clusters
- General-purpose medium-high power observations
- Excellent starter eyepiece for beginners building their collection
Perfect for Beginning and Intermediate Observers
The Kellner design offers an excellent entry point into quality astronomical eyepieces. While not as sophisticated as modern wide-field designs, it provides honest optical performance that has satisfied generations of amateur astronomers. The straightforward 3-element design minimizes internal reflections and delivers good contrast on planets and the Moon.
Compatible with Astronomical Filters
The integrated filter threads allow you to enhance your observations with various accessories. Add a moon filter to reduce glare during bright lunar phases, use planetary color filters to enhance contrast of planetary features, or attach polarizing filters for variable light reduction. The standard 1.25″ threads ensure compatibility with the vast majority of astronomical filters on the market.
Build Quality and Durability
Despite its budget-friendly price point, the Binorum Kellner 15mm features solid metal construction that ensures long-term reliability. The barrel is precisely machined to fit snugly in telescope focusers without wobbling, while the rubber eyecup provides comfortable viewing and helps block stray light from the sides during observation sessions.
Why Choose Binorum Eyepieces
Binorum eyepieces deliver exceptional value by combining proven optical designs with careful manufacturing and quality control standards. Each eyepiece is crafted to provide reliable performance that amateur astronomers can depend on night after night. The multi-coated optics maximize light transmission while the robust metal construction ensures durability for years of astronomical exploration. Binorum has established a strong reputation for making quality astronomy equipment accessible to observers at all levels, from those just starting their journey into amateur astronomy to experienced enthusiasts expanding their eyepiece collection.
