Binorum Planetary Pro 6mm 58° 1.25″ Planetary Eyepiece
The Binorum Planetary Pro eyepiece series represents a sophisticated optical solution for demanding planetary and lunar observers. The 6mm focal length model combines a generous 58° apparent field of view with exceptional contrast and sharpness, delivering performance that rivals traditional orthoscopic and premium Plössl designs while offering superior viewing comfort.
Advanced Six-Element Optical Design
At the heart of the Planetary Pro 6mm lies a carefully optimized six-element optical formula that balances field width with on-axis performance. Unlike simpler four-element designs or complex wide-angle eyepieces with nine or more elements, this configuration achieves an ideal compromise - providing a comfortable 58° apparent field of view without the contrast loss, scattered light, or lateral color aberration that plague many wide-field designs.
The optical system delivers razor-sharp images across the entire field, with particular excellence on-axis where planetary detail is most critical. Each air-to-glass surface features broadband multi-layer anti-reflection coatings, maximizing light transmission and ensuring that subtle details on the Moon and planets appear with crisp, high-contrast clarity.
Exceptional Eye Relief for Comfortable Viewing
One distinguishing feature of the Planetary Pro series is the surprisingly long eye relief relative to the short focal length. While many 6mm eyepieces force observers to press their eye uncomfortably close to the lens, the Planetary Pro provides generous eye relief that accommodates extended viewing sessions and allows comfortable use with eyeglasses. The adjustable threaded rubber eyeguard can be raised or lowered to precisely match your preferred eye position, and folds down smoothly for eyeglass wearers.
This extended eye relief virtually eliminates the "kidney-beaning" effect - that annoying black shadow that appears when you shift your head position slightly with short eye relief eyepieces. The result is a more forgiving, comfortable viewing experience even during long planetary imaging sessions or detailed lunar sketching work.
Optimized Internal Construction
Every internal surface has been engineered to suppress stray light and internal reflections. The eyepiece barrel interior features complete blackening treatment, while all internal baffles incorporate anti-reflection micro-edges and full-surface black anodization to minimize light scatter. The lens edges are carefully blackened to prevent reflections that could reduce contrast when viewing bright objects like the Moon or planets.
This meticulous attention to stray light control ensures that when you observe Jupiter's delicate cloud bands or Saturn's subtle atmospheric features, you're seeing detail as nature presents it - not washed out by internal glare or ghost reflections.
Versatile Applications
While optimized for planetary and lunar observation, the Planetary Pro 6mm excels across a broad range of astronomical targets:
- Lunar observation: Reveals intricate crater detail, rilles, and mountain shadows with exceptional clarity. The 6mm focal length provides high magnification ideal for exploring specific lunar features.
- Planetary viewing: Perfect for observing Jupiter's Great Red Spot and cloud belts, Saturn's rings and Cassini Division, Mars' polar caps and surface markings, and Venus' phases. The high contrast is particularly valuable when atmospheric seeing conditions are less than perfect.
- Double stars: The combination of high magnification and sharp optics makes this eyepiece excellent for splitting close binary systems and resolving color contrasts.
- Deep-sky objects: Planetary nebulae, globular clusters, and small galaxies benefit from the higher magnification, while the 58° field provides enough context to appreciate the surrounding star field.
- Projection photography: Suitable for afocal projection methods with DSLR cameras or compact digital cameras for lunar and planetary imaging.
Premium Construction and Features
The mechanical construction reflects the same quality as the optics. The 1.25-inch barrel features a safety undercut groove that prevents the eyepiece from accidentally sliding out of the focuser or diagonal. The barrel accepts standard 1.25-inch astronomy filters via the threaded filter ring, allowing you to enhance planetary contrast with color filters or protect your vision during solar observing with appropriate solar filters.
The flexible rubber eyeguard provides a comfortable viewing position while blocking stray light from entering your eye from the side, improving contrast in brightly lit observing environments. Protective dust caps for both ends of the eyepiece are included to keep the optics clean during storage and transport.
Technical Specifications
- Focal length: 6mm
- Apparent field of view: 58°
- Barrel diameter: 1.25 inches (31.7mm)
- Optical design: Six-element formula
- Coatings: Broadband multi-layer anti-reflection on all air-to-glass surfaces
- Eye relief: Long (comfortable for eyeglass wearers)
- Filter threads: Yes, 1.25-inch standard
- Eyeguard: Threaded rubber fold-down design
- Internal baffling: Full blackening with anti-reflection treatment
- Field stop: Precision machined with black anodization
Calculating Magnification
To determine the magnification this eyepiece will provide with your telescope, divide your telescope's focal length by 6mm. For example:
- 600mm focal length telescope: 600 ÷ 6 = 100x magnification
- 1000mm focal length telescope: 1000 ÷ 6 = 167x magnification
- 1200mm focal length telescope: 1200 ÷ 6 = 200x magnification
For planetary observation, magnifications between 150x and 300x are typically most useful, depending on your telescope's aperture and atmospheric conditions. As a general guideline, useful magnification rarely exceeds 50x per inch of aperture under good seeing conditions.
Why Choose Binorum
Binorum has established itself as a trusted name in amateur astronomy through a commitment to delivering professional-grade optical performance at accessible prices. The Planetary Pro eyepiece series exemplifies this philosophy, incorporating design elements and manufacturing precision typically found only in eyepieces costing significantly more. Each Binorum eyepiece undergoes rigorous quality control testing to ensure it meets exacting optical standards. The brand's focus on practical astronomy means features are chosen for real-world performance rather than marketing specifications - long eye relief, effective stray light control, and durable construction that withstands regular use in the field. When you choose Binorum, you're selecting optics designed by astronomers for astronomers, backed by a reputation built on consistent quality and value.
