Binorum Advanced 9mm 66° FMC 1.25″ Eyepiece
The Universal Star of the Advanced Series
The Binorum Advanced 9mm eyepiece represents the universal centerpiece of the series with the best price-to-performance ratio. The 9mm focal length offers an ideal compromise between magnification and field of view, making this eyepiece perhaps the most versatile in the entire Advanced line. The super wide-angle design with a 66° field combined with medium-high magnification covers the broadest spectrum of observing scenarios - from detailed planetary study to bright deep-sky objects.
Advanced Series - Unbeatable Performance-to-Price Ratio
The entire Binorum Advanced line is designed as the best value choice on the astronomical eyepiece market. These super wide-angle eyepieces provide professional features at prices accessible even to beginning astronomers. A 66° apparent field that surpasses common Plössl and Erfle eyepieces, five-element optical construction with FMC anti-reflection coatings, and generous eye relief - all at a price that's a fraction of premium brands. The Advanced series thus enables building a complete set of quality wide-angle eyepieces without requiring substantial financial investment.
Wide-Angle 66° View for Immersive Observing Experience
The 66° apparent field provides a dramatically wider view of the sky compared to standard eyepieces. This expanded field of view means not only more comfortable observing (objects remain in the field longer as Earth rotates), but also significantly facilitates finding and tracking objects. For beginners, the wide field proves invaluable when learning sky navigation using star-hopping techniques. For experienced observers, it delivers a more immersive viewing experience that resembles naked-eye viewing more than the traditional "tunnel" of narrow eyepieces.
Advanced Five-Element Optics with Multi-Layer Coatings
Every Advanced eyepiece is built on a sophisticated 5-element optical design using glass lenses. All optical surfaces receive multiple anti-reflection FMC (Fully Multi-Coated) treatments that maximize light transmission and eliminate unwanted reflections. This advanced optical architecture ensures sharp, high-contrast images with accurate color rendition across the entire field of view. The five-element design is specifically optimized for wide-angle applications and provides very good aberration correction right to the field edges - a quality level rarely found in eyepieces in this price category.
Comfortable 15mm Eye Relief
With 15mm of eye relief, this eyepiece provides exceptionally comfortable viewing. This generous distance allows relaxed eye positioning with ample clearance from the lens, dramatically reducing fatigue during long observing nights. For eyeglass wearers, the long eye relief is a critical advantage - you can observe comfortably even while wearing glasses. Even without glasses, you'll appreciate the comfort during extended observing sessions when you don't need to press your eye tightly against the eyepiece.
Technical Specifications
- Focal length: 9mm
- Apparent field of view: 66°
- Eye relief: 15mm
- Barrel diameter: 1.25″ (31.7mm)
- Optical design: 5-element with anti-reflection coatings
- Coatings: FMC (Fully Multi-Coated) on all surfaces
- Optical material: Quality optical glass
- Housing: Robust all-metal construction
- Eyecup: Soft rubber fold-down design
- Filter threads: Standard 1.25″ threads
Universal Medium-High Magnification
The 9mm focal length is perhaps the most universal choice in astronomy. With a 900mm focal length telescope, you achieve a practical 100x magnification - an ideal power for a wide range of objects. With a shorter 600mm telescope, you reach 67x, excellent for brighter star clusters and planetary nebulae. Longer instruments around 1350mm provide 150x, a strong magnification for planetary details under good atmospheric conditions. This versatility makes the 9mm eyepiece an outstanding "workhorse" for the most varied observing programs.
Wide Range of Observing Applications
Thanks to its medium-high magnification, the 9mm Advanced eyepiece handles a surprisingly broad spectrum of objects. For lunar observation, it provides sufficient magnification to resolve individual craters, mountain ranges, and rilles while still displaying a large enough area to follow geological context. On planets, it reveals Jupiter's main cloud belts with turbulence along their boundaries, the Cassini Division in Saturn's rings, and albedo features on Mars. For deep-sky objects, it excels on bright star clusters, planetary nebulae, and compact emission nebulae. The wide 66° field increases usefulness on more extended objects like the Milky Way core or larger star clusters.
Excellent All-Metal Construction
Quality metal construction ensures long lifespan and precision. The metal barrel is precision-machined for tight fit in the focuser without any play - critical for maintaining sharpness especially at higher magnifications. Rigid construction withstands regular use including field transport. The metal housing also helps dissipate heat from the observer's hand, minimizing thermal turbulence affecting the image.
Practical Fold-Down Eyecup
The soft rubber eyecup can be folded down for eyeglass wearers or extended to full position for observers without glasses. The eyecup effectively blocks ambient light from the sides, particularly important when observing from lit locations. It also helps maintain proper and comfortable eye distance from the optics.
Filter Threads for Maximum Flexibility
Standard 1.25″ filter threads enable use of a wide range of astronomical filters. You can add a moon filter to reduce glare when observing the full Moon, color filters to enhance planetary contrast, or UHC/OIII filters for emission nebula observation. This flexibility makes Advanced eyepieces truly universal tools.
Significant Upgrade Over Basic Eyepieces
The 9mm Advanced eyepiece represents a dramatic improvement over typical eyepieces supplied with telescopes. Standard basic eyepieces offer narrow fields of view (40-50°), simpler optics with visible edge aberrations, and short eye relief causing eye fatigue. The Advanced series instead provides a wide 66° field, five-element construction with minimal aberrations, and comfortable 15mm eye relief - professional performance for a fraction of the price of branded wide-angle eyepieces.
Surprisingly Quality Optical Correction
Despite its very favorable price, Advanced eyepieces exhibit impressive optical correction. While inexpensive wide-angle eyepieces often suffer significant image quality degradation toward field edges (astigmatism, coma, distortion), the Advanced series maintains usable sharpness and good contrast practically across the entire field. This results from carefully calculated five-element optical design and quality FMC coatings that minimize aberrations and light losses.
Complete Advanced Range for All Needs
The Binorum Advanced series offers three strategically chosen focal lengths covering key magnification ranges:
- 6mm - high magnification for planetary details and lunar relief at high resolution
- 9mm - universal medium-high magnification ideal for the broadest spectrum of objects
- 15mm - medium magnification for wide-angle Moon views, star clusters, and extended nebulae
These three focal lengths form a balanced set covering practically all observing situations. The differences between individual focal lengths are optimally chosen to ensure usable magnifications without excessive gaps.
Ideal for Various Types of Astronomers
The Binorum Advanced 9mm is suitable for:
- Beginning observers seeking a universal first quality eyepiece
- Advanced astronomers building a wide-angle eyepiece collection on a limited budget
- Observers appreciating wide fields without high investment
- Eyeglass users thanks to the generous 15mm eye relief
- Anyone seeking the best price-to-performance ratio on the market
- Astronomers needing a reliable "workhorse" for most observing programs
Easy Object Location
The wide 66° field of view of the Advanced series dramatically facilitates locating objects on the night sky. The larger displayed area enables more efficient use of star-hopping technique - progressively jumping from one star to the next toward the target object. For beginning observers, this provides invaluable assistance when learning to navigate among constellations and star fields.
Why Choose Binorum Advanced
The Binorum Advanced series represents a revolution in quality wide-angle eyepiece accessibility for the broad astronomical community. It combines advanced optical properties - expansive 66° field of view, sophisticated 5-element optical construction, complete FMC anti-reflection coatings, comfortable long eye relief - with price accessibility that puts these eyepieces in the hands of a wide range of astronomers regardless of budget. While competing super wide-angle eyepieces with comparable specifications commonly cost two to three times as much, the Advanced series provides comparable optical performance at substantially lower cost. Careful optical design ensures minimal aberrations, quality metal construction guarantees long-term reliability, and generous eye relief provides comfort even during marathon observing sessions. For astronomers seeking maximum value for their investment, the Advanced series represents an unbeatable choice - authentically the best price-to-performance ratio on today's astronomical eyepiece market.
