Vixen NPL Ploessl 20mm - a reliable eyepiece for planetary and deep-sky observation
The Vixen NPL Ploessl 20mm eyepiece is part of the popular NPL series, which brings together excellent optical performance and accessible pricing. Built on the classic Ploessl four-element optical design, this eyepiece features fully multi-coated (FMC) optics that maximise light transmission and deliver outstanding contrast across a wide range of celestial targets. Whether you are observing the Moon, planets or deep-sky objects, the image remains sharp, bright and true to detail.
The NPL series has established a strong reputation among amateur astronomers as one of the best value-for-money eyepiece lines currently available. The optical quality is consistent throughout the series, making individual eyepieces easy to pair within the same observing session or binoviewer setup.
Key features
50° apparent field of view
The 20mm focal length combined with a 50° apparent field of view provides a comfortable and spacious view of the sky. This makes it well suited for sweeping star fields, locating extended nebulae and enjoying wide lunar landscapes. At 20mm, the eyepiece also delivers a pleasant exit pupil across a broad range of telescope focal ratios.
Standard 1.25″ filter thread
The eyepiece barrel features a standard 1.25″ filter thread, allowing direct attachment of lunar, planetary and narrowband filters such as UHC or OIII - no adapters required. This makes the Vixen NPL 20mm straightforwardly compatible with the vast majority of telescope focusers and accessories available on the market today.
Universal telescope compatibility
The 1.25″ barrel size is the most widely used standard in amateur astronomy. The Vixen NPL 20mm will fit refractors, reflectors and catadioptric telescopes alike, making it an immediately usable addition to any existing eyepiece collection, regardless of telescope brand or model.
Compact and lightweight design
Despite its solid optical construction, the NPL 20mm is notably lightweight and compact. This is particularly advantageous when using the eyepiece in a binoviewer, where balanced and symmetrical loading of both eyepiece channels is important for comfortable extended sessions. The low weight also avoids upsetting the balance of lighter telescope mounts, which can be a practical concern with heavier eyepiece designs.
Suitable for beginners and experienced observers
The Vixen NPL Ploessl 20mm is a versatile, no-compromise eyepiece that works equally well as a first eyepiece for someone new to astronomy and as part of a seasoned observer's collection. Its optical quality, build reliability and broad compatibility make it a practical everyday choice for visual astronomy.
Ideal for binocular viewing
Thanks to its compact form factor and low weight, the Vixen NPL series is especially recommended for use with binoviewers. Matched pairs of NPL eyepieces provide consistent optical performance across both channels, which is essential for a comfortable binocular viewing experience. Long observing sessions of the Moon or planets become noticeably less fatiguing when both eyes can be used without optical imbalance between the two sides.
Technical specifications
| Parameter |
Value |
| Focal length |
20mm |
| Optical design |
Ploessl (4 elements) |
| Apparent field of view |
50° |
| Barrel diameter |
1.25″ |
| Filter thread |
1.25″ standard |
| Coatings |
Fully multi-coated (FMC) |
| Eye relief |
approx. 15mm |
| Recommended use |
Planetary, lunar, deep-sky, binoviewer |
About the Vixen NPL series
The Vixen NPL series has been designed to offer dependable optical quality at a price point accessible to a wide range of astronomers. All eyepieces in the series share the same optical philosophy: clean, contrasty images with minimal aberrations and reliable mechanical quality. The NPL line is a practical choice for observers who want predictable, consistent performance without investing in high-end specialist eyepieces for every focal length in their collection.
