Explore Scientific AR 40mm 68° 2″ eyepiece
If you are looking for an eyepiece that combines comfortable observing with high contrast and reliable optical protection, the Explore Scientific 68° series wide-angle eyepiece with a 40mm focal length and 68° apparent field of view is exactly what you need. It will literally immerse you in the universe - whether you are sweeping vast nebulae, exploring open clusters or drifting through the Milky Way. The 68° field of view creates a genuine sense of immersion that every visual observer will appreciate.
Optical design
The optical system consists of 6 lenses arranged in 4 groups in an SWA (Super Wide Angle) configuration. Every air-to-glass surface is treated with a 15-layer Enhanced Multi-Layer Deposition (EMD™) coating - significantly more layers than most competing products offer. The result is minimal light reflection, outstanding transmission and, above all, high contrast across the entire field of view, free from unwanted ghosting or parasitic reflections. All lens edges are blackened to eliminate stray light inside the eyepiece barrel. The computer-optimised optical design ensures a flat field and precise image correction right to the very edge - something that is by no means guaranteed in wide-angle eyepieces.
Argon purging - superior protection against moisture and dust
One of the key innovations of the 68° series is the use of argon as the inert gas for sealing the eyepiece body, instead of the more commonly used nitrogen. Why argon? Simply because its molecules are larger and therefore diffuse through seals more slowly - keeping the eyepiece hermetically sealed for longer and across a wider range of temperatures. This is particularly important during nights with large temperature swings or when observing in demanding climatic conditions. The waterproof, argon-filled eyepiece reliably protects the optics against moisture and dust throughout the instrument's lifetime.
Comfort and practical details
A long eye relief of 31mm is one of the greatest strengths of this eyepiece. Observers who wear glasses will appreciate being able to see the entire field of view comfortably, without pressing their eye close to the eyepiece. The fold-down eyecup allows quick adjustment for observing both with and without glasses. A filter thread is included as standard, so attaching astronomical filters is straightforward and without compromise.
Key features at a glance
- Focal length: 40mm
- Apparent field of view: 68°
- Barrel diameter: 2″
- Optical design: SWA - 6 lenses in 4 groups
- Coatings: 15-layer EMD™ on all air-to-glass surfaces
- Eye relief: 31mm
- Purging: argon
- Waterproof: yes
- Fold-down eyecup: yes
- Filter thread: yes (standard)
- Blackened lens edges: yes
Why choose Explore Scientific 68°?
Explore Scientific 68° series eyepieces are the result of a meticulous engineering approach that uncompromisingly combines modern coating technology, precision optical design and practical construction details. The Explore Scientific brand has earned worldwide trust among amateur and semi-professional astronomers thanks to its consistent quality and innovative solutions - such as argon purging and 15-layer EMD coatings that are difficult for competitors to match. Whether you are planning long observing sessions, studying fine detail visually or simply want to get the most out of your telescope, the Explore Scientific 68° 40mm will not disappoint.
