Explore Scientific 9mm 120 Degree 2" Argon Purged Waterproof Eyepiece

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  • Focal Length: 9 mm
  • AFOV: 120 Degrees
  • Barrel Size: 2-inch
  • Eye Relief: 13 mm


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  • Regular price $999.99
  • $849.99
  • You save: $150.00 (15%)

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Explore Scientific 9mm 120 Degree 2" Argon Purged Waterproof Eyepiece

Pushing the boundaries of eyepiece design, Explore Scientific spent years developing the 120-degree eyepiece, adding to it the bonus of an Argon purged interior space ensuring that your investment is immune to the outside environment and your eyepiece never falls victim to a damp night.

Like all Explore Scientific eyepieces, the lens elements of the 120-degree eyepiece are meticulously cleaned and aligned before being installed in their precision machined lens barrels.

Each lens and lens grouping have EMD (Enhanced Multilayer Deposition) Coatings and are edge-blackened to eliminate light scatter and maintain image contrast.

Contrast is further enhanced with baffles that mask and deflect unwanted stray light.

These eyepieces with their enormous apparent field of view give the ultimate panoramic experience and with such a wide field, your eye can truly relax and bring in even the faintest details.

Each 120-degree Series Argon-Purged Waterproof eyepiece is internally sealed and purged with inert, dry Argon gas to prevent internal fogging, to halt the intrusion of fine particulates and fungus, and to maximize the life of the internal coatings. Waterproof eyepieces are easier to clean, and there is no risk of cleaning solution migrating from the top of the lens and seeping around edges to be trapped in between elements.

To make sure, every 120-degree eyepiece is tested by submerging them down to 1 meter of water for 30 minutes. After announcing Explore Scientific's line of telescopes at the Astronomical League Conference in the summer of 2008, they decided to focus on extreme performance, ultra-wide angle eyepiece designs as well. Explore wanted to offer ultra-wide angle designs in popular formats at lower prices. Now more astronomers could experience the benefits of the amazing panoramic views these eyepieces provide.

Each and every Explore Scientific eyepiece is inspected both at the factory and again at their USA facility in California to ensure the highest degree of quality. Final visual and cosmetic inspections where the assembly integrity, cleanliness, and optical performance (including a test for visual image edge consistency) before shipping them to OPT.


OPT Product Number: ES-EPWP12009-01


Dust Caps IncludedYes
Eye Guard IncludedYes
Eye Relief13mm
Eyepiece Special FeatureWaterproof
Field of View120 degrees
Focal Length9mm
Free ShippingYes
ManufacturerExplore Scientific
ModelExplore Scientific 120 degree Waterproof
Optical DesignWide Angle
WarrantyLifetime Warranty


  • Explore Scientific 9 mm 120 Degree Eyepiece


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Dighaye c.
Immense FOV, chromatism

This ambitious eyepiece does not disappoint with its 120° field of view. Images are quite acceptable on axis when used on telescopes as fast as f/4.5. Contrast is fairly high. Towards the edges, lateral color is so pronounced that the spectral type of some objects can be determined (maybe an advantage after all?. Incredible 'spacewalk' effect on star clusters and bright galaxies. Not usable in daylight - when the eye's pupil is small, the whole FOV cannot be seen at once, and there are annoying, changing color hues across the FOV. Rather disappointing on the Moon for the same reason.