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Explore Scientific - 9mm 100° Nitrogen-Purged Waterproof Fully Multi-Coated Eyepiece - 2"

Model#: EP1009-01

Discontinued Product

Manufactured by: Explore Scientific


This is a discontinued item. We recommend the Explore Scientific 9mm 100° Argon Eyepiece as a replacement.


Specifications Focal Length: 9mm  

AFOV: 100 degrees  

Eye Relief: 9mm


Nitrogen-Purged and Waterproof: Internally sealed and purged with inert, dry nitrogen gas to prevent internal fogging, to halt the intrusion of fine particulates and fungus, and to maximize the life of the internal coatings. To make sure, each eyepiece is tested by submerging each unit in 1 meter of water for 30 minutes.

Coatings: All lens-to-air surfaces are fully multi-coated

Eyecups: Soft rubber folding style; Replaceable

Weight: 2 lbs

Explore Scientific 100 Degree Waterproof Eypieces

All 100° Series eyepieces are fully multi-coated and edge-blackened to produce maximum contrast.

Using advanced computer design, combinations of low dispersion and high refractive index optical glasses, and durable multilayer deposition coatings, Explore Scientific 100° Series™ hyper-wide field eyepieces are optimized to produce high contrast, high resolution, and superior flat field characteristics, and yes they are indeed ruggedized and waterproof to withstand the outdoor environment.

See how easy it is to clean a waterproof eyepiece!

Most amateur astronomy is done outdoors, often with a group of people eager to get to look through the telescope. Eyepieces are often subjected to dew, humidity, pollens, dirt, dust, fingerprints, eye makeup, you name it...

Waterproof eyepieces are built for the outdoor environment and are worry-free as they keep the internal optics pristine. And cleaning them to the very edges of the glass is a breeze! Watch us at the Northeast Astronomy Forum as we demonstrate how to clean Explore Scientific Nitrogen Purged Waterproof Eyepieces

The visual effect of these eyepieces with their long eye-relief and their 100° apparent field is an extreme full-immersion experience. You have to try it understand the visual impact that these eyepieces produce.

Assembly of the first 14mm 100 degree eyepiece. The development of the Explore Scientific 14mm 100° Series Nitrogen-Purged Waterproof™ Eyepiece was a collaborative effort of astronomers and engineers who tested our prototypes again and again, in the field and in the factory to make refinements to produce the final production eyepiece.

Here we see the first prototype being assembled in the Kunming facility.

Inspiration for ultra-wide field eyepiece designs came from several designers. Wright H. Scidmore [1] patented important ultra-wide angle eyepiece designs (one with long eye-relief) in the ‘60s for the U.S. government. His influence can be seen in many eyepiece designs on the market today with eyepieces of 68 to 80 degrees apparent field and more. Carl Zeiss [2] made eyepieces of 110 and 120 degrees apparent field for use in U-boat periscopes before World War II. These are but two notable designers who developed ultra-wide field eyepieces over the decades.

Like all Explore Scientific eyepieces, the lens elements of the 100° 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.

Each optical surface is meticulously cleaned before and during assembly of each eyepiece.

These eyepieces with their huge apparent field of view not only gave the observer a panoramic visual experience, but they relax the eye so the observer could pay attention to subtle details for extended periods. These ultra-wide angle eyepieces played a critical role in the military for aiming at targets, and their long eye-relief counterparts helped reduce eye injury from recoil.

Testing for airtight seal. Each 100° Series Nitrogen-Purged Waterproof eyepiece is internally sealed and purged with inert, dry nitrogen gas to prevent internal fogging, to halt the intrusion of fine particulates and fungus, and to maximize the life of the internal coatings.

To make sure, every 100° eyepiece is tested by submerging them down to 1 meter of water for 30 minutes.

Years later such eyepiece designs transformed the visual experience for amateur astronomers, as they started using military surplus cannon sight eyepieces on their backyard telescopes. Al Nagler with his company Tele Vue introduced his Nagler 82 Degree eyepieces[3](and later introduced the 100 degree Ethos eyepieces), and then other commercial telescope companies such as Meade Instruments, Pentax, Celestron, and others made ultra-wide field eyepieces specifically for use in amateur telescopes. Since extreme performance eyepieces are expensive to make, they come with a relatively high price tag over standard eyepieces.

After announcing Explore Scientific’s line of telescopes at the Astronomical League Conference in the summer of 2008, we decided to focus on extreme performance, ultra-wide angle eyepiece designs as well. We 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 our facilities.

Here we are making final visual and cosmetic inspections where we check for assembly integrity, cleanliness, and optical performance (including a test for visual image edge consistancy) before shipping them to our customers.

Each Explore Scientific eyepiece is inspected at the factory where it is made and again at our facility for peak performance.

Developing our new eyepieces we wanted to take a fresh perspective and address several points. Our goal was to produce an ultra-wide angle design that provides pride of ownership at a great value:

Focus on Value - We invite direct comparison to any eyepieces on the market in their category.

Protection from the Outdoors - By making the eyepiece body nitrogen-purged and waterproof eyepiece internal elements will remain as pristine as the day they were assembled. The sealed, dry environment is impervious to internal fogging and contaminants such as fungus growing in between the lens elements. Our waterproof eyepiece is 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 insure a perfect seal we test every eyepiece in one meter of water for 30 minutes.

Creating an Identity - We look at purchasing fine optical equipment as an investment, and it should be treated as such. With a unique serial number on each eyepiece we can track when a product was made, and the owner can document their equipment for insurance and warranty purposes.

Providing Peace of Mind - Explore Scientific stands behind our products with a free 5 Year Transferrable Limited Warranty upon registration of the product. Want to trade or sell your eyepiece? You’ll get more value if its remaining warranty can be transferred to the new owner.

[1] Ref: W.H. Scidmore, Wide-angle eyepiece, USP 3390935 (1965), and USP 3384434 (1968)

[2] Ref: A New Telescope Eyepiece with Extremely Large Field of View by Horst Kohler, Oberkochen from Optik, Journal for Light and Electron Optics Special Reprint, Optik 17 (1960), pp500-509

[3] Ref: The eyepiece that changed observing, Astronomy Magazine (Dec, 2005)

Register Your Explore Scientific Eyepiece in the USA and Recieve a Free Five Year Extended Warranty Free Extended Warranty!

Buy an eyepiece for yourself or give it as a gift, then submit the registration form to receive a free extended five year warranty in the USA!

All Explore Scientific telescopes and telescope accessories are covered under our standard U.S.A. One Year Limited Warranty against defects with proof of purchase, but you can extend this limited warranty to five years by simply filling out the product registration and submitting it in within 60 days.

This program is also available to the person who receives your gift of an Explore Scientific eyepiece. You don't need to give them the purchase receipt, just remind them to fill out the registration, and we'll take care of the rest.

Additional Information

Name Explore Scientific - 9mm 100° Nitrogen-Purged Waterproof Fully Multi-Coated Eyepiece - 2"
Manufacturer Explore Scientific
Model EP1009-01
Discountinued Yes
Eyepiece Apparent FOV 100
Eyepiece Barrel Size 2"
Eyepiece Eye Relief 12.5
Eyepiece Focal Length 9
Warranty Explore STAR Transferrable Unlimited Lifetime Product Warranty