Explore Scientific 9mm 100º Eyepiece - 2"

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Explore Scientific 9mm 100º Eyepiece - 2"
Item # ES-EPWP1009-01
  • The Explore Scientific 9mm 100 Eyepiece has been getting lots of thumbs up from seasoned amateur astronomers and now you can have one of your very own for a great price!
  • The eyepiece is waterproof and nitrogen-purged, and it comes with a replaceable soft, folding eyecup.
  • Eye relief on the Explore Scientific 9mm 100 Eyepiece is 9mm, the barrel is 2" and accepts 2" filters.


Explore Scientific 9mm 100º Eyepiece

The development of the Explore Scientific 9mm 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.

Inspiration for ultra-wide field eyepiece designs came from several designers. Wright H. Scidmore 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 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.

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.

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 (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 USA facility in California.

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 consistency) before shipping them to our customers.

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.

Explore Scientific 9mm 100º Eyepiece Specifications

  • Focal Length: 9mm - FOV: 100 degrees

  • Waterproof: Submersible to 1 meter for 30 minutes; Nitrogen-purged to prevent internal fogging

  • Coatings: All lens-to-air surfaces are full multi-coated

  • Barrel: 2.0" diameter, tapered barrel-style, accepts 2.0" diameter standard filters

  • Eyecup: Soft rubber folding style; Replaceable

Manufacturer Product Number: EPWP1009-01

Additional Information

Additional Information

SKU ES-EPWP1009-01
UPC Code 812257014651
Manufacturer Explore Scientific
Optical Design Wide Angle
Barrel Size 2"
Warranty Lifetime Warranty
Eyepiece Field of View - Apparent 100º
Eyepiece Focal Length 9mm
Eyepiece Eye Relief 12.5mm
Eyepiece Manufacturer Series Explore Scientific 100º Waterproof
Eyepiece Weight 1 lb. 8 oz.
Field Stop Not supplied by manufacturer
Number of Lens Elements & Groups Not supplied by manufacturer
Special Feature Waterproof
Comes with Dust Caps? Yes
Comes with Eye Guard? Yes

Customer Reviews 5 item(s)

Awesome eyepiece
I love this eyepiece. The wide field of view is great for finding nearby objects. I use manual setting circles on my 12" f/5 dobsonian and I can usually get an object within the field of view of this eyepiece. It even works great in my Celestron 130SLT, though it's not as necessary with a goto scope.

I love the clarity of the eyepiece and brightness the eyepiece gives. I can often see objects better than or equal to my other lower magnification eyepieces (Baader Hyperions).
1= Houston, We Have a Problem & 5= It's Out of This World
Review by Robert / (Posted on 8/3/2015)
Very Nice Eyepice
I bought both ES100 9mm and ES82 11 mm to compare one to another. Contrast and sharpness was similar. At last, I've chosen ES100 though it's two times heavier.
100 degree view is awesome! I believe, this bomb-eyepiece become my favorite with Dob 10 f1/5. A bit of coma right at the edge of the view but it doesn't matter for me.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by AstroN / (Posted on 11/1/2011)
Excellent & versatile eyepiece
I bought this eyepiece during the ES winter sale here at OPT at the beginning of the year. It was a little out of my budget (I also bought the 82 degree 11mm and 14mm eyepieces while on sale but OPT's return policy convinced me to take a chance, so I ordered it about 1/2 hour before their free shipping promo expired.

The 9mm worked very well in my 12 f/5 LightBridge and a fellow astro club member's 12 Sky-Watcher dob. He owned a 13mm Ethos so we were able to test against one another. It provided a FOV similar to the 14mm 82 degree ES eyepiece that I had also bought, though with more magnification. It was sharp across the field with a little softness creeping in right at the edge. Contrast and sharpness was on-par with the Ethos with a similar softness at the edge, though not as pronounced.

Thinking that I might go ahead and return it due to the FOV being similar to the 82 degree 14mm (and being out of my budget, I had one last thing I wanted to try, and decided that if it worked out that I would keep the 9mm and figure out how to balance my budget to afford it.

I also do a little astrophotography and had earlier purchased an Antares 2 x0.7 focal reducer for use with a Starshoot CCD camera I have. If screwed on to the end of the ES 9mm it would turn it into a 12.9mm eyepiece (or 14.2mm if I used the ring I had bought for the 17mm Hyperion I also own, but would it work OK or not?

The next evening I was able to go out I took the focal reducer with me and was again able to test it against the 13mm Ethos. It worked wonderfully well. The softness at the edge creeped in a tiny bit more, but the contrast and sharpness remained on par with the Ethos.

And I definitely enjoyed the larger true FOV at both 12.9mm and 14.2mm than I did at 9mm on many objects! And it makes it a most versatile eyepiece when used with the focal reducer, as some targets are better at 9mm than at the lower magnification with the reducer.

I ended up selling my Baader Clickstop Hyperion Zoom eyepiece to balance my budget so I could keep this eyepiece (the purchase of these ES eyepieces made the Clickstop less necessary.

I've been very happy with the Explore Scientific eyepieces I have purchased and feel they are an incredible value compared with the their completion. If I had returned the 9mm 100 degree eyepiece I would have at some point in the future purchased the 14mm version from Explore Scientific (another astro club member has one of these and I love it.

But I'm real glad things worked at as they have and am happy to be able to use this as a 9mm, as well as a 12.9mm and a 14.2mm.

1= Houston, We Have a Problem & 5= It's Out of This World
Review by James Lummel / (Posted on 5/18/2011)
Excellent Eyepice
Wonderful viewing thrue my 10 ince newtonion reflector, very sharp images all the way to the edge of the f.o.v and no coma.
A little bit big and heavy.
I will recomend it to a friend.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by chayp / (Posted on 3/16/2011)
Great Eyepiece
I started with the 14mm eyepiece, and love the 9mm too. With my next pay check I will complete the set (20mm. Observing is great when three eyepieces cover 90% of your needs. The view through my 16 Dob is awesome.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by Grant / (Posted on 9/1/2010)
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Included Items

  • Explore Scientific 9mm 100º Eyepiece
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