Explore Scientific 18mm 82° field argon-purged waterproof 2" eyepiece


Availability: In stock

This 82° field Explore Scientific 18mm 2" argon-purged waterproof eyepiece makes observing with many telescopes feel like you're taking a stroll through the cosmos rather than looking through an eyepiece.
Our Product #: ES8218A
Explore Scientific Product #: ESWP8218-01

Product Description

This 2" 18mm Explore Scientific is an exceptional medium focal length eyepiece with a wide, wide 82° field. It makes observing feel like you're floating above the Earth, taking a space walk, rather than looking through a telescope eyepiece, particularly with short focal length scopes such as fast focal ratio apo refractors or Dobsonian reflectors.

In addition to its wide field, the 18mm Explore Scientific has an extra benefit for you. It is O-ring sealed and nitrogen-purged to be 100% waterproof. This prevents internal fogging in the eyepiece; keeps the interior dust-and fungus-free; and makes it easier to clean, as there is no risk of excess cleaning solution getting trapped between the lenses.

The latest computer design programs have been used to optimize its performance. Its six element/four group design uses low dispersion and high refractive index lenses and full multicoatings for high contrast, high resolution, and flat field images across its very wide 82° field of view. The lens edges have been blackened to improve contrast.

A 10" f/4.5 Dobsonian reflector will have a full 1.29° field at 63.5x with this eyepiece, able to encompass all of the Pleiades in one field. Even an 8" f/10 catadioptric will have a field almost one and a half lunar diameters across, able to encompass the full Moon with room to spare, the Orion Nebula, and many globular clusters, as well. You can use the calculator in the "formula" tab above to see just how wide the field will be with your particular telescope.

At 13mm, the eye relief will somewhat vignette the field of view for eyeglass wearers. This isn't as much a problem as you might think, as the 82° field of view is so wide that even non-eyeglass wearers have trouble seeing the whole field at once. All observers have to move their eye from side to side to take in the immense view, so vignetting in the conventional sense is not a problem. This is one of those eyepieces that can truly be described as showing you a "picture window view" of space. The visual effect of its long eye-relief and 82° apparent field is truly a full-immersion experience. Your eye is relaxed, allowing you to easily use the "averted vision" technique to study faint details across its huge field of view.

The eyepiece has a soft fold-down rubber eyecup and comes with dust covers for both ends of the eyepiece.

This individually serial numbered Explore Scientific eyepiece is backed by a limited one year warranty, which will be extended to an Explore Scientific transferable product lifetime limited warranty when its warranty card is registered with Explore Scientific within 60 days of purchase. Here's a link to the full details on this unique transferable lifetime warranty.

Tech Details

Barrel Size 2"
Eye Relief 13mm
Field of view 82
Focal Length 18mm
Number of optical elements 6
Weight 14 oz.
Warranty 1 year, extendable to lifetime


Review by:
I purchased this eyepiece to go with my 16" Sky Watcher and it is my "go to" eye piece! Spectacular views of nebulae and M13 is awesome...spent several hours just being amazed at the clarity and resolution. Of course it helps to have a great telescope as well! As noted in other reviews, eye relief is comfortable, and that is a good feature when assisting others observing through your scope at a star party. Overall a great value! (Posted on 10/31/2019)
Review by:
One of several ES ep's I own, these 82 degree eyepieces really bring out the best in my 10" and especially my 15" dob. There's nothing better than feeling adrift in a field of stars or taking in multiple targets in a single fov. No, they're not Televue's, but they are the next best thing, and are unmatched at this price range. (Posted on 9/20/2019)
Review by:
I use this as my low power EP in my 10" F/5 dobsonian, and I love it. Provides great wide views, with not too much magnification for the scope. When it is on sale, that makes it an even better deal than it currently is! (Posted on 8/14/2019)
Review by:
A great mid range eyepiece with nice eye relief. The field of view is just right for the magnification. Great views of nebula and galaxies. The water proof and air fog is very helpful given the humid temperatures. (Posted on 8/2/2019)
Review by:
I use this with a 12.5" f4/8 dob for a 1.0 deg FOV. Great for finding objects.

The original ep I received was defective: there was a piece of the o-ring seal dangling from the top of the barrel. I notified Astronomics and they sent out a new eyepiece even before receiving the old one back - excellent customer service! (Posted on 1/4/2019)
Review by:
This is the ocular I use the most. It has a great magnification while giving you the "Lost in Space" feeling. Light enough I can use it in my 6 SE SCT. Optics are phenomenal, no apparent aberrations, or fringes. (Posted on 12/4/2018)
Review by:
Excellent value!!! Deep sky or planetary viewing is (if I may borrow a phrase) tack sharp. Eye relief is very comfortable for my 70yo eyes. (Posted on 11/20/2018)
Review by:
ES82 18mm is one of the great bargains in the hobby for its high performance in a critical mid-power spot in most eyepiece kits at a reasonable cost. Some nights it has been the only eyepiece in the focuser for open clusters marathons, for instance. And with most scopes it runs at exit pupils friendly to narrowband filters for those big Summer emission nebulae. I have long thought it may be the very best of the ES82 series. (Posted on 10/30/2018)
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