30mm 82° field argon-purged waterproof 2" eyepiece

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This 2” 30mm Explore Scientific is an excellent low power eyepiece with an ultra-wide 82° field of view, one so wide you have to move your head from side to side to see it all. It is particularly suited to get the maximum image brightness and field of view out of big Dobsonian scopes, but will work well with any scope that can use 2" eyepieces, even an f/15 Maksutov. Viewing through this 30mm Explore Scientific makes you feel like you’re floating above the Earth, taking a space walk, rather than looking through a telescope eyepiece. If you want a truly relaxed and unconfined “picture window” view of the Universe, this is the eyepiece for you.

With an f/4.5 Dobsonian reflector, this 30mm eyepiece has a very large 6.7mm exit pupil larger than some observers’ eyes can dilate. That can effectively waste some of the Dob’s light gathering capacity for those observers, as some of the full light cone will fall on their iris, rather than entering his or her eye. Even so, many observers are willing to trade a little light gathering for the jaw-dropping fully-immersive view through this 82° apparent field eyepiece. If you want to see the big picture, this is an eyepiece you will treasure for years to come.

In addition to its wide field, the 30mm Explore Scientific has an extra benefit for you. It is O-ring sealed and argon-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 12" f/4.5 Dobsonian reflector gives you a full 1.79° field at 45.7x with this eyepiece, well over three lunar diameters, and easily able to encompass all of the Pleiades or Orion in one field. You get over seven minutes of uninterrupted observing with such a scope while an object drifts from one side of the sharp and flat eyepiece field to the other. That’s plenty of time for multiple observers to look at the same object, or for you to absorb as much detail as possible, before having to reposition the scope. Even an 8” f/10 catadioptric has a 1.23° field that’s almost two and a half lunar diameters across, for thrilling views of the larger nebulas, like the Omega and Orion. Use the calculator in the "formula" tab above to see just how wide a field you’ll get with your particular telescope.

With 21mm of eye relief, this 30mm Explore Scientific eyepiece provides unvignetted views for eyeglass wearers, although the 82° field of view is so wide that even non-eyeglass wearers can’t see the whole field at once. All observers have to move their eye from side to side to see out to the field stop.

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 lifetime limited warranty when its warranty card is registered with Explore Scientific within 60 days of purchase. This link will give you full details on this unique transferable lifetime warranty.

Field of view:
The field of view (FOV) is the amount of observable world one can see at any given moment.
82°
Eye Relief:
Eye relief is the distance from the last surface of the eye lens of an eyepiece to the plane behind the eyepiece where all the light rays of the exit pupil come to a focus and the circular image is formed, sometimes called the “Ramsden Disk.” This is where your eye should be positioned to see the full field of view of the eyepiece. If you must wear glasses because of astigmatism, you’ll usually need at least 15mm of eye relief or longer if you want to see the full field of view with your glasses on.

A note on our eye relief figures: Quite often, our eye relief figures will differ from those of the manufacturer. This is because we measure the “usable” eye relief, while the manufacturers specify their usually-longer (but technically correct) “designed” eye relief.

The eye lens of the eyepiece is normally recessed below the rubber eyeguard or rubber rim of the eyepiece to keep the lens from being scratched during use. An eyepiece might have a “designed” eye relief of 15mm (and the eye relief will truly measure 15mm from the eye lens to where the image forms). However, if the eye lens is recessed 3mm below the eye guard, the Ramsden Disk forms only 12mm above the eyepiece body (the 15mm “designed” eye relief, less the 3mm of eye relief made unusable by having the eye lens recessed into the body of the eyepiece). This “usable” eye relief of 12mm (measured from the rolled-down eyeguard – the closest point you can get your eye to the eye lens – to where the image forms) is the eye relief figure we would measure and list in this website.

Why is it important to list the “usable” eye relief? For those people who don’t wear eyeglasses while observing, a few mm difference between the eye relief they expect from the manufacturer’s literature and the shorter eye relief they actually get in real life doesn’t mean a lot. They can simply move a little closer to the eyepiece to see the full field, and never realize that the eye relief is a little shorter than they expected. However, some people must wear eyeglasses while observing, because of severe astigmatism. These observers can’t move closer to the eyepiece if the eye relief is shorter than expected because their glasses get in the way. For these people, the real life “usable” eye relief is more important than the technically correct but sometimes not fully usable “designed” eye relief. We measure and list the actual usable eye relief so that people in the real world can pick the eyepieces that will work best for them.

21mm
Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

30mm
Number of optical elements:
6
Barrel Size:
The industry standard diameter, as of 2011, is 1.25" and is the most common.  Other sizes available are .965" and 2".
2"
Weight:
The weight of this product.
2.2 lbs.
Warranty:
1 year, extendable to lifetime
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Helpful Formulas
Telescope Eyepiece Formula
To calculate the magnification and approximate actual field of view of this eyepiece on your telescope, enter the focal length of your telescope below and press the "Calculate" button.

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30mm 82° field argon-purged waterproof 2" eyepiece

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30mm 82° field argon-purged waterproof 2" eyepiece
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Our Product #: ES8230A
Manufacturer Product #: EPWP8230-01
Price: $299.99  FREE ground shipping - Click for more info
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MSRP: $667.99
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This 82° field Explore Scientific 30mm 2” argon-purged waterproof eyepiece gives you the big picture, making you feel like you’re relaxing in front of an expansive picture window on the Universe, rather than squinting through an eyepiece.





. . . our 34th year