Explore Scientific 82° 30mm Waterproof Eyepiece - 2"

The Explore Scientific 82° 30mm: An Immersive 2" Low-Power Eyepiece

At 30mm it is the longest focal length in the 82° Series, so it gives the lowest magnification and the widest true field of the series in a given telescope, which suits finding objects and sweeping the Milky Way.

An 82° Apparent Field at 30mm

The effect of the 82° field and long eye relief is a full-immersion experience. The comfortable ultra-wide field promotes relaxation at the eyepiece, so it is easier to observe for longer and details begin to materialize that were not apparent at first glance.

The wide field also makes averted vision easy: looking slightly to the side of a faint object puts its light on a part of your eye that is more sensitive to light, allowing you to see fainter images.

21.6mm of Eye Relief for Uncompromised Viewing Comfort

The eyepiece features a generous 21.6mm of eye relief, which is the distance your eye must be from the top lens to see the entire field of view. You do not need to press your eye against the lens.

Long relief is a must for eyeglass wearers because it allows them to enjoy the full field of view.

A 7-Element/4-Group Design with EMD Coatings

The 30mm has 7 lens elements in 4 groups. The computer design, combining low dispersion and high refractive index glasses with durable EMD coatings, is optimized for high contrast, high resolution and flat field characteristics.

• Enhanced Multilayer Deposition (EMD) Coatings: Durable EMD coatings on the lenses.
• Edge-Blackened Lenses: Lens edges are blackened to minimize scattering of light within the lenses.
• Internal Baffling: All internal surfaces of the barrel are flat black to keep internal reflections to a minimum.

Argon-Purged Waterproofing for All-Weather Reliability

Each 82° Series eyepiece is O-ring sealed and purged with an inert gas to create a waterproof environment and a fog-proof housing.

The lenses sit in precision machined metal barrels that keep the optical train aligned for years of rugged use in the field.

The Tapered 2" Barrel

The 43mm field stop needs a 2" barrel. The eyepiece measures 131mm long and 82mm wide and weighs 1007 g, so use a focuser that holds it firmly.

A tapered 2" barrel adds extra security.

Calculating True Field of View from the 43mm Field Stop

The true field of view (TFOV), how much actual sky the eyepiece shows, is determined by its 43mm field stop diameter and your telescope's focal length. You can estimate the TFOV in degrees using the formula: TFOV ≈ (Field Stop / Telescope Focal Length) * 57.3.

For example:

• 2000mm focal length: about 1.23°.
• 1200mm focal length: about 2.05°.
• 800mm focal length: about 3.08°.

30mm Focal Length: Calculating Magnification for Your Telescope

To calculate the magnification this eyepiece will provide with your telescope, use the formula: Magnification = Telescope Focal Length / 30mm.

The resulting power will vary depending on your instrument:

• 2800mm focal length: Magnification is 93x.
• 2000mm focal length: Magnification is 67x.
• 1200mm focal length: Magnification is 40x.
• 700mm focal length: Magnification is 23x.

Expanding Magnification with Explore Scientific Focal Extenders

Explore Scientific Focal Extenders raise magnification while keeping the eyepiece's native apparent field and eye relief.

The 2" models give:

• With a 2x Focal Extender (FE02-020): The eyepiece performs like a 15mm, 82° eyepiece.
• With a 3x Focal Extender (FE03-020): It performs like a 10mm, 82° eyepiece.

Built for the Field: Durability and Handling a 1007g Eyepiece

The Explore Scientific 82° 30mm is constructed from a precision-machined metal barrel and optical housing, built for years of rugged use. At 1007 g (35.5 oz), expect to rebalance the telescope when switching to or from small 1.25" eyepieces.

The sealed design keeps contaminants out and makes cleaning easy.