Explore Scientific 100° 14mm Waterproof Eyepiece - 2"

The 100° Series Experience

You may be startled at the wide expanse of inky black sky the first time you look through a 100° Series eyepiece, and may even forget there is an eyepiece between you and the universe. In a non-driven telescope, an object stays in the field a very long time before any adjustment is needed.

It says the huge field relaxes the eye so you can pay attention to subtle details for extended periods, and makes averted vision easy: looking slightly to the side of a faint object puts the image on a part of your eye that is more sensitive to light, allowing you to see fainter images.

The Visual Impact of a 100° Apparent Field

The 100° field is close to the maximum for hyper-wide eyepiece design, giving a panoramic visual experience.

It says objects are easier to locate with such a field.

14.5mm Eye Relief and Observing Comfort

Eye relief is the fixed distance from the eyepiece's top lens to the point where your eye must be positioned to see the full field of view. The Explore Scientific 100° 14mm has an eye relief of 14.5mm.

Explore Scientific does not say how much of the field eyeglass wearers see.

9-Element Construction

The 14mm uses 9 lens elements. It has an optimized optical design, exotic glass combinations for optimum results and durable coatings.

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

Argon-Purged and Waterproof to 1 Meter

Each 100° Series eyepiece is internally sealed and purged with inert, dry argon gas, with a waterproof, fog-proof housing.

It says the purge also maximizes the life of the internal coatings, and every 100° eyepiece is tested by submerging it to 1 meter of water for 30 minutes.

The 2-Inch, 836 g Tapered Barrel

The 100° 14mm uses a 2-inch barrel. Measuring 157mm in length and 70mm in diameter, this is a substantial ocular with a weight of 836 grams (29.4 oz).

Observers should be mindful of this weight, as it may require rebalancing the telescope when switching from a much lighter 1.25-inch eyepiece. The barrel is tapered for extra security.

Calculating True Field with a 24.4mm Field Stop

The eyepiece's field stop is the physical metal ring inside the barrel that creates the sharp, black edge of the field of view. Its diameter is the ultimate limit on how much sky you can see. For the 14mm 100° eyepiece, this diameter is 24.4mm.

You can calculate the true field of view (TFoV) this eyepiece will deliver in your specific telescope using the field stop diameter. The approximate formula is: TFoV ≈ (Field Stop Diameter / Telescope Focal Length) x 57.3. For example, in a telescope with a 2000mm focal length, the 14mm eyepiece would yield a true field of approximately (24.4mm / 2000mm) x 57.3 ≈ 0.7 degrees. At 1200mm it is about 1.17 degrees.

Power Calculations for the 14mm Focal Length

The magnification is determined by your telescope's focal length, calculated with the simple formula: Magnification = Telescope Focal Length / 14mm.

Here are a few examples to illustrate its range:

• 600mm focal length: 600 / 14 = 43x.
• 1200mm focal length: 1200 / 14 = 86x.
• 2000mm focal length: 2000 / 14 = 143x.

Using Explore Scientific 2-Inch Focal Extenders

Optional focal extenders are available for the 100° Series, and a focal extender increases the magnification of any eyepiece with the same barrel size.

With the 2-inch barrel, you can use the following models:

• Explore Scientific FE02-020 (2x): This doubles the magnification, effectively turning your 14mm eyepiece into a high-power 7mm eyepiece.
• Explore Scientific FE03-020 (3x): This triples the magnification, yielding an effective focal length of approximately 4.7mm.

Care, Storage, and What's Included

Because the housing is sealed, only the outer lenses ever need cleaning, and only when needed.

When not in use, the eyepiece should be stored with both dust caps in place to protect the optical surfaces. The eyepiece ships with the following components:

• 14mm 100° Waterproof Eyepiece: The main eyepiece body.
• Dust Cap (Top): Protects the large eye lens.
• Dust Cap (Bottom): Protects the 2-inch barrel and field lens.