Explore Scientific 100° 5.5mm Waterproof Eyepiece - 2"

The 5.5mm View: A 100° High-Magnification Spacewalk

With a 5.5mm focal length, this eyepiece provides significant power for splitting tight double stars, resolving planetary details like Jupiter's cloud belts, and examining the cores of globular clusters. The expansive 100° apparent field transforms this high-power view into a panoramic experience, framing the object in a wide expanse of black sky that makes you feel as if you're looking through a porthole in space.

To ensure maximum contrast, all optical elements are fully multi-coated and edge-blackened. This suppresses internal reflections and scattered light, allowing the faintest details to stand out against a dark background, which is critical when pushing magnification to its limits.

Built for the Field: Waterproof to 1 Meter and Argon-Purged

This eyepiece is engineered to withstand the harshest observing environments. The optical housing is sealed and purged with dry argon gas, an inert element that prevents internal fogging during rapid temperature drops and stops mold or fungus from forming on the internal lens surfaces. This process maximizes the lifespan of the delicate optical coatings.

Every eyepiece in the 100° series is rigorously tested by submerging it in 1 meter of water for 30 minutes. Whether you observe in a dew-soaked field or a humid climate, you can be confident that your eyepiece is protected from the elements, night after night.

Observing with 100°: Extended Tracking and Averted Vision

The hyper-wide 100° field offers practical advantages beyond aesthetics. For observers using non-driven telescopes like Dobsonians, an object will drift across the field of view for a very long time before the telescope needs to be nudged. This allows for more relaxed, extended study of your target at high power.

This wide expanse also enhances the use of averted vision, a critical technique for observing faint objects. The generous field gives your eye ample room to look slightly to the side of a target like the Veil Nebula (NGC 6960), placing its faint light on the more sensitive part of your retina and making subtle details pop into view.

100° vs. 82° Fields: What You Gain with a Hyper-Wide Eyepiece

While 82° eyepieces are a significant step up from standard designs, the jump to a 100° field provides a distinctly more immersive view. An 82° eyepiece can feel like looking at a large screen, whereas a 100° eyepiece fills your peripheral vision, largely removing the boundary of the field stop from your consciousness.

• Situational Awareness: The wider field of the 100° design makes it easier to star-hop and locate challenging targets at high magnification, as you can see more of the surrounding star patterns for context.
• Framing Large Objects: Even at the high power of 5.5mm, the 100° field allows you to better frame larger targets, such as the full disc of the moon or the Orion Nebula (M42), without feeling constrained by the edges of the view.