Explore Scientific 82° 4.5mm LER Waterproof Eyepiece - 1.25"

An Immersive 82° Field at a High-Power 4.5mm Focal Length

The 82° field naturally promotes relaxation at the eyepiece, makes it easier to observe for longer, and promotes the use of averted vision, looking slightly to the side of a faint object so its light falls on a more sensitive part of your eye. The 4.5mm is perfect for objects that benefit from high magnification, such as the Moon, the planets and binary stars, and for detailed examination of structure within nebulae, when the air is steady.

15.9mm of Long Eye Relief for Viewing Comfort

High-magnification observing requires steady, comfortable eye placement. This eyepiece is designed with 15.9mm of eye relief, a feature that defines it as a Long Eye Relief (LER) model. Long eye relief is especially important for eyeglass wearers because it allows them to enjoy the full field of view.

7-Element/5-Group Optics with EMD Coatings

The 4.5mm LER uses 7 elements in 5 groups. The edge-blackened optics are made of low-dispersion glass with a high refractive index, and each lens is fully multi-coated with durable EMD coatings, for sharp contrast, high resolution and crisp definition.

Argon-Purged Waterproofing in a 275g Body

Explore Scientific's waterproof eyepieces are gas-purged and O-ring sealed to create a waterproof environment that is impervious to internal fogging and keeps contaminants out of the housing, which makes cleaning easy. The 1.25" barrel fits standard focusers and diagonals, and the eyepiece weighs 275 g.

The 4.5mm LER vs. Longer Focal Lengths: High-Power Applications

The 4.5mm focal length places this eyepiece firmly in the high-magnification category. It suits close double stars such as the Double-Double (Epsilon Lyrae) and planetary detail. The trade-off for this power is a smaller true field of view compared to a longer focal length eyepiece from the same 82° series. Longer focal lengths in the series suit large objects; the 4.5mm is for small targets. It is also more sensitive to atmospheric turbulence and demands steady skies to deliver its best performance.

• Focal Extender Compatibility: You can increase the magnification further by pairing this eyepiece with an optional 1.25" focal extender. A 2x extender would make it act like a 2.25mm eyepiece, which is beyond the useful magnification of most telescopes, so a 2x extender suits longer focal lengths better.
• High-Power Targets: Lunar craters and rilles, Jupiter's belts, Saturn's rings and small planetary nebulae such as the Ring Nebula (M57), in steady air.