Eyepiece Celestron Omni 4 mm 1.25" fully coated optics, MPN 93316

The Celestron Omni 4 mm 1.25" eyepiece is a compact, high-power ocular designed for visual lunar and planetary observation with telescopes that accept 1.25" eyepieces. Its fully coated optical elements reduce reflections and increase contrast, delivering detailed views at high magnification when paired with a suitable telescope and star diagonal. The metal barrel fits standard 1.25" focusers and diagonals, making this eyepiece compatible with a broad range of amateur instruments.

Advantages

This 4 mm eyepiece offers strong magnification for close-up views of the Moon and planets while maintaining a compact form factor that is easy to handle and store. Fully coated optics improve light transmission and reduce ghosting, resulting in sharper edges and better contrast on fine surface details. The industry-standard 1.25" barrel ensures wide compatibility with common telescopes and diagonals, and the durable construction supports frequent use in field conditions.

Suitable for

• Lunar surface observation and crater detail studies
• Planetary observation including Jupiter, Saturn and Mars
• High-magnification views of double stars and small bright deep-sky objects
• Use as a high-power option in an eyepiece set for amateur astronomers

Key specifications

• Focal length: 4 mm
• Barrel diameter: 1.25 inches
• Optical treatment: fully coated lenses for improved transmission
• Form factor: compact, metal barrel construction
• Intended use: visual observation at high magnification

How to use

Insert the eyepiece into a 1.25" focuser or star diagonal and secure it with the focuser’s thumbscrew or clamp. Use the eyepiece with a telescope of appropriate focal length to achieve the desired magnification; this eyepiece provides very high magnification and is best used with steady atmospheric conditions. When changing eyepieces, handle the metal barrel by its outer surface and avoid touching the lens elements. Clean the external lenses only with appropriate optical cleaning tools and a gentle technique to prevent coating damage.

Usage recommendations

For optimal results, use the eyepiece on nights of good seeing with a stable mount and tracking. Combine with a quality star diagonal and low-dispersion optics where available. Avoid using this high-power eyepiece on telescopes with very short focal lengths that produce uncomfortable eye relief or excessively narrow fields of view.