Eyepiece Explore Scientific 100° 5.5 mm 2-inch for telescopes

Explore Scientific 100° 5.5 mm 2-inch eyepiece is a wide-angle telescope eyepiece designed for visual astronomy. With a 5.5 mm focal length and a 100° apparent field of view in a 2" barrel, it delivers high magnification suitable for detailed observation of the Moon, planets and close double stars when used with telescopes that accept 2" eyepieces. The eyepiece is intended to provide an expanded field of view and comfortable eye relief for observers who require a combination of high power and wider apparent sky coverage.

Advantages

The 100° apparent field of view increases immersive visual coverage compared with narrower eyepieces, making star fields and extended lunar scenery easier to inspect. The 5.5 mm focal length produces high magnification for resolving fine planetary detail and separating close stellar pairs. The 2" barrel form factor ensures compatibility with standard 2" focusers and allows the eyepiece to be used in a variety of medium- to large-aperture telescopes. Optical design and eye relief are optimised for comfortable viewing sessions without excessive eye strain.

Suitable for

• High-magnification planetary observation
• Lunar detail and crater studies
• Double-star resolution and splitting
• Narrow-field deep-sky inspection of compact nebulae and star clusters
• Observers using telescopes with 2" focusers seeking a wide apparent field at high power

Key specifications

• Focal length: 5.5 mm
• Apparent field of view: 100°
• Barrel diameter: 2 inches
• Intended application: visual astronomy (planetary, lunar, double stars)
• Compatibility: telescopes with 2" focusers

How to use

Insert the 2" barrel fully into the focuser or diagonal of a compatible telescope and secure it with the focuser’s thumbscrews. Start with a lower magnification eyepiece to find and centre the target, then switch to the 5.5 mm eyepiece for high-magnification views. Adjust the telescope focus slowly until the image is sharp. Use the eyepiece’s eye relief position to achieve a full field of view; minor adjustments in eye position may be required to see the entire 100° apparent field. When observing bright targets such as the Moon or planets, reduce exposure to glare by using appropriate filters or slightly stopping down the aperture if necessary.

Recommendations

For best results, use the eyepiece on telescopes with sufficient aperture and stable mounting to support high magnifications. High magnification increases sensitivity to atmospheric seeing; choose nights with steady seeing for planetary and double-star work. Consider using a Barlow lens only if compatible with the desired magnification and eye relief, and employ planetary filters to improve contrast on bright targets.