Explore FirstLight 102mm f/9.8 Doublet Refractor Telescope (OTA only)

A 102mm f/9.8 achromatic doublet refractor that delivers sharp, high-contrast views of the Moon and planets — sold as an optical tube assembly for observers who already own a mount or want to choose their own.

The long f/9.8 focal ratio is naturally forgiving of eyepiece quality and produces tight, well-corrected star images without the coma or field curvature that faster telescopes struggle with. The 1000mm focal length reaches useful planetary magnifications with common eyepieces — a 10mm eyepiece delivers 100x, enough to split Saturn's rings and resolve Jupiter's cloud belts. Fully multi-coated optics maximize light transmission through the doublet objective.

Ships with everything you need except a mount: a 90° star diagonal for comfortable viewing angles, a 25mm Plossl eyepiece (40x) for finding and framing targets, a red-dot finderscope for alignment, and a smartphone camera adapter for quick lunar snapshots.

Key Features

• 102mm (4") achromatic doublet objective, fully multi-coated
• 1000mm focal length, f/9.8 — optimized for high-contrast planetary views
• Includes 90° diagonal, 25mm Plossl eyepiece, red-dot finder, smartphone adapter
• Vixen-style dovetail for universal mount compatibility

Ideal For

• Mount owners adding a refractor — the Vixen dovetail drops onto any compatible equatorial or alt-az mount
• Planetary and lunar observers — f/9.8 delivers the high contrast that planets demand
• Budget-conscious beginners — the most affordable FirstLight refractor OTA, ready to pair with any mount