A 5-inch triplet APO refractor has traditionally been a $3,000+ investment — putting premium refractor performance out of reach for observers who want serious aperture without serious chromatic aberration. The Explore Scientific ED127 Essential Series delivers 127mm of true apochromatic optics at a price point that makes triplet refractor performance accessible to serious observers and astrophotographers who would otherwise need to compromise on aperture or glass quality.

Key Features

• 127mm HOYA FCD1 ED glass triplet — air-spaced apochromatic design with EMD enhanced multi-layer coatings virtually eliminates chromatic aberration for true-color views of planets, double stars, and deep-sky objects
• Dual-speed 2" rack-and-pinion focuser — 10:1 fine-focus ratio with heavy-duty locks prevents drift under heavy imaging payloads; drawtube marked in cm and 1mm increments for repeatable focus positions
• Adjustable front lens cell — push-pull collimation screws allow precise optical alignment for pinpoint stars, a feature rarely found at this price point
• 0.91 arcsecond resolution — resolves tight double stars, Jupiter's cloud belt detail, and Saturn's Cassini Division at the theoretical limit for 127mm
• Retractable dew shield — shortens tube from 41.75" to 33.25" for compact transport without removing any components
• Vixen-style dovetail and cradle rings — universally compatible with most equatorial mounts; integrated handle doubles as a 1/4"-20 DSLR piggyback mount for wide-field imaging alongside your main camera
• Two 2" drawtube extensions included — adjust backfocus distance for compatibility with a wide range of eyepieces and camera setups

Ideal For

• Intermediate astrophotographers upgrading from an achromat or reflector — the ED127 eliminates the false color and diffraction spikes that compromise long-exposure images, and the locked dual-speed focuser holds critical focus through multi-hour sessions
• Visual observers who want a refractor that shows planets and double stars with textbook-sharp Airy discs and clean color — the adjustable collimation lets you dial in perfect star shapes
• Portable setups — at 18 lbs the OTA pairs well with mid-range mounts like the Explore Scientific EXOS2-GT PMC-Eight and the retractable dew shield makes it easy to fit in the Explore Scientific Soft-Sided Case

Accessories & Compatibility

The ED127 ships with a 99% reflective 2" dielectric star diagonal, a hybrid 2N1 finder scope base (finder sold separately), dual split cradle rings with Vixen-style dovetail, retractable dew shield with dust covers, and two 2" drawtube extensions for backfocus adjustment.

For astrophotography, pair with the Explore Scientific 3" Field Flattener / 0.7x Focal Reducer to flatten the field across your sensor and reduce the effective focal ratio to f/5.25 for faster imaging. Add an 8x50 Illuminated Right Angle Finder for comfortable target acquisition without straining your neck.