Explore Scientific ED102 102mm f/7 Triplet APO Refractor Telescope

Explore Scientific ED102 102mm f/7 Triplet APO Refractor TelescopeFinding a 4 inch triplet APO refractor under $1,000 used to be impossible the optics alone typically cost more than that. The Explore Scientific ED102 Essential Series is the only 102mm air spaced triplet APO refractor available under $1,000, delivering diffraction limited optics with HOYA FCD1 extra low dispersion glass that produces the color free, high contrast views visual observers and astrophotographers demand at this aperture. Key Features HOYA

Finding a 4-inch triplet APO refractor under $1,000 used to be impossible — the optics alone typically cost more than that. The Explore Scientific ED102 Essential Series is the only 102mm air-spaced triplet APO refractor available under $1,000, delivering diffraction-limited optics with HOYA FCD1 extra-low dispersion glass that produces the color-free, high-contrast views visual observers and astrophotographers demand at this aperture.

Key Features

• HOYA FCD1 Extra-Low Dispersion Glass – S-FPL51 equivalent ED glass in a three-element design minimizes chromatic aberration, delivering clean, true-color views with excellent contrast across the field
• Air-Spaced Triplet Optical Design – Three-element apochromatic configuration achieves 1.14 arcsecond resolution and diffraction-limited performance guaranteed at 0.25 PV or better
• Aluminum Optical Tube – Rigid construction with flat-black interior coatings and internal baffles for maximum contrast and stray-light suppression
• 2" Dual-Speed Rack-and-Pinion Focuser – Smooth, rotatable focuser with 10:1 fine focus ratio for precise adjustments during both visual and imaging sessions
• EMD Enhanced Multi-Layer Coatings – Proprietary broadband coatings on all air-to-glass surfaces maximize light transmission and contrast
• Versatile f/7 Focal Ratio – Long enough for high-magnification lunar and planetary detail, yet pairs well with a field flattener for deep-sky imaging
• Retractable Dew Shield – Blocks stray light and slows dew formation during extended sessions
• 99% Reflective 2" Diagonal Included – Premium dielectric diagonal maximizes light throughput right out of the box

Ideal For

• Visual observers who want true apochromatic performance — sharp, color-free views of Jupiter's cloud bands, Saturn's rings, and tight double stars — without the $1,200+ price tag of FCD100/FPL-53 triplets
• Beginning astrophotographers stepping into refractor imaging with a DSLR or dedicated camera — the triplet design produces cleaner star profiles than any doublet at this price, and the f/7 ratio is forgiving to work with
• Budget-conscious astronomers who want the sharpest possible 4-inch optics for under $700 — competing triplet APOs start at $1,200 and up
• Upgraders from achromats or doublet EDs ready for the next level of color correction and contrast without jumping to the $1,200–$3,000 premium triplet tier

Accessories & Compatibility

• Explore Scientific Field Flattener (f/5–f/7) – Eliminates field curvature for sharp, flat stars edge-to-edge in deep-sky imaging — recommended for astrophotography with this scope
• Explore Scientific 8x50 Illuminated Right Angle Polar Finder – Accurate polar alignment with an illuminated reticle for precise tracking during long exposures
• Explore Scientific Twilight I Alt-Azimuth Mount – Smooth manual tracking for visual observing sessions — a natural pairing for grab-and-go use
• Explore Scientific EXOS2-GT Equatorial Mount – GoTo motorized mount with PMC-Eight system for automated object tracking and long-exposure astrophotography
• Explore Scientific Soft-Sided Telescope Case – Padded protection for safe transport to dark-sky locations

Ready for the imaging upgrade? The ED102 FCD100 steps up to HOYA FCD100 glass (Abbe 95.10 vs 81.61) and a heavier-duty 2.5" hexagonal focuser rated for 10 lbs of imaging gear — the choice for serious astrophotographers who need near-zero chromatic aberration.

Note: A finder scope and carrying case are not included. The pre-installed 2N1 finder scope base accepts most standard finder scopes and guiding systems.