Explore Scientific · Apochromat Refractor
Explore Scientific ED102 FCD100
Premium apochromatic refractor with genuine FCD100 glass for sharp, color-accurate views at a serious price point
Price updated Mar 22, 2026
Performance Scores
Overview
The Explore Scientific ED102 FCD100 is a 102mm apochromatic refractor built around genuine HOYA FCD100 extra-low dispersion glass, one of the most capable ED glass types available in this aperture class. At f/7, the 714mm focal length strikes a reasonable balance between portability and versatility, handling both wide-field deep-sky viewing and planetary work with equal competence. The proprietary EMD multi-layer coatings on all optical surfaces maximize light transmission and contrast, which translates to noticeably crisper stars and better separation of fine detail compared to standard achromatic refractors at similar apertures.
Chromatic aberration, the purple or green fringing that plagues cheaper refractors, is effectively controlled here. You can push magnification on the Moon, planets, and double stars without the color fringing that would otherwise limit your views. The included alt-az mount keeps the package manageable for transport, though serious astrophotographers will likely want to pair this optical tube with a dedicated equatorial platform.
At just under 11 pounds, portability is reasonable for a 4-inch instrument of this optical quality. The single Amazon review, while perfect, should not carry much weight in your decision; this scope deserves evaluation on its optics and reputation rather than limited user feedback.
At a Glance
102mm
Aperture
f/7
Focal Ratio
4.94kg
Weight
Specifications
Key Features
- Uses genuine HOYA FCD100 glass, a premium ED material that delivers true apochromatic correction with minimal residual color fringing
- EMD enhanced multi-layer coatings on all optical surfaces improve contrast and light transmission compared to standard multi-coatings
- 102mm aperture at f/7 resolves fine planetary detail and tight double stars while still performing well on brighter deep-sky objects
- Weighs 4.94kg, making it portable enough for travel without sacrificing optical quality
- Included finder scope allows quick target acquisition in the field
- Alt-az mount provides a straightforward setup, though upgrading to an equatorial mount is advisable for astrophotography
- Chromatic aberration is controlled well enough to support high magnification without the color fringing common in achromatic designs at this price range
Customer Reviews
1 reviews