EXPLORE SCIENTIFIC FCD100 127MM — AIR-SPACED TRIPLET ED APO REFRACTOR
The Explore Scientific FCD100 Series 127mm f/7.5 is a premium apochromatic refractor built for serious visual observers and astrophotographers who will not accept color fringing, soft stars, or compromised contrast. It occupies a specific and well-regarded position in the refractor market — large enough at 5 inches of aperture to reveal meaningful detail on planets, deep-sky objects, and lunar terrain, while precise enough in its optical design to satisfy observers who have outgrown entry-level and mid-range instruments.
This is the aluminum tube version in classic white — the same optical specification as the carbon fiber variant but housed in an aluminum optical tube assembly that prioritizes durability and value over minimum weight.
THE OPTICS — HOYA FCD100 ED GLASS AND EMD COATINGS
The FCD100 designation refers to HOYA's premium extra-low dispersion glass — one of the highest-performing ED glass types available in commercial telescope production. In optical performance characteristics, HOYA FCD100 is comparable to Ohara FPL-53, the glass standard used by many competing premium refractors. The air-spaced triplet design spaces three lens elements with air gaps between them rather than cementing them together, which allows each element to be individually optimized for aberration control and produces superior chromatic correction across the full visual spectrum.
Explore Scientific's proprietary EMD enhanced multi-layer coatings are applied to every optical surface in the system — not just the front element. This reduces internal reflections, maximizes light transmission, and delivers the high-contrast, high-color-fidelity images the FCD100 series is known for. The result is diffraction-limited optical performance, meaning the telescope performs at the theoretical maximum resolution limit imposed by its aperture rather than being constrained by optical aberrations.
At 127mm aperture with a 952mm focal length, the FCD100 resolves to 0.9 arcseconds and reaches a limiting magnitude of 13 — performance that translates to clearly separated double stars at tight separations, cloud banding and the Great Red Spot on Jupiter, Cassini's Division in Saturn's rings, and meaningful structural detail in bright nebulae and galaxies.
THE FOCUSER — 2.5-INCH HEX CRAYFORD
The 2.5-inch HEX focuser is one of the more practical differentiators of this telescope compared to refractors in a similar aperture range. The hexagonal drawtube design provides exceptional rigidity that standard round Crayford focusers cannot match at equivalent drawtube diameters, eliminating the rotational flex and slippage that becomes problematic under the weight of a heavy camera and accessories. The focuser is rated to support up to 10 pounds of imaging equipment without slipping or introducing field tilt — a meaningful specification for astrophotographers planning to use a DSLR, mirrorless camera, or dedicated astronomy camera with filter wheels or other accessories.
Two extension tubes are included for additional back-focus distance flexibility when adapting various cameras and diagonals.
PHYSICAL DESIGN AND PORTABILITY
The FCD100 aluminum tube weighs 18 pounds — significant but manageable on any mount rated for its capacity, and meaningfully portable compared to Newtonians and Schmidt-Cassegrains of equivalent aperture. The integrated dew shield extends tube length to 41.75 inches in use and retracts to 33.25 inches for storage and transport, reducing the overall packaged footprint without requiring a separate dew shield accessory.
The cradle ring with integrated carry handle makes balancing on an equatorial or alt-az mount straightforward, and the included Vixen-style dovetail plate is compatible with the vast majority of modern telescope mounts. The hybrid 2N1 finder scope base is pre-installed on the tube and accepts both legacy Explore Scientific finder scope brackets and mini dovetail type finder scopes from Vixen, Synta, and Celestron.
Explore Scientific backs the FCD100 Series with a lifetime warranty — a statement of confidence in the build quality that distinguishes it from competing instruments with standard limited warranties.
WHY BUY FROM THE PRIME PINNACLE
The Prime Pinnacle is an authorized Explore Scientific dealer shipping to the continental United States with free shipping and no sales tax outside Florida. Our FL-based, first responder-owned support team is available before and after purchase at +1 (877) 477-2853 or support@theprimepinnacle.com.
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SKU: FCD100-127075-02
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Optical Design: Air-spaced triplet apochromatic refractor
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Glass Type: HOYA FCD100 extra-low dispersion (ED)
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Coatings: EMD enhanced multi-layer on all optical surfaces
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Aperture: 127mm (5 inches)
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Focal Length: 952mm
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Focal Ratio: f/7.5
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Limiting Magnitude: 13
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Resolution: 0.9 arcseconds
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Tube Length with Dew Shield Extended: 41.75 in (1,060mm)
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Tube Length without Dew Shield: 33.25 in (849mm)
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Tube Diameter: 130mm
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Tube Material: Aluminum — classic white finish
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Weight: 18 lbs (8.2 kg)
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Focuser: 2.5-inch HEX Crayford-style
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Focuser Payload Capacity: Up to 10 lbs
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Dovetail: Vixen-style plate included
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Finder Scope Base: 2N1 hybrid base pre-installed
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Diagonal: 99% reflective 2-inch diagonal included
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Warranty: Lifetime warranty from Explore Scientific
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FCD100 127mm f/7.5 aluminum optical tube assembly with integrated dew shield
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2.5-inch HEX focuser with 2 extension tubes
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Cradle ring with carry handle
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Vixen-style dovetail plate
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2N1 hybrid finder scope base pre-installed
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99% reflective 2-inch diagonal
Not included:
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Mount and tripod (sold separately)
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Eyepieces (sold separately)
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Finder scope (base is pre-installed, finder sold separately)
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Soft case (available as an accessory)
Warranty: Explore Scientific provides a lifetime warranty on the FCD100 Series. Contact The Prime Pinnacle at support@theprimepinnacle.com or +1 (877) 477-2853 for warranty support.
