Explore Scientific 127mm FCD100 Carbon Fiber ED Triplet Apochromatic Refractor (ES127CF-FCD100)
A 5" apochromatic refractor has long been considered a sweet spot in amateur astronomy—a serious instrument for those who want visual and photographic performance without sacrificing portability. The Explore Scientific 127mm FCD100 Carbon Fiber Triplet hits that mark with authority. Whether you’re scanning lunar rilles at high magnification, splitting tight double stars, or imaging deep-sky objects with pinpoint stars across the frame, this scope delivers the kind of performance you can count on night after night.
What makes this telescope stand out is how much you’re getting: premium ED optics, carbon fiber construction, and a precision 2.5" dual-speed focuser, all in a package that’s surprisingly light for its size. Add in a lifetime transferable warranty, and it becomes one of the most compelling mid-aperture refractors on the market—especially when compared to many competing scopes that cost more but deliver less.
Serious Glass for Serious Observers
At the heart of the ES127 is its triplet objective lens, built around a center element of Hoya FCD100 ED glass, the optical equivalent of Ohara’s legendary FPL-53. This ultra-low dispersion glass is engineered to focus red, green, and blue wavelengths at the same point, dramatically reducing chromatic aberration—the faint purple fringing you see in lower-end refractors when looking at bright stars or the lunar limb. In the ES127, that color error is essentially gone.
The result? Clean, high-contrast views of Saturn’s rings, detailed images of the Moon’s terminator, and color-true stars that sparkle without halos. For astrophotographers, the benefits are even more obvious: tight star images across the field, with no bloated blue stars or chromatic smearing during long exposures.
A Lightweight Workhorse with Heavyweight Performance
Despite its 5" aperture, the carbon fiber tube and dew shield keep this scope lighter than you might expect—roughly 20% lighter than comparable aluminum-tube models. That means less strain on your mount, faster cooldowns at night, and less flexure or sag during imaging sessions.
But the real benefit of carbon fiber goes beyond the weight. Unlike metal, which expands or contracts significantly as the temperature changes, carbon fiber is dimensionally stable. That means the focus you dial in at the start of the night stays put, even as the ambient temperature drops. If you’re imaging across multiple hours—or doing fine visual work with tight focus tolerance—this can make a real difference.
Focusing Made for Astronomers, Not Just Telescopes
The included 2.5" dual-speed hexagonal focuser is a pleasure to use. It rotates for optimal camera framing, locks securely, and features coarse and 10:1 microfine focusing for precise control. Large ribbed knobs are easy to grip, even with gloves on, and the graduated drawtube markings let you record focus positions when switching between visual and imaging sessions.
Two included 2" extension tubes make it easy to accommodate various setups, from a star diagonal and eyepiece to a field flattener and DSLR. The compression ring holder grips accessories firmly without marring barrels—a welcome touch for anyone who’s ever cringed at a thumbscrew scar on a favorite eyepiece.
Whether you’re trying to hit perfect focus for a CCD camera or dial in sharp detail on Jupiter at 250x, this focuser gives you the confidence and control to get it right.
Designed for the Real World
Explore Scientific designed this scope not just to look good in a spec sheet, but to perform reliably in the field. Every detail reflects real observing experience:
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A retractable dew shield slows dew formation and reduces stray light—helping you stay focused on the object, not fighting glare.
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Internal knife-edge baffles and a matte-black interior preserve contrast and eliminate reflections from bright off-axis light sources.
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The lens cell is collimatable, though most users will never need to touch it unless the scope suffers a hard impact.
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A metal slip-on dust cap protects the optics during storage or transport.
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A pre-installed finderscope base lets you easily add the aiming device of your choice.
Ready for Your Mount—and Your Next Adventure
The scope includes dual split mounting rings and a Vixen-style dovetail plate, compatible with many medium-duty mounts from Celestron, iOptron, Sky-Watcher, and others. The rings are connected at the top by a stabilizer bar that doubles as a convenient carry handle—a small but welcome detail that makes setup and teardown easier, especially in the dark.
At 127mm aperture and 952mm focal length, this refractor hits the perfect balance between resolution, field of view, and portability. It’s just as at home doing high-power lunar work as it is wide-field imaging of the Veil Nebula. Pair it with a field flattener or 0.7x reducer and you’ll have an imaging platform that performs like a scope twice its cost.
A Lifetime Investment in Astronomy
Every ES127 FCD100 is individually serial numbered and covered by Explore Scientific’s limited one-year warranty, which extends to a Lifetime Transferable Product Warranty when registered within 60 days of purchase. That means the scope retains full warranty coverage even if you sell it, giving it added long-term value few manufacturers offer.
Specifications
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Optical design: Apochromatic air-spaced triplet refractor
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Aperture: 127mm (5")
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Focal length: 952mm
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Focal ratio: f/7.5
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Glass type: Hoya FCD100 ED element (FPL-53 equivalent)
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Dew shield: Retractable carbon fiber
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Tube material: Carbon fiber
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Focuser: 2.5" dual-speed rotating hex focuser with 10:1 fine focus
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Back focus accessories: Two 2" extension tubes included
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Accessory holder: 2" compression ring
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Mounting: Dual rings with Vixen-style dovetail and top carry handle
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Finderscope base: Installed
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Dust cap: Slip-on metal
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Weight (approx.): 18 lbs (OTA only)
