Explore Scientific 127mm f/7.5 Carbon Fiber FCD100 ED Triplet Refractor


Availability: In stock

This big 127mm (5") Explore Scientific Carbon Fiber air-spaced ED triplet apochromatic refractor is loaded with quality optical performance at a surprisingly reasonable price for a scope of its size and optical quality . . .
Our Product #: ES127CFFCD
Explore Scientific Product #: FCD100-127075-CF
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Product Description

This 5" Explore Scientific ES127 Carbon Fiber FCD100 apochromatic refractor has:
127mm f/7.5 fully multicoated triplet optics using a Hoya FPL53-equivalent FCD100 ED element
Dual-speed 2.5" Hexagonal focuser with 10:1 ratio fine focusing
Mounting rings with dovetail for use on a Vixen-style altazimuth or German equatorial mount
Finderscope base installed on OTA
Extended product lifetime warranty

With a 5" (127mm) aperture, this Explore Scientific Carbon Fiber ES127 FCD100 ED triplet refractor gathers 55% more light (with nearly 25% higher resolution) than the more common size 102mm (4") doublet and triplet refractors that often cost nearly as much as the ES127.

The Explore Scientific ES127 uses the premium Hoya FCD100 ED glass element and state-of-the-art optical multicoatings in its apochromatic air-spaced ED triplet optics. The result is images that are essentially free of the annoying halo of unfocused violet light (chromatic aberration) that mars the view of bright stars and solar system objects in lesser scopes, despite the scope's relatively large aperture, and even at very high magnifications.

The Explore Scientific ES127 is a natural on an equatorial mount as the heart of your primary observing system. In addition, it's an excellent astrograph for serious wide field imaging, as well as crisp solar system imaging. Considering its surprisingly reasonable price for a 5" apochromatic triplet and in view of the great optical performance that comes as standard equipment, the 5" Explore Scientific ES127 FCD100 is a terrific buy!

Features of this Telescope . . .

ED triplet refractor optics: 127mm (5") aperture, 952mm focal length, f/7.5 focal ratio three-lens air-spaced optical system. The optics use a center lens element of Hoya FCD100 (Dense Fluor Crown) glass, the Hoya equivalent of FPL-53 ED (Extra-low Dispersion) glass. This ED element produces superior sharpness and color correction by minimizing the chromatic aberration, the "false" color fringing seen around bright objects when light rays pass through standard crown-and-flint doublet objectives, particularly those with apertures in the ES127 class. Relying on technological innovation, Explore Scientific has successfully launched the mass production of high-performance optical glass at the apex of the FCD family. Combining it with optical glass of high refractive index allows them to achieve unprecedented advanced chromatic aberration correction. Hoya FCD100 is considered the best glass ever produced by Hoya.

Carbon fiber body: The body and dew shield of the 127mm Explore Scientific are made of woven carbon fiber fabric, encapsulated in epoxy. Carbon fiber, the same material used to fabricate much of the fuselage and wings of the new Boeing 787 Dreamliner passenger jet, has a high strength-to-weight ratio to keep the scope almost 20% lighter than comparable aperture aluminum-body scopes. In addition, it has low thermal expansion characteristics when subjected to temperature variations. This helps to keep the instrument sharply focused as the ambient temperature changes, which is particularly important during critical long-exposure CCD imaging.

Fully multicoated optics: The ES127 triplet objective lens has EMD™ (Enhanced Multilayer Deposition) antireflection multicoatings on all air-to-glass surfaces for high light transmission, minimal light scatter, and excellent contrast.

Internal light baffles: The aluminum tube body has contrast-enhancing internal light baffles and a specially darkened tube interior to provide dark sky backgrounds and high contrast.

Collimatable optics: One of the bonuses of owning a refractor is that, compared to standard reflector telescopes, they almost never require realigning of the optics (collimation). However, any air-spaced refractor telescope may require optical recentering if the lens elements are knocked out of alignment by a heavy blow during shipping or use. Removing the dew shield will give you access to the lens centering screws in the sides of the lens cell, which you can then adjust yourself by referring to the supplied instructions. You can also send your scope to Explore Scientific's Service Center for precision alignment. A standard service charge applies for factory realignment.

Dew shield: The supplied retractable dew shield slows the formation of dew on the lens in cold weather to extend your undisturbed observing time. It also improves the contrast, similar to the effect of the lens shade on a camera lens, when observing during the day or when there is excessive ambient light at night, such as a neighbor's backyard security light. A slip-on metal dust cap is standard.

Dual speed 2.5" Hexagonal focuser: The rotating precision-made no-backlash focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during high magnification visual observing and critical DSLR or CCD imaging. The large focus knobs have ribbed gripping surfaces so they are easy to operate, even while wearing gloves or mittens in cold weather.

The focuser drawtube has a scale marked in centimeters and 1mm increments. This lets you note individual focuser positions for easy return to the correct focus when switching between visual use and photography. Lock knobs let you adjust the tension on the drawtube to accommodate varying eyepiece/photo accessory loads, as well as firmly lock in a photographic focus. The focuser terminates in a non-marring 2" compression ring accessory holder. Two 2" draw tube extensions are included to let adjust the back focus when using a diagonal and eyepieces versus a camera.

Mounting rings and dovetail: The ES127 has dual split mounting rings with a dovetail plate that fits the Vixen-style dovetail slot on the head of many of the most popular medium capacity German equatorial mounts. Such mounts include Celestron and iOptron go-to mounts, among others. A spacer/stabilizing bar on the top of the rings provides a carrying handle that makes it easy to transport the optical tube and install it on your equatorial mount. There is a mounting shoe for an optional finderscope installed on the body of the scope.

Extended lifetime warranty: This individually serial numbered Explore Scientific telescope is backed by a limited one year warranty, which will be extended to an Explore Scientific transferable Life of The Product limited warranty when its warranty card is registered with Explore Scientific within 60 days of purchase. Full details on this unique transferable lifetime warranty.

Tech Details

Aperture 5"
Binary and Star Cluster Observation Very Good
Focal Length 952mm
Focal Ratio f/7.5
Galaxy and Nebula Observation Good
Highest Useful Magnification 271x
Lunar Observation Great
Weight 22 lbs.
Planetary Observation Very Good
Resolution 0.91 arc seconds
Telescope Type Refractor
Visual Limiting Magnitude 13
Warranty 1 year, extendable to lifetime


Review by:
I started doing astrophotography 1 year ago and went through 6 different types of scopes to finally settle on this APO. I purchased the carbon version and glad I did. Stars look awesome using the 3 inch .7 reducer. My prior scope was a big light bucket Newtonian that was a pain to setup each night of imaging. I miss it’s light gathering capabilities but hard to dial in consistently. No fussing with the APO and makes the hobby so much more enjoyable. Also tried the RASA at F/2 that had bad tilt issues and the secondary adapter would come loose on multiple occasions while at dark sites. If you want a scope with excellent glass then pull the trigger. I had to search all over the US to find this scope as it’s always out of stock for a reason. Quality
Also what helped me to up my game was combining the 127 with a ZWO2600 and 3nm Antlia filters for my bortle 6 backyard where I do most of my imaging. Here’s the latest image I have captured with this scope. Only a few hours of subs but the details are amazing. https://astrob.in/fmc9of/0/ (Posted on 8/14/2021)
Review by:
I have had this scope for 3 years now, time for me to step up with a review. In a nut shell this scope is worth twice as much as I spent for it. Explore Scientific put the best into this scope. For visual, one of the best scopes I have ever looked through. Excellent visual experiences easily translates into excellent imaging capabilities, which this scope excels at. I would get the CF version, for lighter weight and stability in changing weather situations. (Posted on 3/31/2020)
Review by:
I purchased one of these scopes a couple of years ago for the 2017 solar eclipse. The optics are excellent. The only complaint I would have is with the buckle clips that came with the mounting ring that seemed a bit weak. I noticed that the new version uses a much better mechanism for clamping the mounting ring. I currently use the scope on Losemandy G 11 mount that I have had for 25 + years that upgraded to use the newer DC servos and Gemini II control and have taken some great photos with this scope using a DSLR and also used it as a guide scope with a 500 canon lens. (Posted on 10/17/2019)
Review by:
Nice fit and finish - great views and lightweight. (Posted on 10/4/2019)
Review by:
The build of the scope body is excellent. The optics are excellent. As an added bonus, it does not break the bank for the quality received. (Posted on 7/24/2019)
Review by:
I've owned this scope for a couple of years now. This refractor is capable of turning out some great images when used with either the standard 1.0x flattener or the 0.7x reducer/corrector and an APS-C sized sensor or smaller. (Posted on 1/5/2019)
Review by:
This scope is top notch in fit and finish, however it really shines in optics especially for the money. If you're looking for excellent optics in the 5 inch category without breaking the bank this is it. (Posted on 10/6/2018)
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Supplied Accessories

  • Dual tube rings with Vixen-style dovetail
  • 2.5" dual speed Hexagonal focuser
  • Retractable dew shield
  • Dust covers
  • Finderscope base