Explore Scientific 127mm FCD100 f/7.5 ED APO Triplet Refractor

  • Aperture: 127mm (5")
  • Focal Ratio: f/7.5
  • Focal Length: 952mm
  • Top notch refractor that is totally free of chromatic abberation
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  • Regular price $2,399.99

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Explore Scientific 127mm FCD100 f/7.5 ED APO Triplet Refractor

Expose the wonder of Earth's celestial neighborhood with the Explore Scientific 127mm FCD100 Refractor. You'll experience the beauty of the barren lunar landscape, the smooth elegance of Saturn's ring structure, the most luminous deep sky objects in the Messier catalog, and more!

For all intents and purposes, the 127mm FCD100 is the same instrument as the Explore Scientific 127mm Essential Series Refractor, but with higher quality optics. Explore Scientific uses Hoya FCD100 extra-low dispersion (ED) glass which has characteristics analogous with Ohara FPL-53 glass. With a true diffraction-limited optical design and compact size, the 127mm FCD100 is a premium quality refractor that has been made to inspire impromptu stargazing adventures.

By combining Hoya FCD100 optics with Explore Scientific's proprietary EMD enhanced multi-layer coatings on all optical surfaces, the 127mm FCD100 air-spaced triplet refractor produces radiant images with high contrast while avoiding chromatic aberrations almost entirely.

This incredible little scope also comes with a 2.5" Hexagonal focuser that features an extremely rigorous design and support for up to 10 lbs. of accessories.

Even though the 127mm FCD100 is an outstanding telescope by itself, it is also small enough to mount on a larger instrument. This gives you flexibility when astro-imaging by splitting guiding and imaging responsibilities between the two scopes.

OPT Product Number: ES-FCD100-12775


Aperture127 mm (5")
Free ShippingYes
ManufacturerExplore Scientific


  • Explore Scientific 127mm FCD100 f/7.5 ED APO Triplet Refractor
  • 2" Star Diagonal
  • 2.5" Hexagonal Focuser
  • Cradle Ring with Handle
  • Vixen-style Dovetail
Customer Reviews
4.2 Based on 5 Reviews
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Jeffrey S.
United States United States
Good scope, poor shipping and loctite on focus ******

I bought this scope for serious astrophotography. Scope is amazing (optics wise) I assume but I can't use it. First of all shipping box from OPT had 1 piece of tape on top and bottom so scope parts were hanging out the bottom of box when it was delivered. Box was fine...tape was falling off (obviously). Black dove tail on scope rings rings had HUGE scratch on it almost like they sent me a used scope. Scope itself looked fine. However, the focus ****** which you need to remove if you want to install an autofocuser like the moonlite, has loctite on the threads. No way to get it off. Reading forums some had to use heat gun and strap wrench to remove. However, I had to send scope to Explore Scientific for them to remove. Took 4 of their people and they couldn't remove and they broke a strap wrench in the process so they are moving my optics to another scope with ****** loosened. Still haven't received back but Explore Scientific has EXCELLENT support and for that reason I will not avoid them in the future. I let OPT sales person know of my shipping issue and scratch on dovetail when they asked what I think of scope but no one contacted me after I reported the issues. Complete silence. Guess they only respond when there's good news....makes me want to order from other vendor next time.

Caleb S.
Solid Refractor

I recently purchased this scope along with some massive upgrades to my gear back in August and have been taking it for a spin almost every clear night we have here. For visual observation it has been really great, especially for planetary and lunar observation. I've been steadily working my way into DSLR AP and I've only hit one real issue with it and that is that I get these weird spikes when imaging stars that are in focus. The support team from ES has been very responsive in trouble shooting what might be the cause (probably the travel screws that come with it to help keep the optics in place), but I'll have to wait a week to do another test run. Overall, very, very pleased with this scope and the quality of my purchase. Thanks for all the help OPT for sorting through gear questions and helping with the purchase.

Mike M.
Focuser needs work

Good glass. I stepped up from a 72mm doublet, and I use a 294 osc. My only complaint is the focuser. It's quite notchy. It will focus, but it's very rough. I made a few adjustments but it's not better. I may upgrade to a moonlite in the very near future. Great scope

Stephen M.
United States
Great refractor

I upgraded to the Explore Scientific127mm f/7.5 FCD100 ED APO Refractor from the Explore Scientific 102mm f/7 APO Refractor that I have had for almost a year. The 127mm is a significant improvement over the 102mm. The images achieved are much sharper and larger due to the increase in diameter and FOV area. I am extremely pleased with both of the extremely fine Explore Scientific Refractors and would recommend them to anyone.

Roger S.
United States
5 inch APO Explore Scientific Refractor

I have never owned a refractor before. My only experience with telescopes has been with 8 inch and 10 inch SCT's which are awkard to setup. The 5" refractor is dong a fine job. It is much easier to setup and the view is more or less "the same" as larger scopes using mirrors. I am using a Celestron AVX mount which is what I had been using with the 8 inch Meade SCT OTA..