Explore Scientific ED80-FCD100 Series Air-Spaced Triplet Refractor Telescope (Bundle)

An All-in-One f/6 Imaging System: The Explore Scientific ED80 Bundle

This package pairs the ED80-FCD100 optical tube with the iEXOS-100-02 PMC-Eight GoTo mount and the Explore Scientific field flattener for f/5 to f/7 refractors. It is set up for wide-field imaging of large nebulae, star clusters and galaxies.

The bundle is intended for observers who want to move beyond simple tripod photography and into the world of long-exposure, tracked imaging. Wireless GoTo control finds targets for you, and the 7.5 lb tube and portable mount travel easily to dark-sky sites.

HOYA FCD100 Triplet Optics

The heart of this telescope is its apochromatic air-spaced triplet objective lens. The design uses three lenses and HOYA FCD100 extra-low dispersion (ED) glass. The air-spaced triplet virtually eliminates chromatic aberration, the false color fringing seen around bright stars in simpler refractor designs.

Explore Scientific's proprietary EMD multi-layer coatings are applied to optimize light transmission. The theoretical resolving power of this optical system is 1.45 arc seconds, allowing for detailed views when seeing conditions permit.

The 80mm f/6 Optical Platform: A 480mm Wide-Field Window

The 80mm aperture and 480mm focal length give a wide field. On an APS-C sensor (about 23.5 by 15.6 mm) the field is about 2.8 by 1.9 degrees by plain arithmetic, which frames the bright body of the Andromeda Galaxy (M31) or the core of the North America Nebula (NGC 7000).

At f/6 the telescope needs less exposure for extended objects than slower f/8 or f/10 systems.

The Included f/5 to f/7 Field Flattener

The faster the focal ratio, the more field curvature becomes a problem: stars in the corners smear, and the larger the sensor, the worse it gets. The included field flattener goes between the telescope and the camera to correct this.

This specific flattener is designed for refractors with focal ratios between f/5 and f/7, which includes the f/6 ED80. It does not change the telescope's native 480mm focal length. Key features include:

• 2-inch Barrel: Attaches to a two-inch focuser or adapter.
• Fully Multi-Coated Optics.
• 38mm Clear Aperture: No sensor size or image circle is stated.
• Photographic Use Only: It is not intended for visual use.

Connecting Your Camera: Achieving 55mm Back Focus with M42 Threads

The flattener requires 55mm (+/-2mm) of spacing between the back of the device and the camera sensor. This distance is often called "back focus."

The flattener terminates in a male M42x0.75 thread, commonly known as a T-thread. To connect your camera you will use a T-ring (not included) for your camera's lens mount. A DSLR on a standard T-ring comes close to 55mm; mirrorless and dedicated astronomy cameras usually need M42 spacers to make up the distance.

The 2.5-inch Hex Focuser

The ED80-FCD100 is equipped with a 2.5-inch hexagonal rack-and-pinion focuser, rugged and providing precise control.

It supports imaging setups up to 10 lbs (4.5 kg). Weigh your camera, filters and any guider and stay within that figure.

iEXOS-100-02 Mount: 8-CPU PMC-Eight GoTo Control

The iEXOS-100 is a computerized German equatorial mount that serves as the foundation for this imaging system. It uses Explore Scientific's PMC-Eight Precision Motion Control system, with eight independent CPUs each dedicated to a specific task. This improves responsiveness, reliability, timing precision and tracking accuracy compared to traditional single-processor mounts.

The iEXOS-100-02 is rated at 19 lbs total for visual use and 15 lbs for photography, figures that include the counterweights; equipment weight alone is about 9 lbs. With the 7.5 lb ED80 tube that leaves room for a light camera. Key features of the mount include:

• Wireless Control: Built-in WiFi and Bluetooth allow you to control the mount from your tablet or computer without any dangling cables.
• ExploreStars App: The free app (available for Windows, Android, Amazon Fire, and Apple) handles mount alignment, object selection from a database of thousands of targets, and sky navigation.
• ASCOM Compatibility: Explore Scientific supports wired or wireless ASCOM connectivity through the PMC-Eight ASCOM driver and POTH Client, for most ASCOM-supported astronomy software. An ST4 auto-guider port is also provided.
• Portable Design: The mount and tripod are designed for portable astronomy. Glow-in-the-dark markings on the mount and tripod aid in setup in low-light conditions.

Beyond Imaging: Visual Use with the 80mm Triplet

While this bundle is optimized for astrophotography, the ED80-FCD100 optical tube also works visually, with sharp, high-contrast views of lunar details, planetary rings and deep-sky objects. The 80mm aperture provides bright images of objects like the Orion Nebula (M42) and the Hercules Cluster (M13), while the wide field of view is perfect for sweeping through the star fields of the Milky Way.

To use the telescope visually, you must remove the included field flattener, as it is designed for photographic use only. You will need a star diagonal and eyepieces, which are not in this bundle's box list. The GoTo functionality of the iEXOS-100 mount works just as well for visual observing, slewing to targets from the ExploreStars database and tracking them.

Field-Ready Build: A 7.5 lb OTA with Vixen-Style Dovetail

The optical tube assembly weighs 7.5 lbs (3.4 kg) and has a retracted length of 475 mm, making it easy to handle and transport. The tube's outer diameter is 100.7 mm. It has a dew shield (381mm tube length without it), which helps keep dew off the objective and blocks stray light.

The telescope attaches to the iEXOS-100 mount via a Vixen-style dovetail, which also fits other Vixen-style saddles. Explore Scientific's catalog lists the Hybrid Finder Scope Base for the FCD100 series, designed to accept legacy Explore Scientific finder brackets and mini dovetail-type finder brackets.

What Is in the Box

The bundle has six items in its box list.

The package includes the main ED80-FCD100 optical tube, the iEXOS-100 GoTo equatorial mount head, the matching field flattener, a sturdy field tripod with an accessory tray, two 2.2 lb counterweights for balancing, and a battery pack to power the mount. The only additional items you need to provide are a camera, any necessary adapters to achieve 55mm back focus, a power source for extended use, a star diagonal and eyepieces for visual use, and your control device (tablet or computer). For a detailed list of every component, please see the "In the Box" tab.

Your First Night Out: A 4-Step Quick Start Guide

The iEXOS-100 manual covers setup in full; in short:

Following this process will prepare your system for either visual observation or astrophotography. For imaging, you would proceed to connect your camera and control software after these steps are complete.

1. Assemble and Level: Set up the tripod, attach the iEXOS-100 mount head, and level the entire assembly using the integrated bubble level. Attach the counterweight bar and the two 2.2 lb counterweights, but leave them loose for now.
2. Mount and Balance the Telescope: Attach the 7.5 lb ED80 optical tube to the mount's Vixen-style saddle. With the clutches loose, carefully balance the telescope in both the Right Ascension axis (by sliding the counterweights) and the Declination axis (by sliding the telescope forward or backward in the saddle). A good balance is crucial for accurate tracking.
3. Polar Align: Point the mount roughly towards north (or south in the Southern Hemisphere). Use the integrated polar alignment sight hole to center Polaris (or the appropriate southern stars) in the view by adjusting the mount's altitude and azimuth controls.
4. Power On and Connect: Connect the battery pack or a 12V DC supply to the mount's 12V DC in port. On your tablet or computer, connect to the mount's WiFi network (SSID: PMC-Eight-xxxx, password "PMC-Eight" per the manual). Launch the ExploreStars app or your ASCOM software, connect to the mount, and perform a 2-star or 3-star alignment to sync the mount with the sky. You are now ready to GoTo your first target.