Explore Scientific ED80-FCD100 Air-Spaced Triplet Refractor Telescope with 0.8x Focal Reducer (Bundle)

The ED80-FCD100 & iEXOS-100 Bundle: A Complete Imaging Platform

This package puts the ED80-FCD100 optical tube together with the 0.8x Focal Reducer, made for the FCD100-0806-02, and the iEXOS-100-02 GoTo mount.

It suits the imager who wants a wide field of view and computerized GoTo tracking in a package light enough to carry to a dark site.

Apochromatic Optics: 80mm Air-Spaced Triplet with HOYA FCD100 Glass

The optical heart of this telescope is its 80mm air-spaced apochromatic triplet objective. The design uses three lenses to bring the colors of the visible spectrum to a common focus and virtually eliminates chromatic aberration, the false color fringing (typically purple or blue halos) seen around bright stars and planetary limbs in simpler refractor designs.

The triplet uses HOYA FCD100 extra-low dispersion (ED) glass. Explore Scientific's proprietary EMD enhanced multi-layer deposition coatings are applied to all optical surfaces.

0.8x Focal Reducer: A Faster f/4.8 System for Wide-Field Astrophotography

The included 0.8x Focal Reducer has two elements. It shortens the focal length, which gives two advantages for astrophotography.

• Faster Focal Ratio: The reducer converts the telescope's native f/6 into f/4.8. On extended objects that needs about 36% less exposure time for the same signal ((4.8/6) squared is 0.64).
• Wider Field of View: By reducing the effective focal length from 480mm to 384mm, this accessory widens the telescope's field of view. On an APS-C sensor (about 23.5 by 15.6 mm) the field grows from about 2.8 by 1.9 degrees to about 3.5 by 2.3 degrees, enough for the Andromeda Galaxy (M31) by plain arithmetic.

Camera Connection: 55mm Back Focus and M42 T-Threads

The 0.8x reducer ends in a male M42x0.75 thread, commonly known as a T2 thread, and takes a 42 mm T-ring. To attach your camera you need the T-ring for your camera's lens mount.

Allow 55mm (+/- 2mm) between the device and the camera sensor. A DSLR on a standard T-ring comes close to this; mirrorless and dedicated astronomy cameras usually need spacers, so check your camera maker's figures.

Precision Focusing: 2.5-inch Hexagonal Focuser with 10 lb Capacity

The ED80-FCD100 is equipped with a 2.5" hexagonal focuser.

It has a load capacity of 10 lbs (4.5 kg). Weigh your camera train, filters and any guider and keep the total within that figure.

iEXOS-100 Mount: Wireless PMC-Eight GoTo Control

The bundle includes the Explore Scientific iEXOS-100-02, a computerized German equatorial GOTO tracking system designed for portable astronomy and astrophotography. Once polar aligned, an equatorial mount follows the sky's rotation on one axis, so long exposures do not show field rotation.

At the core of the mount is the PMC-Eight controller, which uses eight independent CPUs dedicated to specific tasks. This improves responsiveness, reliability, timing precision and tracking accuracy compared to traditional single-processor mounts. Key features of the system include:

• Wireless GoTo Control: Built-in WiFi and Bluetooth allow you to control the mount wirelessly with the free ExploreStars app for Windows, Android, Amazon Fire and Apple tablets.
• ExploreStars App: The app handles alignment, slewing and browsing information on thousands of astronomical targets. It features 2-star and 3-star alignment routines to synchronize the mount with the sky.
• 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.
• Power & Balancing: The included battery pack takes 8 C-cell batteries (not included); alkaline batteries typically last less than two hours, so use a lithium-ion power bank or AC power adapter for extended use. The bundle includes four counterweights: two 1 kg weights and two supplemental 2.2 lb (ES-CW22-00) weights.

Visual Observing: A Portable Scope for Rich-Field Views

While optimized for imaging, the ED80-FCD100 also works for wide-field observing. With a 2-inch diagonal and a low-power 2-inch eyepiece (neither is in this bundle's box list), the 80mm aperture and 480mm focal length show wide views of open star clusters, large nebulae and Milky Way star fields.

An 80mm aperture limits high-magnification planetary detail, though Jupiter's cloud bands and Saturn's rings are within reach. Its strength lies in providing a rich, wide-angle window onto the deep sky.

Mechanical Design: A 3.4 kg Tube with Vixen Dovetail

The optical tube weighs 3.4 kg and is 475mm long retracted. It has a dew shield, which helps keep dew off the objective and blocks stray light.

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

Your First Night: From Assembly to GoTo Alignment

Follow the iEXOS-100 manual for the full procedure; in short:

1. Assembly: Set up the tripod and attach the iEXOS-100 mount head. Install the counterweight shaft and as many counterweights as balance requires. Mount the 80mm telescope tube to the Vixen saddle.
2. Balancing: With all your gear attached (camera, etc.), balance the telescope in both the Right Ascension and Declination axes. Proper balance is crucial for GoTo accuracy and tracking.
3. Power and Connection: Install batteries in the battery pack or connect a 12V DC supply to the 12V DC in port. On your tablet or PC, connect to the mount's "PMC-Eight-xxxx" WiFi network (password "PMC-Eight" per the manual).
4. Polar Alignment: Perform a rough polar alignment by aiming the mount north and setting the latitude scale. For better accuracy, look through the integrated polar alignment sight hole to center Polaris (in the Northern Hemisphere).
5. GoTo Alignment: Launch the ExploreStars app. Follow the on-screen instructions to perform a 2-star or 3-star alignment. This tells the PMC-Eight system where it is pointing. You are now ready to select a target and begin exploring.