Explore Scientific ED80-FCD100 Series Air-Spaced Triplet Refractor Telescope + Field Flattener f/5 to f/7 (Bundle)

An Imaging-Ready f/6 Bundle for Wide-Field Astrophotography

This package is designed for astrophotographers seeking a portable, high-contrast instrument for capturing expansive deep-sky objects. By bundling the ED80-FCD100 optical tube with the ES-FF2F5/F7 Field Flattener, this package addresses two challenges of wide-field imaging: chromatic aberration and field curvature. It suits imagers using DSLR, mirrorless or dedicated astronomy cameras; no sensor size is stated for the flattener, which has a 38mm clear aperture.

The tube weighs 3.4 kg. The ED80 also makes a versatile guiding scope when paired with larger telescopes.

The 80mm Air-Spaced Triplet with HOYA FCD100 Glass

At the core of this telescope is an 80mm air-spaced triplet objective lens using HOYA FCD100 extra-low dispersion (ED) glass. The air-spaced triplet virtually eliminates chromatic aberrations, the false color and purple fringing often seen around bright stars in less-corrected designs. The triplet configuration allows for a higher degree of color correction than a standard two-lens doublet, with true-to-life color fidelity.

Good color correction matters for one-shot-color cameras, which record red, green and blue at the same focus position, so low false color keeps bright stars from showing colored halos.

A 480mm Focal Length for Expansive Deep-Sky Fields

The telescope's 480mm focal length and 80mm aperture combine to produce a fast f/6 focal ratio. 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), the core of the North America Nebula (NGC 7000) or one side of the Veil Nebula.

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

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. This bundle includes the Explore Scientific ES-FF2F5/F7 Field Flattener, designed for refractors with focal ratios between f/5 and f/7, which includes the f/6 ED80.

The flattener has a 2-inch barrel, fully multi-coated optics and a 38mm clear aperture, and it is for photographic use only. It does not change the telescope's 480mm focal length.

Achieving 55mm Back Focus with the M42x0.75 T-Thread

The flattener requires 55 mm (+/- 2 mm) of spacing between the back of the device and the camera sensor. A DSLR on a standard T-ring comes close to this; mirrorless cameras have a shorter flange distance and need extra spacers.

The rear of the flattener features a male M42x0.75 T-thread, for your camera's T-ring (not included). Dedicated astronomy cameras usually need M42 spacers to make up the 55mm distance.

The 2.5-inch Hexagonal Focuser with a 10 lb Load Capacity

The ED80-FCD100 is equipped with a 2.5-inch hexagonal focuser capable of supporting heavy imaging accessories, with a load capacity of 10 lbs (4.5 kg). Weigh your camera, filters and any guider and stay within that figure.

Explore Scientific includes two extension tubes for flexible spacing.

Attaching the 3.4 kg OTA with the Included Vixen Dovetail

The optical tube assembly weighs 3.4 kg (7.5 lbs) and comes with a Vixen-style dovetail for mounts with a Vixen-style saddle.

For astrophotography, use a tracking equatorial mount. Add your camera and accessories to the 3.4 kg tube and choose a mount whose imaging capacity comfortably exceeds the total. Explore Scientific also sells this tube and flattener as a package with its iEXOS-100-02 mount.

High-Contrast Views with an 80mm Apochromatic Objective

While this bundle is optimized for astrophotography, the ED80-FCD100 also works visually: remove the field flattener and insert a 2-inch star diagonal (a 99% reflective 2-inch diagonal with a 1.25-inch adapter is available for the FCD100 80mm) and an eyepiece. Expect clear, high-contrast views of deep-sky objects and planetary detail.

Jupiter's main cloud belts and four Galilean moons and the rings of Saturn are within reach of 80mm. The ED80 is a grab-and-go instrument.

A Compact 475mm Tube for Portability and Stability

The telescope has a tube length of 475mm (18.5 inches), or 381mm without the dew shield. The outer tube diameter is 100.7mm.

Explore Scientific's catalog lists its Hybrid Finder Scope Base for the FCD100 series, designed to accept legacy Explore Scientific finder brackets and mini dovetail-type finder brackets. A finder scope is not included.

Two Core Components: The FCD100-0806-02 OTA and ES-FF2F5/F7 Flattener

This bundle has two components. You receive the Explore Scientific ED80-FCD100 Air-Spaced Triplet Apochromat Refractor (FCD100-0806-02) and the Explore Scientific Field Flattener for f/5 to f/7 Refractors (ES-FF2F5/F7). The flattener is designed for refractors from f/5 to f/7.

Your First Night with the 480mm f/6 Refractor

First, attach the Vixen-style dovetail to a compatible equatorial mount and balance the 3.4 kg telescope. Next, insert the flattener's 2-inch barrel into the focuser, and then connect your camera with a T-ring and spacers to give 55mm (+/- 2mm) of spacing.

After performing a polar alignment on your mount, point the telescope to a bright star and achieve a sharp focus, for example with a focusing mask. Once focused, slew to your desired deep-sky target, such as the Orion Nebula (M42) or the Pleiades (M45), and begin your imaging sequence.