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

The ED80 Essential Bundle: An 80mm f/6 Imaging Platform

This package is engineered as a complete optical solution for the wide-field astrophotographer. It pairs the highly-regarded ED80 Essential Series optical tube with the field flattener Explore Scientific designed for f/5 to f/7 refractors, which lists the ES-ED0806-02 among the telescopes it fits. The bundle is built for observers who want to capture expansive deep-sky targets like the vast nebulosity in Cygnus.

The core of the system is a portable, high-contrast apochromatic refractor that is as capable visually as it is for imaging. However, by including the field flattener, this bundle directly addresses the primary challenge of imaging with fast refractors: field curvature. It is an ideal starting point for an imager moving up from a camera lens or a doublet refractor, and it serves as a perfect lightweight, wide-field companion for an experienced astronomer who already owns a larger, narrow-field instrument.

Air-Spaced Triplet Optics: HOYA FCD1 Glass for Apochromatic Views

The ED80 Essential refractor uses a three-lens, air-spaced objective design to deliver true apochromatic performance. One of the key elements is made from HOYA FCD1, a premium extra-low dispersion (ED) glass that provides excellent color correction. The air-spaced triplet design virtually eliminates the chromatic aberration, or "purple fringing," that can plague less-corrected telescopes.

The practical result is higher contrast and sharpness. On bright targets like the Moon, planets, or bright stars, you will see crisp, well-defined details without distracting color halos. For deep-sky imaging, this means star colors are rendered accurately, and fine details in nebulae and galaxies are not washed out by unfocused light. Explore Scientific's proprietary EMD enhanced multi-layer deposition coatings are on all optical surfaces of the ED80 Essential.

80mm Aperture at f/6: Wide-Field Views and 3.4 kg Portability

With an 80mm aperture and a 480mm focal length, the ED80 operates at a native focal ratio of f/6. This "fast" optical system gathers light quickly, allowing you to capture significant detail on faint objects with shorter exposure times compared to a slower f/8 or f/10 telescope. This focal ratio also produces a wide field of view, making it perfectly suited for framing large celestial objects.

Weighing only 3.4 kg, the optical tube assembly (OTA) is exceptionally portable. This "grab-and-go" nature makes it easy to transport to dark-sky locations and set up quickly. Its low weight and compact 475mm length mean it does not require a large, expensive equatorial mount, further enhancing its appeal as a portable imaging rig or a high-quality travel scope for visual astronomy.

Included Field Flattener: Correcting Curvature from f/5 to f/7

A natural characteristic of refractor telescopes is field curvature, where the focal plane is not perfectly flat. While often unnoticeable visually, this becomes apparent in astrophotography, causing stars at the edge of the frame to appear elongated or comatic. This bundle includes a dedicated field flattener specifically designed to work with refractors in the f/5 to f/7 range, making it a perfect match for the ED80's native f/6 optics.

The flattener has a 2-inch barrel that slides into the focuser, fully multi-coated optics and 38 mm of clear aperture, and sits between the telescope and the camera. It corrects the curved focal plane so stars stay sharp toward the edges of the frame. The flattener does not change the telescope's 480mm focal length or f/6 focal ratio. It is a photographic-only accessory and is not intended for visual use.

Camera Connection: Achieving the Required 55mm Back Focus

To function correctly, the included field flattener requires 55 mm (+/- 2 mm) of spacing between the flattener and your camera's sensor. This 55mm distance is a common standard in astrophotography, and most equipment is designed around it. The flattener terminates in a male M42x0.75 T2 thread, which is the standard "T-thread" used on most astronomy cameras and DSLR/mirrorless T-rings.

• DSLR Cameras: A standard T-ring for your camera model usually comes close to the 55mm spacing. Mirrorless cameras have a shorter flange distance and need extra spacers.
• Dedicated Astronomy Cameras: Many dedicated cameras are supplied with spacers that let you build up 55mm; check your camera maker's figures.

If your imaging train includes other accessories like an off-axis guider or a filter wheel, you may need to purchase additional M42 T2 extension rings of various lengths to precisely reconstruct the 55mm distance.

The 2" Rack-and-Pinion Focuser

The ED80 Essential Series is equipped with a 2" rack-and-pinion focuser. This traditional and reliable design provides a stable platform for holding both visual accessories and an imaging train. The 2" drawtube can accept 2" diagonals and eyepieces for wide-field visual observation, or it can be stepped down to 1.25" with an optional adapter. For imaging, the 2" barrel of the included field flattener slides directly into the focuser.

The telescope also includes extension tubes for the focuser. These are used to ensure that you can reach focus with a variety of different equipment combinations, from cameras to different eyepiece and diagonal setups.

Mounting the 3.4 kg OTA: Vixen Dovetail and Mount Requirements

The ED80 comes with a Vixen-style dovetail. This is the most common mounting standard for small-to-medium sized telescopes, ensuring compatibility with a wide range of commercially available equatorial mounts. At a light 3.4 kg, the optical tube itself is not demanding on a mount.

For astrophotography, a stable German equatorial mount with accurate tracking is essential. Add the camera and accessories to the 3.4 kg tube and choose a mount whose imaging capacity comfortably exceeds the total. For visual use, the ED80 can be used on a lighter-duty equatorial mount or even a robust alt-azimuth mount for quick, casual observing.

Visual Observing with the ED80 Essential Triplet

While this bundle is optimized for imaging, the ED80 is also a superb visual instrument. To use it for visual observing, simply remove the field flattener. Insert a 2" star diagonal and an eyepiece; eyepieces are not part of this package. Once outfitted for visual use, the apochromatic optics provide stunning, high-contrast views of a wide variety of celestial objects.

The 480mm focal length is perfect for low-to-medium power sweeping of the Milky Way's star fields, open clusters like the Pleiades (M45), and large nebulae. With higher magnification eyepieces, it delivers crisp views with virtually no false color of the Moon's craters, Jupiter's cloud belts and moons, and the rings of Saturn. Its portability makes it an excellent scope to take to a star party or on a camping trip.

Mechanical Build: Dew Shield, Rings, and Hybrid Finder Base

The ED80 Essential is built for durability and practical use in the field. The optical tube is protected by a retractable dew shield, which helps to prevent moisture from forming on the objective lens during long nights and also blocks stray light from entering the optical system. The telescope carries a Vixen-style dovetail for mounting.

A Hybrid Finder Scope Base comes pre-installed on the scope. This versatile base is designed to accept both legacy Explore Scientific finder scope brackets and the more common mini-dovetail type used by many other manufacturers. This makes it easy to attach your preferred finder scope or red-dot finder for easy object location.

What's in the Box: A 2-Piece Imaging Bundle

This package is streamlined for the astrophotographer and contains the two core optical components needed for wide-field imaging. It is designed to be integrated with your existing camera and mount system. Eyepieces are not included.

The bundle includes the ED80 Essential Series optical tube assembly, complete with its 2" rack-and-pinion focuser, extension tubes, and the pre-installed Hybrid Finder Scope Base. The second key component is the ES-FF2F5/F7 Field Flattener, which is matched to the telescope's focal ratio.

First Night Out: Your First 5 Steps to Imaging

Getting started with the ED80 imaging bundle is a straightforward process. Assuming you have a suitable equatorial mount, a power source, and your chosen camera, here is a basic workflow for your first session.

1. Mount and Balance: Attach the ED80 OTA to your mount via its Vixen dovetail. Attach your camera and any other accessories to the telescope, then carefully balance the entire assembly in both Right Ascension and Declination. This is critical for accurate tracking.
2. Polar Align: Perform a precise polar alignment on your equatorial mount. Accurate polar alignment is the foundation of long-exposure astrophotography.
3. Connect the Imaging Train: Insert the field flattener into the telescope's focuser. Thread your camera (with any necessary spacers to achieve 55mm back focus) onto the flattener's T2 threads.
4. Find and Frame Your Target: Use a finder scope or your mount's GoTo system to slew to a bright star. Use the focuser to achieve a sharp focus, ideally with the aid of a Bahtinov mask. Then, slew to your intended deep-sky target and frame the object as desired.
5. Begin Imaging: Start your imaging sequence. The ED80's fast f/6 optics will allow you to capture impressive data even with relatively short sub-exposures.