SkyWatcher Tetra 80ED Quadruplet APO

The Sky-Watcher Tetra 80ED is a four-element apochromatic astrograph built around two elements of HOYA glass - one FCD100, one FCD1 - in a quadruplet design that corrects colour and field curvature in the objective itself. There is no separate flattener to space, tilt or misplace: the telescope focuses a flat, colour-corrected 44mm field straight onto a full-frame sensor.

At 80mm of aperture and 400mm of focal length it works at f/5, fast enough for short sub-exposures on wide targets while staying at a focal length that is forgiving to guide. Every air-to-glass surface is fully multi-coated, and the 1:10 rack and pinion focuser gives the fine control needed to hold focus at this focal ratio.

The optical tube and lens hood are carbon fibre, which keeps the whole assembly at 4.1 kg including the camera adapter and holds focus better through a falling night temperature than an aluminium tube of the same size. A (D-Style) dovetail plate is fitted for mounting.

Unusually for an astrograph, the Tetra 80ED arrives ready to observe as well as image: a 2in dielectric-coated diagonal, a 70 degree ultra wide 20mm eyepiece and an 8x50 finderscope are all in the box.

Key Features:

Four-Element Apochromatic Optical System

HOYA FCD100 and FCD1 Glass

Flat 44mm Full-Frame Field

80mm Aperture and 400mm Focal Length

1:10 Rack and Pinion Focuser

Carbon Fibre Optical Tube and Hood

What's in the Box:

SkyWatcher Tetra 80ED Quadruplet APO

Optical Tube Assembly

Diagonal

Eyepiece

Finderscope

Mounting

Focuser