Explore Scientific ED152 152mm f/8 Triplet Carbon Fiber Refractor Telescope

The Explore Scientific ED152 (item TED15208CF-HEX33) is a 152 mm f/8 air-spaced triplet with HOYA FCD1 extra-low dispersion glass in a carbon fiber tube that weighs 20.5 lb, so it suits lighter equatorial mounts such as the Losmandy G11 PMC-Eight. Beside Sky-Watcher's Esprit 150EDX, a 150 mm f/7 triplet with FPL-53 glass, the aperture is close to a tie. The Esprit's 1050 mm focal length frames more sky on a given camera; the ED152's 1216 mm gives more image scale, and it ships with a 2-inch diagonal, which Sky-Watcher does not include with the Esprit.

Key Features

• Optics. The HOYA FCD1 element sits between two other air-spaced elements, a design rated as diffraction-limited and apochromatic, with EMD enhanced multi-layer coatings on all optical surfaces and a multi-point collimation cell, collimated in Explore Scientific's quality control department before shipping.
• Light grasp. The 152 mm objective gathers (152 ÷ 127)², about 1.4 times, the light of a 127 mm refractor and (152 ÷ 102)², about 2.2 times, that of a 102 mm.
• Carbon fiber tube. The carbon fiber optical tube is both strong and thermally stable. The tube runs 52 inches with the dew shield and 41 without; the shield ships reversed over the tube and fastens with three set screws.
• Focuser. A 3-inch two-speed focuser for fine focusing control.
• In the box. A 99% reflective 2-inch diagonal with a 1.25-inch adapter, cradle rings with a carry handle on a Losmandy-style dovetail, and a finder base.
• Imaging. Explore Scientific's 3" Field Flattener .7x Focal Reducer is designed for the f/8 system, gives 55 mm of back focus from its rear face, and turns 1216 mm at f/8 into about 851 mm at f/5.6 (1216 × 0.7).

Who It's For

• Imagers who want image scale. The ED152 is built for astrophotography and visual observing alike; 1216 mm of focal length suits galaxies and small nebulae, and the reducer widens the field when a target needs it.
• Visual observers who want 6 inches of refractor. Explore Scientific's eyepiece picks for this focal length are the 52° Series 40mm (30x), 52° Series 20mm (61x) and 72° ED Series 8.5mm (143x).
• Buyers weighing the Esprit 150EDX. Sky-Watcher gives the Esprit a 3.4-inch rack-and-pinion focuser with 11:1 fine focus, a rotatable focuser with a camera angle adjuster and a retractable dew shield, all points in its favor, along with tube rings, a D-style dovetail and a padded hard case. It includes no diagonal or finder, and its flattener is optional, as the ED152's correctors are. Sky-Watcher gives the tube's weight only with its accessories, 34 lb, so that figure is not a like-for-like match for the ED152's 20.5 lb tube assembly.
• Buyers choosing among Explore Scientific's refractors. The FCD100 127mm in carbon fiber has HOYA FCD100 glass at 952 mm and f/7.5, weighs 14 lb and carries a 2.5-inch hex focuser rated for 10 lb. The ED127 Essential is the 127 mm FCD1 triplet at f/7.5, and the AR152 is a 152 mm f/6.5 achromatic doublet at 23 lb. All three cost less.

Accessories & Compatibility

• Mount. Plan on a mount in the class of the Losmandy G11 PMC-Eight, and on a tripod or pier tall enough for a 52-inch tube near the zenith.
• Electric focusing. Explore Scientific's 3-inch Self-Centering Focuser fits the TED15208CF's back cell with no adapter. It is rated to lift 17 lb. Its draw tube is long enough to do without extension tubes, and it is compatible with popular after-market electric focusers.