Varrow Halcyon 254 Dobsonian, with Dobsonian base

Specifications

Description

The Halcyon 254 is a 10-inch Newtonian reflector with a 254 mm parabolic mirror and a 1,200 mm focal length, giving a focal ratio of f/4.7. It shares the tube length of the 8-inch model in the same line, so the eyepiece stays at a comfortable height while the aperture grows by more than half in light-gathering area.

The 254 mm mirror collects about 13 times as much light as a 70 mm refractor and about 1.6 times as much as a 200 mm mirror. That extra light shows in the details of galaxies: the spiral structure of M51, the dust lane of NGC 4565, and the brighter members of the Virgo galaxy cluster under dark skies. Globular clusters resolve to their cores on good nights.

At f/4.7, collimation needs more care than in slower reflectors. The Halcyon 254 has a center-marked primary mirror and tool-free collimation knobs, so you can align it from the eyepiece end in a few minutes. Wide-field eyepieces show some coma near the edge of the field at this focal ratio, which a coma corrector removes.

The 2 in dual-speed Crayford focuser holds heavy eyepieces and has a fine-focus knob for planetary work. A fan behind the primary mirror helps the 254 mm mirror reach the outdoor temperature, which takes about 45 to 60 minutes on a cold night without it.

The tube weighs 14 kg and the base about 15 kg. Both fit in a mid-size car, but the tube is bulky, so plan how you carry it from storage to your observing spot. Many observers keep a 10-inch Dobsonian in a garage or shed close to where they observe.

About this configuration

The Varrow Halcyon 254 Dobsonian is offered in several configurations, and the notes below describe what this particular combination adds or changes. The Dobsonian rocker base keeps the telescope low and stable, and you aim it by pushing the tube gently by hand. The base and the tube separate for transport, which makes the telescope easier to carry out of the house in two trips. The carbon fiber tube expands less as the temperature drops, so the focus point drifts less as the night cools.

The deep-sky kit adds a wide-field eyepiece and a UHC filter for emission nebulae such as the Lagoon and the Orion Nebula. This is the 2026 edition, the most recent version of the Halcyon line in the catalog. Check the specifications table for the optical figures, since they stay the same across every configuration of the Halcyon line.

What's in the box

• Optical tube with 254 mm parabolic primary mirror
• Primary mirror cooling fan with battery holder
• 8x50 right-angle finder with bracket
• 2 in to 1.25 in adapter
• Collimation cap
• Dobsonian rocker base with altitude bearings
• 24 mm wide-field eyepiece (1.25 in)
• UHC nebula filter (1.25 in)

Compatibility notes

• Accepts 2 in and 1.25 in eyepieces, filters, and coma correctors.
• The tube fits the matching Dobsonian base; the tube-only version needs tube rings and a mount rated for at least 22 kg.
• A coma corrector designed for f/4 to f/5 Newtonians sharpens stars at the edge of wide fields.