Halden Ridgeline 114 Dobsonian, tube only

Specifications

Description

The Ridgeline 114 Dobsonian is a Newtonian reflector mounted on a simple altazimuth base. Its 114 mm parabolic primary mirror gathers light for a focal length of 912 mm, which gives a stated focal ratio of f/8. At that ratio, coma is small at moderate powers, and the eyepiece stays at a workable height when the tube points near the zenith.

The optical tube carries a 31 mm minor-axis secondary mirror on a four-vane spider, which leaves a central obstruction of about 27 percent of the aperture. The primary mirror sits in a cell with three collimation screws, and the tube weighs 4.6 kg with the focuser and finder in place. A 2 in dual-speed rack-and-pinion focuser carries a star diagonal and a heavy eyepiece without slipping.

The Dobsonian base uses a plywood rocker box with a PTFE-on-laminate bearing surface, so the tube moves smoothly in altitude and azimuth without a drive. Assembly takes about thirty minutes, and the rocker box comes in two pieces for storage. Because the mount is manual, you will need to nudge the tube to follow the sky, and the 6x30 finder helps you locate targets before you move to the eyepiece.

Typical targets include the Moon, where the terminator shows craters and mountain ranges at high power; Jupiter, with its equatorial belts and the four Galilean moons; Saturn, with its rings at moderate power; and the Double Cluster in Perseus, which fits in one field with a 2 in eyepiece. Under dark skies, the tube also shows the brighter globular clusters such as M13 and the Orion Nebula, although the nebula will show more structure with a larger aperture.

About this configuration

This listing covers one specific configuration of the Halden Ridgeline 114 Dobsonian, defined by its bundle, finish, accessory kit, and edition year. This is the optical tube on its own, so you need to supply a mount that can carry its weight steadily. Without a mount in the package, check the tube weight against the payload rating of your mount, with some margin to spare. The gloss white tube reflects sunlight, which helps it stay closer to air temperature while you set up before dusk.

This configuration comes without extra accessories, so budget for at least one more eyepiece if you are starting out. The optics in the 2024 edition match the other years; the changes concern hardware details only. The optical figures in the specifications table apply to this configuration and to every other version of the Halden Ridgeline 114 Dobsonian.

What's in the box

• Optical tube with 31 mm secondary mirror and four-vane spider
• Dobsonian rocker box in two pieces
• 6x30 finder scope with bracket
• 2 in dual-speed focuser with 1.25 in eyepiece adapter
• Collimation tool
• Front and rear dust caps

Compatibility notes

• Accepts 2 in eyepieces directly and 1.25 in eyepieces through the supplied adapter.
• The rocker box is sized for this optical tube and does not fit other Halden tubes.
• The finder bracket fits the supplied 6x30 finder only.