Halden Auric 20 mm wide-field eyepiece

Specifications

Description

The Auric 20 mm is a six-element wide-field eyepiece with a 60-degree apparent field and a 1.25 in barrel. Its focal length sits in the middle of the low-power range, so it frames large objects while still showing fine detail. It is a practical choice for telescopes between about 400 mm and 1,500 mm of focal length. In a 1,000 mm telescope it gives 50x with a true field of about 1.2 degrees, enough to fit the Double Cluster in Perseus within a single view.

Six elements arranged in a wide-field design keep the image flat toward the edge of the field. In telescopes slower than about f/5, stars stay round across most of the 60-degree view. Faster Newtonians may show some softening at the edge. All air-glass surfaces are multi-coated, and the barrel interior is blackened to reduce stray light. The optical train is sealed against dust, which helps maintain contrast over time in humid observing conditions.

A 20 mm eyepiece in an f/6 telescope produces an exit pupil of about 3.3 mm, which suits dark skies and extended objects such as open clusters and large nebulae. The field stop of 20.0 mm sets the true field, and the 16 mm of eye relief allows comfortable viewing for most observers, including many who wear glasses. The fold-down rubber eyecup blocks stray light when folded up and gives room for glasses when folded down. The threaded barrel accepts standard 1.25 in filters for narrowband or light-pollution work.

At 185 g, the Auric 20 mm balances well in most lightweight diagonals and does not load a focuser heavily. In a set of three or four eyepieces, it fills the gap between a 10 mm eyepiece and a 32 mm wide-field eyepiece, giving a useful step in magnification for scanning the Milky Way and locating targets before moving to higher power.

About this configuration

The Halden Auric 20 mm wide-field eyepiece is offered in several configurations, and the notes below describe what this particular one adds. This configuration comes without a case, which suits observers who keep their eyepieces in a shared foam box. No case is included, so the eyepiece ships in a simple box with its two dust caps fitted. A winged eyeguard helps you hold your eye at the right position, which makes the edge of the field easier to see.

Titanium gray shows dust and fingerprints less than black, and it keeps a uniform look over time. The optics in the 2024 edition match the other years; the changes concern the housing only. The true field in your telescope is roughly the apparent field divided by the magnification you reach with this eyepiece.

What's in the box

• Eyepiece with fold-down rubber eyecup
• Top and bottom dust caps
• Padded storage case
• Winged rubber eyeguard

Compatibility notes

• Fits any 1.25 in focuser, diagonal, or Barlow lens.
• The barrel accepts standard 1.25 in filters.
• Sharp across most of the field at f/5 and slower; softer at the edge in faster Newtonians.