Baader Hyperion 68° 8mm Eyepiece - 1.25"/2"

An 8-Element, 68° Apparent Field Optical System

The 8mm focal length gives high magnification on any telescope; magnification is the telescope's focal length divided by 8. The 68° apparent field is the same for every eyepiece in the series, which Baader sums up as ease of view even at high magnifications.

This optical system uses 8 lens elements arranged in 5 groups to maintain sharp views across the field. Eye relief is 20mm and the field stop diameter is 9.5mm (Baader technical data).

Phantom Group Coatings: 7 Layers for Maximum Contrast

Baader's proprietary Phantom Coating® Group is a 7-layer broadband anti-reflection system applied to every air-to-glass surface. Baader optimised these coatings to be most effective where the night-adapted eye is most sensitive, at about 520 nm in the green region of the spectrum.

A strong green reflex shows light between 500 and 550 nm being reflected and lost, while Phantom Group coatings appear almost colourless, showing an equally good effect across the visible spectrum. The aim is that the least amount of light is lost for a night-adapted eye, without stray light.

Dual 1.25" and 2" Barrels

The Hyperion 8mm fits 1.25" and 2" focusers and star diagonals. The 1.25" barrel, which holds the first group of lenses, fits a 1.25" holder; the 2" barrel above it fits a 2" holder.

• Filter Threads: The 1.25" barrel accepts standard 1.25" (M28.5) filters. The M48 thread revealed when the 1.25" barrel is removed can be used to mount 2" filters.
• Slip protection: Both the 1.25" and the 2" barrel have a classic undercut.

Variable Focal Lengths From 8mm Down to 4.3mm

A defining feature of the Hyperion series is its modularity. By unscrewing the 1.25" barrel, which contains the first lens group, you can insert Baader's optional Fine Tuning Rings (FTRs) to change the eyepiece's effective focal length. This allows you to achieve multiple magnifications from a single eyepiece without using a Barlow lens, which adds extra glass to the light path.

With the 8mm Hyperion, you can achieve the following focal lengths:

• 8mm: Native focal length.
• 6.9mm: Achieved by inserting a Baader 2" eyepiece filter (6mm height) between the main body and the 1.25" barrel.
• 6.0mm: Achieved by adding a 14mm Fine Tuning Ring.
• 5.0mm: Achieved by adding a 28mm Fine Tuning Ring.
• 4.3mm: Achieved by adding both 14mm and 28mm Fine Tuning Rings.
• 21.8mm: The focal length when used as a 2" eyepiece with the front lens group (1.25" barrel) completely removed for low-power afocal imaging.

Integrated M43 & SP54 Threads for Projection Imaging

All Hyperion eyepieces are suitable for afocal and classical eyepiece projection. Removing the rubber eyecup and thread-protecting ring reveals two distinct system threads for securely attaching a camera.

• M43 Thread: This thread is intended for classical eyepiece projection. Using the Baader Hyperion M43/T-2 adapter ring (#2958080), the Baader Astro T-2 System adapters for Moon and planetary photography can be used, and any T-2 camera ring with an SLR or DSLR camera may be attached. With the 5mm and 8mm focal lengths the highest projection magnifications are easily attained.
• SP54 Thread: The larger SP54 thread is designed for afocal projection, where the camera's lens cannot be removed (e.g., point-and-shoot cameras, camcorders). Baader offers a range of Hyperion DT-Rings to connect the SP54 thread directly to the filter threads on the front of a camera lens, with a minimum of separation distance, for example the DT-rings SP54/M28 (#2958028) and SP54/M37 (#2958037) with the Hyperion 11mm extension ring (#2958090).

Binocular Use, Eye Cap and Parfocal Group

The winged rubber eyeshield of the Hyperion 68° eyepieces is ideal for binocular use. The rubber eye cap can be stored folded down, especially for persons who wear glasses, or folded up. The body has an outer diameter of 58mm and weighs 370g; the drawing gives 67.8mm for the body above the reference plane and 24mm for the 1.25" barrel.

Baader's technical data lists the 8mm in the parfocal group of the series (the 24mm is the exception). Baader asks that the eyepiece only be opened at the M48 thread at the top of the 1.25" barrel; other joints are secured with Loctite, and disassembly elsewhere voids the warranty.