Baader Hyperion® Aspheric 2" eyepiece 31mm

Aspherical eyepieces:
Normally, light rays close to the edge are refracted more strongly towards the center when passing through a lens than light rays close to the axis. As a result, the image field of an uncorrected system can become blurred towards the edge. The aspherical correction of an optical system now corrects numerous imaging errors at once. Sharpness is achieved over the entire field of view, distortion is reduced to a minimum and the eyepiece can be made much smaller and lighter.

The eyepieces are supplied with 1¼" and 2" receptacles

Baader 2" Aspheric eyepieces in use
Aspheric 2" eyepieces compete against the world's best large field eyepieces and offer convincing advantages. Higher star limit size, unsurpassed color fidelity, low weight and an attractive price.

The eyepiece design includes aspheric lens surfaces, which are now standard in the most modern camera lenses, to offer the best imaging performance over the entire field of view in the smallest possible space.The Aspheric eyepiece design allows fewer glass surfaces to be used and, in combination with the extreme quality of the Phantom Group multi-coating, an Aspheric eyepiece delivers a brighter, higher-contrast image than even wide-angle eyepieces with spherical lenses that are twice as expensive.

At 72 degrees, the Aspheric field of view is only slightly larger than the largest angle of view of the human eye (68 degrees). This allows you to see the entire star field at once without having to "roll" your eyes. Many wide-angle eyepieces offer an impressive field of view of 80 degrees and more, but this cannot be viewed all at once and the available light is distributed over too large an image area so that ultimately the image brightness (= star limiting magnitude) and contrast are wasted.

The larger the angle of view of a wide-angle eyepiece, the more difficult it is for the eyepiece designer to create a good viewing behavior.

Extreme wide-angle eyepieces, but also wide-angle eyepieces with a simple lens design, often have a very "nervous" viewing behavior. If the eye is moved very slightly forwards and backwards or sideways, the field of view disappears immediately. Especially when working with students, guests or at public observatories, such a nervous eyepiece is a frustrating experience, because the observer cannot make use of the excellent data from the telescope.

In a direct comparison, all observers find that an Aspheric eyepiece shows finer stars and fainter structures in gas nebulae than much more expensive 2" wide-angle eyepieces. The technological progress here is particularly dramatic.

Photographic adapter threads for all types of projection photography:
Photographically, all common DSLR camera bodies with and without a Lens, as well as CCD cameras, can be screwed directly behind the eyepiece using the M43 or SP 54 system thread on the eye side. There is also a huge selection of adapter threads and adapter rings to choose from. This means that the telescope focal length can be changed almost at will if small star fields or planetary objects are to be documented with high resolution. Detailed instructions are included with each eyepiece.

System suitability for projection photography:
Photographic adapter threads for all types of projection photography
Afocal projection photography with Baader Aspheric eyepieces
Each Aspheric eyepiece is equipped with screw threads on both sides so that it can be permanently installed in an optical beam path as a projection system.

On the telescope side, there is a 2" SC thread in the eyepiece body which allows the eyepiece to be firmly attached to the end of the tube, for example.For example, the eyepiece can be firmly screwed onto the tube end of all Schmidt Cassegrain optics without a receptacle and without a star diagonal mirror.

Visually, this extremely short attachment type enables a larger true field of view than any wide-angle eyepiece with a 2" receptacle.

Bi-ocular stereoscopic observation with Aspheric eyepieces:
Aspheric eyepieces are the only long focal length wide angle 2" eyepieces that can also be attached to astro binoviewers in both eyes. In addition to the 2" receptacle, each 2" Aspheric eyepiece therefore comes with a 1.25" receptacle with 2" SC thread, which allows the Aspheric eyepiece to be inserted into any telescope binoviewer. The minimum eye relief should not be less than 56mm.

Baader Phantom Coating® Group:
Baader Phantom Group Coating is a 7-layer broadband antireflection coating with extremely low residual reflection. The designation "Group" indicates that the most effective anti-reflection coating system has been calculated for each individual glass type of the lenses used in the Hyperion eyepieces.

All these different anti-reflective coatings on each individual glass surface have been optimized to be most effective where the human eye has its highest night sensitivity - at around 520 nm - in the green part of the spectrum.

The best anti-reflective coating appears almost colourless: this proves that the anti-reflective coating is equally effective across the entire visible spectrum. Phantom Group anti-reflective coatings are - depending on the type of glass - almost completely colorless. This ensures that the least amount of light is lost for the night-adapted eye and that no stray light can occur.

If a coated lens (eyepiece or Lens) shows a strong green reflex when viewed directly from the front, then it is not a Baader Phantom Group antireflection coating! The intense green reflection is an indication of a less complex coating technique and it means that the most light is reflected, i.e. lost, in the spectral range between 500-550 nm.

Technical data

Manufacturer: Baader Planetarium
Net weight (kg): 0.40
Hyperion eyepiece series

Eyepiecedesign
Anti-slip protection: Classic Undercut
Number of lens elements: 6
Number of lens groups: 4
Outer diameter (mm): 59.5 mm
Field diaphragm diameter: 38 mm (2"), 30mm (1¼")
Field diaphragm offset to reference surface: +/- 0 mm
Height 1¼" receptacle: 23.9 mm
Height 2" receptacle: 27.5 mm
Eyepiece height above reference surface: 76.7 mm

Features
Eye relief (mm): 17 mm
Focal length: 31 mm
Field of view: 72°
Optical design: Aspherical
Parfocal: Yes
Specialty: classic eyepiece projection
Insertion dimension (inches): 1¼", 2"
Coating (anti-reflective): Phantom Coating® Group

Accessories included
Eyecups: foldable eyecup (M43)
Dust caps: 1¼" dust cap (31.8mm), 2" dust cap (45mm), 2" dust cap (46.5mm)

Connections
Filter thread: Yes
Camera thread: M43SP54