Baader Hyperion 68° 5mm Modular Eyepiece - 1.25" & 2"

The Baader Hyperion 5mm is a modular eyepiece. Its native focal length is 5mm, but this can be altered by unscrewing the front lens element (the part inside the 1.25" barrel) and adding optional Baader Fine Tuning Rings (FTRs) between it and the main eyepiece body. For example, adding a 14mm and a 28mm FTR together converts it to a 2.6mm eyepiece, providing much higher magnification without needing a separate Barlow lens.

For eyepiece projection with a DSLR, you need two main accessories. First, the Baader Hyperion M43/T-2 Adapter (#2958080), which screws onto the eyepiece's M43 thread (found under the rubber eyecup). Second, you need a T-Ring specific to your camera's brand (e.g., Canon EOS, Nikon). This combination creates a secure, threaded connection for high-magnification imaging.

Baader's 7-Layer Phantom Group Coating is a broadband anti-reflection coating. Each layer is calculated for a specific glass type within the eyepiece's 8-element design and is optimized for maximum light transmission at approximately 520nm, the peak sensitivity of the dark-adapted human eye. This results in higher contrast and image brightness with very low residual reflection.

Magnification is the telescope's focal length divided by the eyepiece focal length. On a telescope of 1000mm focal length, the 5mm gives 200x; with the 14mm and 28mm fine tuning rings together (2.6mm) the same telescope gives about 385x. The exit pupil is the eyepiece focal length divided by the telescope's focal ratio.

Yes, in two ways. The 1.25" barrel is threaded for standard 1.25" filters. Additionally, the M48 thread exposed when you unscrew the 1.25" barrel (to change focal lengths) can be used to install a 2" filter inside the optical path. This not only adds filtration but also modifies the focal length, acting as another step in the modular system.

Both are for connecting cameras, but for different imaging methods:

• M43 Thread: This is the smaller thread used for eyepiece projection. It adapts to the common T2 thread (M42x0.75) and is ideal for cameras where the lens is removed (like DSLRs or dedicated astronomy cameras).
• SP54 Thread: This is a larger thread used for afocal projection. It is designed for cameras where the lens cannot be removed, such as point-and-shoot cameras or camcorders, using specific adapter rings.

The long 20mm eye relief is a significant comfort feature, especially for a high-power eyepiece. It means you can hold your eye 20mm away from the eye lens and still see the entire 68° field of view. This is particularly beneficial for observers who wear eyeglasses, as it allows them to keep their glasses on while observing without losing any of the view.

When you open the Hyperion 5mm to change its focal length, you may notice a special coating on some internal, non-optical surfaces. This is a "dust adhesive layer" designed by Baader. Its purpose is to trap any dust particles that may enter the eyepiece body, preventing them from settling on the lens surfaces and ensuring the optics remain clean over the long term. It should not be touched or removed.

The winged rubber eyeshield of the Hyperion 68° eyepieces is ideal for binocular use. A binoviewer needs a pair of eyepieces of the same focal length.

The front lens group is designed to provide sharp images across the entire field for visual use. While removing it is recommended for some afocal imaging setups to increase the camera's field of view, using the eyepiece without this front group for visual observation will result in a noticeable loss of edge sharpness. For the best visual views, the eyepiece should always be used with its front lens group attached.