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Hyperion Focal Reducer


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Second-generation design optimized for new-style Hyperion 12.5" and 16" models. Available now.

The optical design of the Hyperion focal reducer has been revised to take advantage of the longer mechanical backfocus available on the truss-tube versions of the Hyperion telescopes. The backfocus of the reducer now allows use of Apogee high-cooling camera bodies with filter wheel and MonsterMOAG guider. Also, the focal reduction factor has been improved, allowing a wider field of view and faster imaging.

This focal reducer has been custom-designed to match the excellent optical performance of the Hyperion astrograph. It retains a large, flat field, free from aberrations. In fact, performance is diffraction-limited over a full 52mm field of view.

With 4 inches of backfocus, the Hyperion focal reducer works with a variety of camera setups, including:

  • Apogee Alta Series*
  • Apogee Alta Series* with FW50 filter wheel
  • Apogee Alta Series* with FW50 and MonsterMOAG guider
  • Apogee Aspen Series
  • FLI Proline
  • FLI Proline with FLI CFW
  • QSI 500 Series
  • SBIG ST Series
  • SBIG STL Series
  • SBIG STL Series with FW8 filter wheel
  • SBIG STL Series with FW8 and MonsterMOAG guider
  • SBIG STX Series
  • Starlight Xpress SXVR
  • And many more...

* Including deep-cooling models

The focal reducer converts the 12.5" f/8 Hyperion to an f/5.7 focal ratio, and the 16" f/7.3 Hyperion to an f/5.2 focal ratio, making each nearly 2 times faster. The reducer is designed to cover a 52mm image circle, corresponding to the diagonal size of the popular KAF-16803 large-format CCD sensor. Large (76mm) lens elements keep the vignetting to less than 15% over the 52mm field.

The Hyperion focal reducer threads onto the end of the telescope's standard Feathertouch 3.5" focuser, in place of the normal end cap. A 3" flange forms the standard camera attachment. The Apogee Alta series with Apogee FW50 and Astrodon MonsterMOAG bolts directly to the flange. Other cameras require alternate adapters or spacers to keep the backfocus correct and keep the performance nominal. Adapters are available for a variety of cameras.

Hyperion 12.5" Specifications with Focal Reducer

  • Focal Ratio: f/5.7
  • Focal Length: 1825mm
  • Optimal Field of View: 52mm (1.63 degrees)
  • Average RMS Spot Diameter (52mm FOV): 5.6 microns

Hyperion 16" Specifications with Focal Reducer

  • Focal Ratio: f/5.25
  • Focal Length: 2132mm
  • Optimal Field of View: 52mm (1.4 degrees)
  • Average RMS Spot Diameter (52mm FOV): 6.7 microns

General Specifications

  • Focal reduction factor: 0.72x
  • Total Backfocus (from lens to focal plane) = 112.5mm
  • Fully AR coated, less than 0.5% reflectance over 400-700nm
  • Weight (with standard 3" flange): 2.1 lbs (955g)
  • Overall length (with standard flange): 3.35" (85mm)
  • Main body diameter: 3.47" (88mm)
  • Maximum diameter (focuser mount): 4.4" (112mm)
  • Made in USA

Performance Diagrams

RMS Spot Size vs. Field

Vignetting Plot

First Light Image

LRGB = 120:30:30:30 minutes with Apogee U16M camera