Vixen Telescope Extender PH

Vixen Telescope Extender PH
Vixen Telescope Extender PH
Vixen Telescope Extender PH
Vixen Telescope Extender PH
Vixen Telescope Extender PH
Vixen Telescope Extender PH


Suggested retail price: Contact local dealer

The best focal extender designed for Newtonian telescopes for serious astrophotography.

It is a high-quality made-in-japan focal extender lens for serious astrophotography. The Vixen Extender PH works with the optical surface of a parabolic mirror to correct coma aberrations on the Newtonian telescopes. It can transform an R200SS reflector into a research-grade F/5.6 astrograph with no false color, which is excellent characteristics of the Newtonian telescopes.

Vixen Telescope Extender PH Description

  • It extends the focal length by 1.4 times while correcting coma aberrations.

    The Extender PH not only extends the focal length of the R200SS from 800mm to 1120mm (1.4 times) but also excellently corrects coma aberrations inherent in Newtonian reflectors.

  • A wide 44mm image circle covers a full-frame imaging sensor.

    The image circle of the Extender PH covers a full-frame DSLR with a 35mm image sensor format (36 mm × 24 mm). It achieves sharp star images throughout the photographic field of view.

  • Ultimate light transmission AS coatings for extremely high contrast images.

    The same anti-reflection AS coatings that are renowned for surprisingly high light transmission (99.9% per surface) on our high-end VSD100F3.8 are provided on each of the lens surfaces of the Extender PH. Besides, the matte-finish is elaborate to eliminate internal reflections and loss of light. Note: Use the R200SS together with a Wide photo adapter 60DX, and a Light baffle hood is recommended to get the most out of it.

  • Stunningly sharp images if used with the R200SS.

    The Extender PH can be fit on any of our R200SS reflectors sold in the past. If you possess the R200SS already, you will be able to change it into an F/5.6 astrograph of high performance with the Extender PH. It provids a wide illuminated field of view with no dimmer images at the edges of the field of view, and the coma correction is perfect throughout the image circle. It is available for visual observation with an addition of an eyepiece adapter.

  • Usable as a BarLow Lens.

    The Extender PH works as a Barlow Lens by attaching to a 50.8mm visual back to the R200SS. You will obtain sharp images without coma in both visual observing and astrophotography. (The coma correction with this product is effective in any of parabolic mirrors theoretically.)

  • Spot diagrams (Comparisons with Vixen coma correctors.)

  • Sample image 'The Dumbbell Nebula' and sizes of camera sensors.

  • Visual and Photographic Configurations


Extender PH

  • Magnification
  • Focal length
    R200SS: 800mm (F4) to 1120mm (F5.6)
  • Optical coatings
    AS coatings (More than 99.9% light transmission per surface)
  • Construction
    4 elements in 3 groups
  • Image circle
  • Thread diameter and thread pitch
    M56mm, 0.75mm (male), or fits to 50.8mm visual back
  • Filter size
  • Visual observing
    Possible with an optional Eyepiece adapter
  • Dimensions and weight
    56mm x 128mm long, 245 g


  • Extender PH
  • EX Tube 66


For availability of products, please contact our local dealers. The specifications are subject to change without notice.

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