5mm Focal Length, 68° Apparent AFOV, For 1.25" and 2" Focusers

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The Ultima Duo 5mm Eyepiece with T-Adapter Thread from Celestron features a 68° apparent angular field of view, eight fully multicoated optical elements arranged in five groups and packaged in a rubberised aluminium barrel which fits 1.25" and 2" focusers. While fully multicoated optics increase light transmission and delver brighter images with better contrast compared to similar optics with fewer coatings, blackened lens edges reduce ambient light and image blurring. This optical design is specifically aimed at viewing and imaging of bright astronomical objects.

This eyepiece is meant to be used easily for both viewing and astrophotography. To serve both of these goals, the eyepiece has a 20 mm long eye relief with fold-down eyeguard and a T-adapter thread for your DSLR or astronomical CCD camera. When you find a perfect view and ready to take a photo, simply take off the rubber eyeguard and use the 42mm threads on top of the eyepiece to connect your camera with optional T-ring.

The Ultima Duo eyepiece is compatible with most telescopes and includes protective cups and a carrying pouch.

Key Features

Optical Performance

  • 5mm focal length
  • 68° apparent angular field of view
  • Fully multicoated optics increase light transmission and contrast
  • 20 mm eye relief allow use with glasses
  • Blackened lens edges prevent stray light
  • For imaging bright celestial bodies
  • 8 elements in 5 groups


  • Compatible with 1.25" and 2" focusers
  • Compatible with most telescopes without extra adapters
  • Can be used with planetary imagers Skyris or NexImage via a T-to-C adapter


  • Fold-down rubber eyeguard allows use with glasses
  • 42 mm thread under the eyeguard allows quickly attaching DSLR or CCD with an optional T-adapter
  • Anodised aluminium barrel is threaded for 1.25" filters and has a safety recess
  • Rubberised rings allow for a non-slip grip while wearing gloves


Focal Length
Barrel Diameter
1.25" / 2"
Eye Relief
20 mm
Lens System
8 elements in 5 groups
Filter Diameter
Field Stop Diameter
Not provided by manufacturer
Apparent Field of View
Length: 3.5 - 4.7" (90 - 125 mm)
Diameter: 2.4" (60 mm)
Not provided by manufacturer
Celestron Ultima Duo 5mm Eyepiece with T-Adapter Thread (1.25" and 2")
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