Vixen 31.7mm Prism Diagonal – 90° Viewing Angle for Comfortable Stargazing & Terrestrial Viewing Through Your Telescope (ES3675)

A 90° Prism Diagonal for Comfortable Viewing Near the Zenith — For Refractors and Cassegrains

Without a diagonal, looking straight through a refractor or Cassegrain aimed high in the sky means craning your neck awkwardly downward. This prism diagonal (the angled piece that bends the light path 90°) lets you look at a comfortable right angle to the telescope tube, so you're looking sideways or downward into the eyepiece instead of straight back.

It uses a glass prism rather than a mirror to redirect the light, which gives clean, bright views without the slight light loss of a mirror diagonal. Images are erect (right-way up) but left-right reversed — normal for visual astronomy and irrelevant for most observing, though worth knowing if you're trying to match a star chart to the view.

Not compatible with reflector telescopes (Newtonian, Dobsonian, etc.) — refractors and Cassegrains only. Cannot be used with a flip-mirror diagonal.

Who This Is For

• Refractor and Cassegrain owners who want a comfortable 90° viewing angle for objects high in the sky
• Anyone upgrading from a lower-quality plastic diagonal or replacing a lost one

Specs