Orion Flip Mirror Eyepiece Barrel Extender

Orion Flip Mirror Eyepiece Barrel Extender

This webpage documents construction of an eyepiece barrel extender for an Orion flip mirror. The eyepiece barrel extender increases the distance between the eyepiece and the helical focuser, allowing both the imaging camera and eyepiece to achieve focus. The extender required about 10 min. to fabricate and cost less than $5 USD.

Orion Flip Mirror with Eyepiece Focus Problems

I purchased an Orion flip mirror to simplify framing with my Cannon Digital Rebel T3 (EOS 1100D) DSLR camera (below photo). Unfortunately when my DSLR camera was focused, there was not enough extension in the helical eyepiece focuser to achieve focus with any of my eyepieces. Holding the eyepiece barrel just outside the helical focuser gave a good image. I decided to fabricate an extender to increase the distance between the eyepiece and the flip mirror.

Eyepiece Barrel Extender

The eyepiece barrel extender is fabricated from a small section of black plastic tube, a scrap of stainless steel plate, and two band clamps. The plastic tubing is exactly the same outer diameter as a standard 1.25" eyepiece barrel. I cut a strip of steel plate and covered the perimeter with electrical tape to eliminate sharp edges. I wrapped the steel plate around the end of the plastic tube and clamped it in place with one of the band clamps (this clap fastens together the metal and plastic sections). The below left photo shows the eyepiece end of the extender. The eyepiece barrel fits into the steel section and rests on the plastic tube. The other band clamp fits around the end of the metal section and secures the eyepiece (below right photo).

The below photos show the flip mirror with the eyepiece and barrel extender. This was a very simple and inexpensive modification, and completely solved the focusing problem. I will eventually try to find a small band clamp with a thumb screw to simplify switching eyepieces.


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