The Houdini eyepieces provide around 19–20 mm of nominal eye relief, with a foldable eyecup that provides around 15 mm of effective eye relief. This is sufficient for many observers wearing glasses. However, some glasses wearers may still find that they need to get their eyes slightly closer to the eye lens to see the full field of view comfortably.
Replacing the rubber eyecup with a simple felt ring can increase the effective eye relief by about 1 mm by allowing glasses to rest closer to the eye lens. For observers who are only just short of being able to see the full field of view, this can make a noticeable difference.
The felt protects the glasses from direct contact with the metal housing of the eyepiece. The original rubber eyecup does not need to be discarded. If you want to observe without glasses, you can simply put the rubber eyecup back on top of the felt ring. There is no need to remove the ring.
Three Rings to rule them all
The rings are made from black, 0.5 mm self-adhesive felt, laser-cut to shape. Three different ring sizes are used for the Houdini eyepieces:
-
H30 / H20: 48 × 38 mm
-
H12: 42 × 35 mm
-
H9 / H7: 40 × 33 mm
Until October 4, we are making these felt rings available free of charge to Houdini users who would like to try them. Contact us by e-mail or via the Contact page.
We ship them in packs of 10, with 4× H30/H20, 2× H12 and 4× H9/H7 felt rings.
Installation
Installation is straightforward.
Remove the rubber eyecup and clean the surface if necessary. Peel off the backing paper from the self-adhesive felt ring and carefully stick the ring onto the flat surface around the eye lens.
The rings are only 0.5 mm thick and quite flexible. We have found that the easiest way to remove the backing paper is to lift a corner with the tip of a craft knife.
Clear skies!
Robert