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Apertura 25mm Extension Ring with M117 Threads - RC1025

Apertura 25mm Extension Ring with M117 Threads - RC1025 - Main image
$21.86 $29.95 In stock

Category: Telescope Accessories

Apertura 25mm Extension Ring
with M117 Threads

This Apertura 25mm Extension Tube is designed for the GSO 10" Ritchey-Chretien Astrograph, but it will also work with the GSO 12" RC or any product that accepts M117 threads. It is meant to be placed between the telescope and the focuser to extend back focus by 25mm. You can stack different lengths of extension rings to achieve the back focus you require for your imaging set-up. With an extension added at this location, you won't have to extend the draw tube as far, which will minimize downward tilt with heavy loads.

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Customer Reviews (5.0 / 5 · 5 reviews)

Robert N. ★★★★★

Exactly what I needed to dial in the back focus on my RC setup. The M117 threading engaged smoothly and the 25mm length solved my spacing issue perfectly.

Jacob ★★★★★

The threads are clean and precise, so the ring screws onto my RC telescope without any wobble. Finally got perfect spacing for my imaging train, sharp stars corner to corner now.

Claire ★★★★★

I needed just a bit more back focus to reach prime focus with my camera, and this 25mm extension ring solved it perfectly. The M117 threads screwed on smoothly without any binding, and my images are now sharp across the whole frame.