The ubiquitous AP2.7 inch thread has become an astronomy industry standard thanks to the tireless efforts of Roland and his team at Astro-Physics. Optec has produced an extension set and a few new adapters in an effort to extend this industry standard. Optec's AP 2.7-inch extension tubes feature female threads on one end with male threads on the opposite end
AP 2.7 Extension Tubes with knurled bases to help attach and detach these tubes. The extensions can be combined and stacked. We believe our four and five piece sets will provide all the needed extensions for fixed focal length telescopes with 1/4" (6.35mm) increments using a minimum number of pieces.
All extensions and mounts are made from high-strength 6061 aluminum alloy and black anodized. Anti-reflection threading and internal baffles on the largest extension tube help minimize internal reflections. All internal surfaces are painted and baked with a non-reflecting ultra-flat black paint.