Eyepiece Projection OPFA III with 2" nosepiece

Eyepiece Projection OPFA III with 2" nosepiece

Description

The OPFA III eyepiece projection adapter with 2" nosepiece is a complete optical projection system designed for planetary or lunar photography using digital or analog SLR cameras with removable lenses. It is specifically made for Schmidt-Cassegrain telescopes by Celestron and Meade that feature a standard 2" threaded rear cell.

This model includes the OPFA base, a sliding focuser with locking ring, two 40 mm T-2 extension tubes, and a 16 mm ultra-short 2" internal-threaded adapter (#2958500B) that connects directly to the telescope's 2" SC thread. This rigid screw-on connection ensures precise axial alignment without play or flexure.

The assembly begins at the telescope side with the 2" nosepiece, followed by the sliding focuser that holds a 31.75 mm projection eyepiece (not included). The sliding focuser allows fine adjustment of the eyepiece position to control the projection distance. Two included 40 mm T-2 extensions help to set the distance between eyepiece and camera sensor, directly influencing the projection magnification according to the formula: fE = fprimary × ((a ÷ fEP) - 1). By adding more T-2 extensions from the Astro T-2 system, very large projection scales can be achieved, even for CCD imaging.

The integrated locking ring allows for stepless camera rotation, providing flexible image framing, especially important in OPFA models 3 to 7 where the telescope-side connection is fully threaded and cannot rotate independently.

All connections use T-2 threads (M42 x 0.75), ensuring maximum compatibility with camera T-rings. The 38 mm internal diameter supports standard eyepieces with minimal vignetting. The entire construction is designed to be both light-tight and mechanically stable, preventing image shift during long exposures or high-magnification setups.

This system is supplied without a projection eyepiece or camera T-ring. It is a professional, modular solution for advanced users looking to implement classical eyepiece projection with Schmidt-Cassegrain telescopes and cameras featuring removable lenses.

Technical specifications

• Telescope compatibility: Celestron and Meade Schmidt-Cassegrain with 2" thread

• Telescope-side connection: 2" SCT male thread, T-2 female thread (M42 x 0.75)

• Camera-side connection: T-2 male thread (M42 x 0.75)

• Internal clear aperture: 38 mm

• Outer diameter: 60 mm

• Optical length: variable depending on configuration

• Net weight: 0.18 kg

• Includes: OPFA base, sliding focuser with locking ring, two 40 mm T-2 extensions, short 2" internal-thread nosepiece

• Eyepiece not included (requires 31.75 mm)

• Camera T-ring not included

• Adjustable projection via sliding focuser and extension tubes

• Rigid, light-tight construction

• Compatible with digital or analog cameras with removable lenses

• Works with additional Astro T-2 system extensions