Eyepiece Projection OPFA VII with M36.4 thread

Eyepiece Projection OPFA VII with M36.4 thread

Description

The OPFA VII eyepiece projection adapter with M36.4 thread is a fully integrated projection system for telescopes using a female M36.4 mm thread, commonly found on Vixen, Takahashi, and Lichtenknecker instruments. It enables high-magnification planetary or lunar imaging using digital or analog SLR cameras with removable lenses. Based on the OPFA IV core unit, it includes a dedicated M36.4-thread adapter (#1508039) for a rigid and precisely centered connection.

The system consists of the OPFA sliding focuser, two 40 mm T-2 extension tubes, and the M36.4 adapter on the telescope side. The adapter screws directly into the telescope’s M36.4 female thread, creating a light-tight, vibration-free connection. A 31.75 mm projection eyepiece (not included) is inserted into the focuser, which allows fine axial adjustment to set the correct projection distance.

This distance, combined with the eyepiece’s focal length, determines the equivalent focal length (fE) according to the formula:
fE = fprimary × ((a ÷ fEP) - 1)
where a is the projection distance and fEP is the eyepiece focal length. Increasing the projection distance or decreasing the eyepiece focal length results in higher magnification.

The two supplied 40 mm T-2 extension tubes connect the sliding focuser to the camera’s T-2 ring (not included), and additional T-2 extensions can be added to increase the projection ratio. The entire setup is light-tight and mechanically stable.

The integrated locking ring allows the camera to be rotated freely to achieve optimal framing, even in systems like OPFA VII where the telescope-side connection is rigid and non-rotatable.

The internal diameter of 38 mm accommodates standard eyepieces without significant vignetting. All components are precision-machined to ensure solid and stable imaging performance, even with long exposures. The system is fully compatible with Baader’s Astro T-2 accessories.

Requires a 31.75 mm projection eyepiece (not included)
Requires a camera-specific T-2 ring (not included)

Technical specifications

• Compatible with Vixen, Takahashi and Lichtenknecker telescopes with M36.4 female thread

• Telescope-side connection: M36.4 male thread (via adapter #1508039)

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

• Internal connection: T-2 female thread (M42 x 0.75)

• Sliding focuser for 31.75 mm eyepieces

• Fine axial adjustment of projection distance

• Locking ring for stepless camera orientation

• Includes two 40 mm T-2 extension tubes

• Internal diameter: 38 mm

• Outer diameter: 60 mm

• Optical length: variable depending on configuration

• Net weight: 0.16 kg

• Light-tight, rigid, play-free construction

• Compatible with Baader Astro T-2 extension system

• Ideal for high-magnification planetary and lunar imaging