ASKAR 71F Quadruplet Flat-Field Apochromatic Refractor Telescope

The ASKAR 71F is a compact quadruplet apochromatic refractor designed for both astrophotography and visual observing. With a 71mm aperture, 490mm focal length, and a native focal ratio of f/6.9, it offers a well-balanced combination of portability, image quality, and ease of use.

Designed for Full-Frame Imaging

The ASKAR 71F features a self-flattened optical design, supporting a 44mm image circle. This allows full-frame cameras to achieve sharp, well-corrected stars across the entire field without the need for an additional field flattener. Back-focus calculations are simplified, reducing setup complexity and overall system cost.

The quadruplet air-spaced APO lens assembly incorporates one element of ED glass, effectively controlling chromatic aberration while maintaining high contrast and colour fidelity.

Practical and Lightweight Design

The ASKAR 71F OTA weighs just 2.5kg, with a total packaged weight of 3.0kg including tube rings and dovetail plate. Its compact size and retractable dew shield make it easy to transport, store, and deploy in the field.

Visual Observing and Imaging Ready

The ASKAR 71F is supplied with accessories that allow immediate use for visual observation as well as astrophotography. Included are an 8mm eyepiece (60×), a 20mm eyepiece (25×), and a 1.25" 45° erecting prism, making the telescope suitable for terrestrial observation, birdwatching, and landscape viewing.

Both eyepieces feature standard 1.25" barrels with rubberised eyecups for comfortable use. The erecting prism provides correctly oriented images, avoiding inverted or mirrored views.

Imaging Connectivity

A photographic extension tube is included, offering M48×0.75 and M54×0.75 adapters, along with a built-in 2" filter thread. This allows direct connection to DSLR and dedicated astronomy cameras without additional adapters.

Mechanical Design and Focuser

The ASKAR 71F is manufactured using high-precision CNC machining. Internal surfaces are treated with matte black coating to minimise stray light and internal reflections. The retractable dew shield further improves portability.

The telescope is equipped with a 2.4" dual-speed rack-and-pinion focuser, featuring a 1:10 fine-focus reduction and a 360° rotatable rear section with engraved scale markings for precise framing and camera orientation.

A finder base slot is integrated into the handle, with additional finder bases on both sides of the focuser for flexible accessory mounting.

Specifications

Diagrams and Technical References

EAF Compatibility (Optional)

Optical Performance