The Askar 91F Flat-Field is a versatile quadruplet APO refractor designed for both visual observation and astrophotography. With its 91mm aperture, 609mm focal length, and native f/6.7 focal ratio, this self-flattening optical system delivers excellent performance without the need for additional field flatteners or complex backfocus calculations.
The Askar 91F features a sophisticated four-element optical design (three elements in the front and one in the rear), including one piece of ED glass to effectively reduce chromatic aberration. The self-flattened design eliminates the need to calculate back focus or purchase additional flatteners – simply attach your camera and start imaging. This supports full-frame sensors up to 44mm with excellent edge-to-edge star performance.
Despite its impressive optical capabilities, the 91F maintains a compact and lightweight form factor. The OTA weighs just 3.92kg, with a total weight of 4.52kg including tube rings and dovetail plate. The retractable dew shield further reduces overall length for improved portability.
The 91F is equipped with a dual-speed 3-inch rack-and-pinion focuser featuring 1:10 fine adjustment for precise focus control. A 360° scaled rotator at the rear end allows for accurate angle adjustment during imaging sessions.
Unlike many telescopes that require separate accessory purchases, the 91F comes with everything you need to get started:
Whether for deep-sky astrophotography, planetary observation, birdwatching, or travel photography, the Askar 91F is your ideal companion for exploring both the cosmos and the natural world. The rear interface includes both 2" and 1.25" adapters for compatibility with a wide range of astronomical accessories.