Askar 91F The Askar 91F is a 91mm aperture refractor with a 609mm focal length at f/6.7. Its air-spaced quadruplet uses a front triplet and rear correcting element, including one ED element. The integrated optical design supports a 44 mm full-frame image circle.
Manufacturer model: Askar 91F · Specifications checked against manufacturer data on 2026-11-04
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The Askar 91F is a 91mm aperture refractor with a 609mm focal length at f/6.7. Its air-spaced quadruplet uses a front triplet and rear correcting element, including one ED element. The integrated optical design supports a 44 mm full-frame image circle.
Native imaging and visual use
Field correction is built into the telescope, so native photography does not need a separate flattener or a single mandatory flattener spacing. Attach the camera within the connection limits and focus. The table gives maximum and minimum connection distances for each rear adapter and focuser position. The 2-inch and 1.25-inch visual interfaces also accommodate observing accessories.
Focus, framing and filters
The 3-inch rack-and-pinion focuser provides coarse and 1:10 fine adjustment, plus a graduated 360° rotator. The photographic extension assembly offers M54×0.75 and M48×0.75 connections and an internal 2-inch filter thread.
Mounting and transport
Two finder bases and a finder-base slot in the handle provide accessory positions. The telescope includes tube rings and a 230 mm Vixen-style dovetail plate. Its retractable dew shield shortens the transport configuration. Lengths and weights below distinguish the visual and photographic arrangements and the bare OTA from mounting hardware.
Imaging mode: 75mm (from the base of M48×0.75 male thread） 93mm（from the base of M54×0.75 male thread); Observing mode: 112mm（from the end of 1.25" eyepiece holder） 122mm（from the end of 2" eyepiece holder）
Raccordement min. d'accessoires porte-oculaire sorti
Imaging mode: 45mm (from the base of M48×0.75 male thread） 63mm（from the base of M54×0.75 male thread); Observing mode: 82mm（from the end of 1.25" eyepiece holder） 92mm（from the end of 2" eyepiece holder）
Askar 91F The Askar 91F is a 91mm aperture refractor with a 609mm focal length at f/6.7. Its air-spaced quadruplet uses a front triplet and rear correcting element, including one ED element. The integrated optical design supports a 44 mm full-frame image circle.
Manufacturer model: Askar 91F · Specifications checked against manufacturer data on 2026-11-04
