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
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.
Exact named-model manufacturer specification table and operating information checked. Unpublished values are not inferred.
90697
Scheda tecnica
Apertura
91mm
Paraluce
Retractable
Coda di rondine
230 mm Vixen-style
Correzione di campo
Integrated 3+1 optical system; no separate native flattener
Filettatura filtro
M48×0.75, 2-inch
Basi per cercatore
2
Rapporto della messa a fuoco fine
1:10
Focale
609mm
Rapporto focale
f/6.7
Focheggiatore
3-inch dual-speed rack-and-pinion
Corsa del focheggiatore
30mm
Maniglia
Finder-base slot
Cerchio d'immagine
44mm
Configurazioni di lunghezza
513mm(including 1.25" adapter as dew shield contracted） 599mm(including 1.25" adapter as dew shield fully stretched） 550mm(including the photographic adapter as dew shield contracted） 636mm(including the photographic adapter as dew shield fully stretched）
Dotazione standard del produttore
A 91F OTA，a pair of tube rings, a handle, a 230mm Vixen dovetail plate,a set of photographic adapters
Collegamento massimo accessori con focheggiatore rientrato
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）
Collegamento minimo accessori con focheggiatore esteso
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
