Askar 91F 0.75× Reducer This 0.75× reducer is designed specifically for the Askar 91F. Its triplet design corrects the photographic field across a 44 mm full-frame image circle. With the matched telescope, Askar publishes 455mm focal length and f/5.
Manufacturer model: Askar 91F 0.75× Reducer · Specifications checked against manufacturer data on 2026-11-04
This 0.75× reducer is designed specifically for the Askar 91F. Its triplet design corrects the photographic field across a 44 mm full-frame image circle. With the matched telescope, Askar publishes 455mm focal length and f/5.
Optical configuration
Reduction widens the photographed field and lowers the focal ratio while providing field correction. It is a matched optical accessory, rather than a universal reducer for other telescope models.
Connections and filters
The optical unit has M59×1 at both ends of optical unit. It works with the 91F photographic extension assembly, whose M54×0.75 and M48×0.75 adapters provide the camera connection. The built-in M48×0.75 thread accepts a 2-inch filter.
Sensor spacing
Set 55 mm from the base of the M48 male thread to the sensor. This reference applies to the stated M48 camera arrangement; changing the adapter changes the reference face. Include all intervening adapters and optical components when arranging the train.
Construction and storage
The CNC-machined housing has threaded metal caps at both ends for dust protection during storage. The manufacturer technical table lists a weight of 0.3kg. Telescope, camera and filters are separate equipment.
Askar 91F 0.75× Reducer This 0.75× reducer is designed specifically for the Askar 91F. Its triplet design corrects the photographic field across a 44 mm full-frame image circle. With the matched telescope, Askar publishes 455mm focal length and f/5.
Manufacturer model: Askar 91F 0.75× Reducer · Specifications checked against manufacturer data on 2026-11-04
