Askar 91F 0.75x Reducer
169.00
Tax included 
Delivery times depending on the shipping method: Switzerland: 2 to 3 days; Europe: 7 to 10 days.
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Askar 91F 0.75x Reducer
The Askar 91F 0.75x is a dedicated optical reducer for the Askar 91F refractor, designed to lower the focal ratio to f5 and enhance astrophotography efficiency.
Askar 91F 0.75x Reducer
Description
The Askar 91F 0.75x reducer is specifically optimized for the Askar 91F refractor to unlock greater astrophotography capabilities. Once installed, it reduces the effective focal length to 455 mm and the focal ratio to f5. This faster focal ratio provides a wider field of view and shorter exposure times, making it suitable for imaging nebulae, star clusters, and faint or fast-moving celestial objects.
The reducer also incorporates field correction. Its optical design is based on a triplet lens structure that supports a 44 mm image circle. The standard back focus is 55 mm, measured from the base of the M48 male thread, ensuring straightforward integration with common imaging setups.
Both front and rear threads use the M59x1 standard. The Askar 91F photographic extension tube, supplied with M54x0.75 and M48x0.75 adapters, allows direct and convenient connection. The reducer also features an integrated M48x0.75 thread for direct use of 2 inch filters.
Manufactured using CNC machining, the reducer offers a refined finish. Front and rear threaded metal caps protect the optics from dust when not in use. With a total weight of 0.3 kg, it remains compact and well balanced on the optical tube.
Technical specifications
Compatibility: Askar 91F
Reduction factor: 0.75x
Resulting focal length with 91F: 455 mm
Resulting focal ratio: f5
Optical design: triplet
Image circle: 44 mm
Back focus: 55 mm from M48 male thread base
Front thread type: M59x1
Rear thread type: M59x1
Filter thread: M48x0.75
Weight: 0.3 kg
Manufacturing: CNC machining
Protection: front and rear metal threaded caps
Askar Réducteur 91F 0.75x
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Askar 91F 0.75x Reducer
The Askar 91F 0.75x is a dedicated optical reducer for the Askar 91F refractor, designed to lower the focal ratio to f5 and enhance astrophotography efficiency.