Specifications
Brand
Technical specs
Design and durability
Introduction:
- The 0.75X reducer can bring Askar 91F's focal ratio down to F5, providing not only a faster focal ratio but also built-in field-flattening correction. The shorter focal ratio delivers a wider field of view and a faster exposure time, making it ideal for capturing large areas of nebulae, star clusters, and faint, fast-moving celestial objects.
- The 91F 0.75X reducer adopts a triplet design and supports a 44mm full-frame image circle. The back focus from the M48 thread is a standard 55mm. Both end threads are M59x1. The 91F photographic extension tube includes M54x0.75 and M48x0.75 adapters for direct and convenient connection to the 0.75x reducer. The reducer features a built-in M48x0.75 2-inch filter thread, allowing for direct filter installation and use. The entire reducer is CNC-machined and comes with front and rear metal threaded caps to protect against dust when not in use.
Specification:
- (After attaching) 91F Focal length: 455mm
- (After attaching) 91F Focal ratio: f/5
- Lens Number: Triplet design
- Back Focus: 55mm (from the base of M48 male thread)
- Weight: 0.3kg
- Rear-end thread type: M59x1
Package Included:
- 1 x Reducer
Note:
- The ASKAR 91F is not included.





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