Askar FRA400 FRA500 F3.9 Reducer

Askar FRA400 FRA500 F3.9 Reducer

Description

The Askar F3.9 reducer is a dedicated optical accessory designed for the Askar FRA400 and FRA500 astrographs. It further reduces the original 400 mm focal length and f5.6 focal ratio of the FRA400 to a resulting focal length of 280 mm and a focal ratio of f3.9. This reduction effectively shortens exposure times while maintaining suitable coverage for astronomical imaging.
The reduction factor is 0.7x. The mechanical back focus is standardized at 55 mm, allowing easy integration with common imaging setups. The reducer features a built-in M48x0.75 filter thread, enabling direct use of 2 inch filters without additional adapters.
This reducer provides a straightforward solution for enhancing the imaging performance of FRA400 and FRA500 astrographs in astrophotography applications.

Technical specifications

• Compatibility: Askar FRA400, Askar FRA500

• Reduction factor: 0.7x

• Resulting focal length: 280 mm

• Resulting focal ratio: f3.9

• Back focus: 55 mm

• Filter thread: M48x0.75

• Primary use: astrophotography

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