Askar F3.9 Reducer for FRA600

Askar F3.9 Reducer for FRA600

Description

The Askar F3.9 is a 3 inch optical reducer specifically designed for the Askar FRA600 astrograph. Its optical construction is based on a four element design optimized for this instrument. With a 0.7x reduction factor, it effectively lowers the focal ratio and reduces the resulting focal length to 420 mm.
This reduction shortens exposure times and increases the usable sky area, providing greater flexibility for both visual observation and astrophotography.
The mechanical back focus is standardized at 55 mm, allowing straightforward integration with common imaging setups. The reducer features a built in M48x0.75 filter thread, enabling direct attachment of 2 inch filters without additional adapters. This design ensures practical operation and compatibility with standard astronomical accessories.

Technical specifications

• Compatibility: Askar FRA600

• Reduction factor: 0.7x

• Resulting focal length with FRA600: 420 mm

• Resulting focal ratio: f3.9

• Optical design: four elements

• Mechanical diameter: 3 inch

• Back focus: 55 mm

• Filter thread: M48x0.75

• Use: visual observation and astrophotography