Askar FRA400C 0.7x Full-Frame Reducer

Product Overview

The Askar FRA400C 0.7x Full-Frame Reducer is the dedicated reducer for the Askar FRA400C astrograph. It changes the FRA400C system to 280mm focal length at f/3.9 while maintaining full-frame imaging support and a standard 55mm back focus.

Who Is This Product Best For?

This reducer is best for FRA400C owners who want faster exposures, a wider field of view, and a more efficient deep-sky imaging setup for large nebulae, star clusters, and wide-field targets.

Why Choose This Product?

• Dedicated optical reducer for the FRA400C.
• 0.7x reduction changes the FRA400C to 280mm at f/3.9.
• Triplet reducer design with flat-field correction.
• Supports full-frame imaging when correctly spaced.
• M48x0.75 rear thread with built-in 2-inch filter thread.

Recommended Uses

• Wide-field deep-sky astrophotography.
• Large emission nebulae and star fields.
• Full-frame and APS-C camera setups on the FRA400C.
• Faster imaging sessions where shorter exposure times are helpful.

Compatibility and Accessory Notes

This reducer is designed specifically for the Askar FRA400C. It uses an M48x0.75 rear-end adapter and provides a standard 55mm back focus measured from the base of the M48 male thread. The built-in M48x0.75 filter thread supports standard 2-inch mounted filters.

Important Limitations

• Designed for the FRA400C; do not assume compatibility with other telescopes.
• Requires correct 55mm camera spacing for best performance.
• Not useful for visual observing; this is primarily an imaging accessory.
• The FRA400C telescope and camera adapters are not included.

Frequently Asked Questions

Is this good for beginners?

Yes, for FRA400C owners who already understand basic camera spacing. Beginners should be careful to set the 55mm back focus correctly.

What is it best used for?

It is best used for faster wide-field deep-sky imaging with the FRA400C.

Does it work with full-frame cameras?

Yes, the vendor specifies full-frame imaging support when used with the FRA400C and correct spacing.

Does it require additional accessories?

Most imaging setups will still require the correct camera adapter or spacer combination to reach 55mm back focus.

Our Recommendation

Ontario Telescope recommends this reducer for FRA400C owners who want the fastest, widest-field configuration available for that telescope. Do not choose it for visual-only use or for telescopes other than the FRA400C unless compatibility is confirmed.