Askar F3.9 Full Frame Reducer for Askar FRA600 telescopes
Askar provides a brand-new F3.9 full frame reducer for FRA600 astrograph, further reducing the focal length and thus shortening the exposure time on its original 600 mm focal length and f/5.6 focal ratio design basis. The reduction factor is 0.7×, which can satisfy most deep-sky astrophotography. The back focus is standard 55mm. The reducer has built-in M48×0.75 thread, easy for the attachment of 2" filters.
The Askar 3 inch F3.9 full frame reducer features 4 elements optical design specifically for the FRA600, offers a 0.7X reduction in focal ratio, when used with the FRA600 astrograph, this reducer effectively shortens the exposure time, its focal length is reduced to 420MM, dramatically increases your field of view and bringing more convenience and possibilities for your visual use or astrophotography. The back focus is the standard 55MM. It also has a built-in M48X0.75 (2 inch) filter thread that allows you to screw on filters conveniently.
- Correction Optics Type
- Field Flattener