Askar f/3.9 reducer for FRA400 and FRA500 flatfield astrograph

The ASKAR 0.7x full format focal length reducer improves the aperture ratio of the FRA 400 and FRA 500 from f/5.6 to f/3.9 and thus halves the exposure time

♦ The reducer offers a corrected image field up to full format

♦ Screw connection via the M68x1 thread on the focuser

♦ The focal length is reduced from 400 mm to 280 mm or from 500 mm to 351 mm for a larger field of view

♦ Working distance 55 mm from the M48x0.75 connection thread

♦ 2" filter thread is available on the connection adapter - the connection adapter has an M58x0.75 thread

Note: The telescope is not included in delivery.


 
Askar F3.9 full frame focal reduction
The new full-frame reducer F3.9 from Askar reduces the effective focal length of the telescope by a factor of 0.7x. The original f/5.6 apo becomes a fast f/3.9 apo. Your exposure time will be significantly shorter, reduced to around 50%. The field of vision becomes significantly larger.

Designed for use with the FRA400 and FRA500 flatfield refractor, the FRA400Red provides good correction with these telescopes even when using full-frame sensors. The working distance from the M48x0.75 thread to the camera sensor is 55 mm. The camera adapter is equipped with a 2" filter thread.