TAKAHASHI 645RD REDUCER FOR FSQ-106EDX4

The Takahashi 645RD Reducer is a 0.72x focal reducer for the FSQ-106EDX4 Petzval Quadruplet refractor. The 645RD reducer has a large image circle of 60mm, making it suitable for use with medium format sensors. The 0.72x reduction factor transforms the FSQ-106EDX4 into a fast 380mm f/3.6 widefield astrograph.

The 645RD Reducer consists of four large-diameter lenses in four groups, giving illumination of more than 70% at the edge of the field. The illumination over a 44mm diagonal (such as that of a full-frame sensor) is more than 90%, nearly 50% greater than the QE 0.73x reducer.

While the QE 0.73x reducer shows slight violet chromatic aberration around 420nm, the 645 Reducer completely corrects this. Additionally, the diffraction spot size is two-thirds that of the QE 0.73x reducer at the edge of a 44mm field. The lenses are coated with broad-spectrum multi-layer coating, reducing reflections and increasing transmission over the visible range.