The Takahashi 645 Super Reducer is a 0.72x focal reducer for the CCA-250 corrected-Cassegrain astrograph. The 645RD reducer has a large image circle of 60mm, making it suitable for use with medium format sensors. The 0.72x reduction factor reduces the focal length to 890mm and focal ratio to f/3.6, transforming the CCA-250 into a high performance super 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%. The lenses are coated with broad-spectrum multi-layer coating, reducing reflections and increasing transmission over the visible range.
Spot diagram of Takahashi CCA-250 with 645 Super Reducer CA 0.72x focal reducer.
|Optical design||4 lenses in 4 groups|
|Reduction factor||0.72 x|
|Image circle||60 mm|
|Connection telescope side
||Screwed directly to CAA TKP86200
|Connection camera side
||M72 x 1 male