Pentax 645D has a Pentax 645AF2 lens mount and currently there are 6 native lenses available for this mount. Pentax 645D doesn't have a sensor based image stabilization system but 2 of these lenses already comes with optical image stabilization.
Since Pentax 645D has a Medium format sensor, it has a focal length multiplier of 0.8× so you have to multiply lenses original focal length with this multiplier to find the Full Frame equivalent focal length of the lens when mounted on 645D.
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Pentax 645D Lenses with Image Stabilization
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