Panasonic S1R has a Leica L lens mount and currently there are 53 native lenses available for this mount.
S1R also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on S1R.
Since Panasonic S1R has a Full frame sensor, it has a focal length multiplier of 1x so lenses will provide their original focal length on S1R.
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Panasonic S1R Lenses with Image Stabilization
Panasonic S1R Lenses with Weather Sealings