Panasonic S1R has a Leica L lens mount and currently there are 76 native lenses available for this mount.
The latest released lenses that are compatible with the S1R are the Sigma 500mm f5.6 DG DN OS Sports, the Sigma 15mm f1.4 DG DN Art and the Panasonic S 28-200mm f4-7.1.
S1R also has a sensor based image stabilization system that is up to 6.0-stops effective which means that all of these lenses will be stabilized when used on the 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