Panasonic S5 has a Leica L lens mount and currently there are 66 native lenses available for this mount.
The latest released lenses that are compatible with the S5 are the Sigma 14mm F1.4 DG DN, the Sigma 17mm F4 DG DN C and the Sigma 50mm F2 DG DN C.
S5 also has a sensor based image stabilization system that is up to 6.5-stops effective which means that all of these lenses will be stabilized when used on the S5.
Since Panasonic S5 has a Full frame sensor, it has a focal length multiplier of 1x so lenses will provide their original focal length on S5.
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Panasonic S5 Lenses with Image Stabilization
Panasonic S5 Lenses with Weather Sealings