Fujifilm GFX 50S has a Fujifilm G lens mount and currently there are 18 native lenses available for this mount.
The latest released lenses that are compatible with the GFX 50S are the Fujifilm GF 110mm F5.6 TS Macro, the Fujifilm GF 30mm F5.6 TS and the Fujifilm GF 55mm F1.7R WR.
Fujifilm GFX 50S doesn't have a sensor based image stabilization system but
4 of these lenses already comes with optical image stabilization.
Since Fujifilm GFX 50S has a Medium format sensor, it has a focal length multiplier of 0.79x 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 GFX 50S.
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Fujifilm GFX 50S Lenses with Image Stabilization
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