Olympus E-PL9 has a Micro Four Thirds lens mount and currently there are 121 native lenses available for this mount.
The latest released lenses that are compatible with the E-PL9 are the Rokinon 7.5mm f3.5 Fisheye, the Samyang 7.5mm F3.5 Fisheye MFT and the OM System 90mm F3.5 Macro.
E-PL9 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on the E-PL9.
Since Olympus E-PL9 has a Four Thirds sensor, it has a focal length multiplier of 2x 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 E-PL9.
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Olympus E-PL9 Lenses with Image Stabilization
Olympus E-PL9 Lenses with Weather Sealings