Ricoh GXR P10 28-300mm has a lens mount and currently there are 0 native lenses available for this mount.
The latest released lenses that are compatible with the GXR P10 28-300mm F3.5-5.6 VC are the Nikon Micro-60mm f2.8D, the Carl Zeiss Makro-Planar T2/50 and the Carl Zeiss Makro-Planar T2/50.
GXR P10 28-300mm F3.5-5.6 VC also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on the GXR P10 28-300mm F3.5-5.6 VC.
Since Ricoh GXR P10 28-300mm has a Small Sensor sensor, it has a focal length multiplier of 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 GXR P10 28-300mm F3.5-5.6 VC.
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Ricoh GXR P10 28-300mm Lenses with Image Stabilization
Ricoh GXR P10 28-300mm Lenses with Weather Sealings