Sony A55 has a Sony/Minolta Alpha lens mount and currently there are 143 native lenses available for this mount.
The latest released lenses that are compatible with the A55 are the Lensbaby Sol 45 DSLR, the Venus 105mm F2 and the Lensbaby Burnside 35.
A55 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on the A55.
Since Sony A55 has a APS-C sensor, it has a focal length multiplier of 1.5× 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 A55.
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Sony A55 Lenses with Image Stabilization
Sony A55 Lenses with Weather Sealings