This particular lens is equipped with auto focus to give you the best setting for each picture. It is not a prime lens, but rather a zoom lens.
Tamron 18-300mm F/3.5-6.3 Di III-A VC VXD Lens for Sony E APS-C Mirrorless Cameras (Black)
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Tamron 18-300mm f/3.5-6.3 Di III-A VC VXD Lens for Sony E
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Tamron 18-300mm F/3.5-6.3 Di III-A VC VXD Lens for Sony E-mount