Tamron 20mm f/2.8 Di III OSD M1:2 - Sony E-mount

The Tamron 20mm f/2.8 Di III OSD M1:2 is an ultra-wide prime for Sony E-mount full-frame cameras. Similar to others in this series, it offers a 1:2 reproduction ratio for close-up work, combined with a broad field of view ideal for architecture and interiors. It features a 67mm filter thread—consistent with much of Tamron's mirrorless line—and employs LD and aspherical elements to reduce distortion and chromatic aberrations. When buying a used copy, ensure the autofocus is smooth, as the OSD motor moves the entire optical group and can be slower than linear motor designs. SDS checks for any physical damage to the filter thread and ensures the mount contacts are clean for reliable communication with Sony bodies. Verify that the rear element is free from dust, as wide-angle lenses can be sensitive to internal debris at small apertures.