Tamron filed a patent discussing optical designs of 16-70mm F4 zoom lens for 35mm full-frame mirrorless cameras.
Tamron 16-70mm f/4 Patient
[Public number] Japanese Patent Application Laid-Open No. 2021-67805 (P2021-67805A) click here
[Publication date] April 30, 3rd year of Reiwa (2021.4.30)
[Title of Invention] Zoom Lens and Imaging Device
Focal length: 16.4867 35.0004 67.8794 mm
F number: 4.1174 4.1076 4.1432
Half angle of view (degree): 53.8837 29.8398 16.1054
The 16-70mm is a very common lens in the APS-C world, but for full-frame cameras this focal length is quite unusual. However, some people may like the standard zoom that extends to such an ultra-wide-angle range.