Tamron corresponds to a less full-size mirror 28-70mm F3.5-5.6 of patent is being filed. Take a look at the patent details translated by Japanese language
Description, self-interpretation of the patent literature
- Patent Publication No. 2016-90745
- Published 2016.5.23
- Filing date 2014.10.31
- Example 1
- F-number = 3.61 The ~ 5.00 to 5.77
- Focal length = 28.91 ~ 44.97 ~ 67.84mm
- Half angle of view (ω) = 37.95 ~ 25.86 ~ 17.64 °
source – egami
see more patents from Tamron