@Tuco, I have been playing with Lens Turbo focal reducer that does the offset of the 1.5 crop fact on APS-C sensor. LT have adapters for NEX and Fuji. Here is how it looks on the NEX with Super-Tak 35mm f/3.5 (a lovely lens). The beauty in the LT or the better (more expensive) one in Speedbooster lies in the gain of 1 stop of light and 0.72*1.5 final crop factor on the APS-C, essentially get you close to the FF FOV.
Not a great picture to show, I have your SuperTak 28mm f.3.5, the best part with the LT is gaining back the 28mm * 1.5 * 0.72 ~ 30.24mm FOV in FF and gain of one stop
shot
wide open with NEX 5N in f/3.5
with Lens Turbo
@Nester, thank you for your kind words.
@Jean, we share similar traits with LBA non-stop on Super/SMC Takumar and Tamron adaptall-2.
Cheers,
Hin