Was able to do a side by side comparison to the AF speed of the PZ1650 vs SEL35F18.
(Note that the PZ1650 support Phase Detect AF while the SEL35F18 only works on Contrast Detect 'at the moment'. I have 2 Nex 5R both set at the same setting)
Test Condition:
-Test took place indoors in low light. Auto-ISO will set from 1600 to 3200.
-Random panning from a close subject, mid distant subject, to a far distant subject.
-I held the two Nex 5R. One on each hand, vertically. occasionally switching cameras from one hand to the other.
The PZ1650 at it's widest(16mm)
-PZ1650 focuses about 1/10th of a second faster than the SEL35F18. It's not that much but you will notice it when waiting for the beep sound of the AF.
PZ1650 set to 35mm F/5.6 and the SEL35F18 also set at F/5.6
-The SEL35F18 focuses almost just as fast as the PZ1650.
PZ1650 set to 35mm F/5.6 and the SEL35F18 set to "F/1.8"
-Now this really surprised me as the SEL35F18 would sometimes focus faster than the PZ1650!!
My conclusion:
The PZ1650 obviously have the edge in AF speed at it's wider and widest setting vs the SEL35F18 but once set the PZ1650 to 35mm, the SEL35F18 is able to keep up with the AF Speed and sometimes even focus faster than the PZ1650 if the SEL35F18 is set to a brighter aperture setting.
P.S. I also tried comparing the SEL50F18 and SEL35F18 AF speed and the result is, The SEL50F18 is simply no match to the AF speed of the SEL35F18. The SEL50F18 would sometime autofocus 1 sec. to 1.5 sec slower than the SEL35F18. BUT I still find the SEL50F18 produces a little bit but noticeably sharper images over the SEL35F18.
*credits to TPCMAN of TPC