There are 10 examples in the patent. The shortest focal distance goes from 16.46mm to 16.52mm. The longest focal distance goes from 48.35mm to 48.83mm. Maximum aperture is always f/2.9. Image circle is APS-C (radius = 14.24mm).
Five examples include 16 elements in 13 groups. Three examples include 17 elements in 13 groups. Two examples include 15 elements in 12 groups.
In the description of the benefits of the invention, emphasis is put on the minimisation of chromatic aberrations.
---------- Post added 03-22-2018 at 12:15 PM ----------
The current smc Pentax-DA★ 16-50mm f/2.8 ED AL[IF] SDM includes 15 elements in 12 groups
The two examples of the patent which include 15 elements in 12 groups too (example 4 and example 7) are pretty close to the current DA★.
Example 4:
Example 7:
I therefore think that this patent is that of a revamped DA★ 16-50mm f/2.8, close to the current lens but with some tweaks in its optical formula aimed at mitigating one of the main weaknesses of the current lens, its high level of chromatic aberrations.