sorry guys, I made a serious mistake in the calculations in focal length and detent interval. I deleted a few posts that contain incorrect data to avoid confusion.
here are corrected spreadsheets showing relationship between focal length, detent interval and % overlap.
for full frame sensor
for 1.5x cropped sensor
for 1.6x cropped sensor
look for your focal length in the spreadsheet. read horizontally to find the right detent interval with desired overlap. If no suitable detent available, look for other focal length.
Alternatively, find the detent of your choice, choose a range of % overlap, then get the range of suitable focal length.
from the spreadsheet, you can see the max focal length supported by R-D16 is about 300mm (35mm eq) with 18% overlap. the max focal length supported by R-D12 is about 150mm (35mm eq) with 18% overlap.

Please correct me if you spot out any errors.


Note: The coloured bars bracket focal lengths that can be used with a particular detent setting. 60¬?40% means the 60 degree detent interval (6 around), giving 40% overlap for that focal length.
Thanks John for making it clear.