Just received the new 2X Tele Converter DMW-STC20 for the Panasonic Lumix S PRO Leica 70-200 F4 O.I.S. Sample image below from my SL taken at 40m
Panasonic 2x converter ( 400 mm - Leica - Spot - Aperture priority - ISO 1600 - ¹⁄₅₀₀ sec at ƒ - 8.0 - 0 EV - ) -1230695.jpg
Very happy the results so far although maximum aperture is down at f/8.0 - OK for sunny days. Total cost for both items less than 50% of the Leica 90-280 f/2.8-f/4.
The DMW-STC20 with the Leica 280mm might be fun!