Upload & Sell: On
Yes, f/11 very dark
I have Infrequently used my 2X Apo extender with my f6.8 560 Telyt lens which yields an f13.6. Fairly dark and quite long and must be used carefully. Not optimum certainly for fast moving subjects. Also, not quite what you asked. Image was acceptably sharp, but the Tug Boat in the image below was moving, there was wind and I had to push down on the whole assembly to try to keep things as vibration free as possible. The tug boat and the lighthouse were out a fair distance in Long Island Sound. Image has been printed to at least 16" X 24" Fuji Crystal Archive print.
"Lighthouse Point" Photo of the Southwest Light, New Haven, CT as the Morgan Reinauer (large, high powered tug) passed by in spring of 1999; taken from Lighthouse Point in New Haven. The tug's tow lines are taught as it pulled a large barge. Image taken with Leica R8 and Leica f6.8 560mm Telyt lens and Leica 2X Apo Extender (effective 1120mm or 22X what see by eye) on Fujichrome Provia 100 film.