Thank you very much. Those are all very useful comments as I learn more about this little lens.
I have attached another recent photo taken with this lens, also at F/2.8. I took this photo because there had been a storm with strong winds which brought down most of the leaves and some trees. This fellow fell on poor old mile post 19. The upper part of this image, of the tree branches against a cloudy but bright sky, shows some of the nervous bokeh about which I spoke.
My take away, is that if I am careful, F/2.8 works quite well. Sharpness is pretty good but I will try to avoid too much high contrast.
Lowell