I have booked a hire of the Olympus 300mm f/2.8 this coming week-end to take photographs of wading birds at a London bird sanctuary, along with the EC20 teleconverter. I already have the 50-200mm f/2.8-3.5 and EC14 teleconverter, which combination I used last time that I went in 2014 with some good results, but many small bird shaped specks in large quantities of background. I will be using them with an E-M1 and a good tripod. The bird sanctuary has a number of permanent hides for looking at (and photographing) wild birds, and seems to be a very popular spot with photographers. There are also some areas in which captive water birds are kept, and these are easy to photograph with the 50-200mm without any teleconverter, but I am wanting to take pictures of the wild birds on this occasion. I have not used a lens quite this long before (the longest being the 283mm of the 50-200mm multiplied by the 1.4x teleconverter), and I should be grateful for any tips that people may have for using such a thing effectively. I have found in the past that the small focus points are most useful for rapid focussing with the 50-200mm.