Olympus OMD M10, 40-150 mm 5.6 (not Pro) Daughter took new nervous horse to Dressage. No time to prepare and only 2 mins "in the ring" Obviously No flash! Indoor arena-bad natural light through dirty skylights. I set WB at cloudy, cranked the ISO up to 400 and had the lens wide open. Result with a moving (trotting, not full gallop!) horse were blurred images -a mix of low shutter speed and probably my movement despite image stabilisation. Colours were remarkably accurate. With my hindsight I think I should have cranked the ISO much further -it seems to go up to about 20,000! Then I wondered if I could have set the shutter speed to say 125 and cranked up the image in Lightroom. (It was set to Aperture priority wide open as I just wanted "light") What should I have done?