User Activity

Picture taken with my Canon 70D at around 8:30am. Lens used was my Canon 55-250. Shot taken at 1/500 secs @ f/8 250mm.
Picture taken with my Canon 70D. Shot taken at 1/400 sec., F16, 250mm (lens is a Canon 55-250), ISO at 640.
Maybe it's something I'm doing wrong or a setting I'm not using but I'm having trouble keeping my subject (race bike on a track) staying in focus as I'm holding the shutter down taking a series of pics. Should I be using the h-shutter? I'm using the ...