I am thinking of expanding my photography which is currently action photo-shoots of dogs, to include natural shots of dogs and kids playing and possibly just kids playing. I currently shoot a Canon 70D + Sigma 120-300 f2.8 OS which is fine in bright sunlight using fast shutter, low'ish ISO (200-400) as dogs don’t squint in the sun. If I move to shooting kids I think I will need to move into the shade under the canopy in the local parks to avoid harsh light. I expect to lose a few stops of light so was thinking of getting a Canon 6D which will also shorten the tele effect. I also have a 50mm f1.8 STM which fits full frame. Is this a good idea or is there a better solution in this price range..?