The Helios 10x42 AQUILA HR Waterproof Porro Prism Binoculars have a close focus range of about 5 metres and although not quite as close as the 8.5x42's, the 10x magnification more than compensates. The 10x42 AQUILA binoculars boast a 6.0° field of view makes the tracking of birds on the wing easy, even for this powerful magnification.