The camera will auto-expose for the change in light when the PIR is activated - but can take a split second to adjust - so it won't cause any problem to the camera itself, but will affect your recorded image very, very briefly. The only time it might make a difference is if the ambient light has fallen to such a level that your IR lights have kicked in, and the image has gone to black and white, it can again take a couple of seconds to switch back to colour - and then back to black and white when the PIR goes off. I might also say that your camera locations are quite high, and although that might be the 'easiest' place to put them - if you're covering the area immediately in front of your house, you're going to get a lot of tops of heads and few faces. They'd be better off lower down - at about the first notch brick as you go into the rendered front if it was me, and then run the cable up the drainpipe on the right, and up the edge/corner of the house on the left - as I'm more interested in seeing faces than tops of heads.