[kh99]

I'm not really a js expert, but this seems to work:

$(document).ready(function() {
    var countdown = 30;
	$('#countdown').html(countdown);
	setInterval(function() {
	    countdown--;
		$('#countdown').html(countdown);
		if (countdown <= 0)
		{
  		    $('.cameraimage').attr('src', $('.cameraimage').attr('src') + '?' + new Date().getTime());
			countdown = 30;
  		    $('#countdown').html(countdown);
        }
	}, 1000);
});

Then you need to insert something like:

<div>Image updates in: <span id="countdown"></span></div>