var photoindex = 0;
var numphotos;
    
Event.observe(window,'load',function() {
    numphotos = $$('.item').size();
    });

Effect.Transitions.exponential = function(pos) {
  return 1-Math.pow(1-pos,2);
}
function MoveLeft()
{
	if(photoindex != 0 && numphotos > 6) {
	    new Effect.MoveBy('photo_slides', 0, 85, 
							{
							  duration: 0.4,  
							  transition: Effect.Transitions.exponential,
							  queue: 'end'
							});
		photoindex--;
	}
}

function MoveRight()
{
	if((numphotos - photoindex - 6) > 0) {
	    new Effect.MoveBy('photo_slides', 0, -85, 
							{
							  duration: 0.4,  
							  transition: Effect.Transitions.exponential,
							  queue: 'end'
							});
		photoindex++;
	}
}