$(function() {
// OPACITY OF BUTTON SET TO 50%
$(".latest_img").css("opacity","0.5");

// ON MOUSE OVER
$(".latest_img").hover(function () { 

// SET OPACITY TO 100%
$(this).stop().animate({
opacity: 1.0
}, "normal");
}, 

// ON MOUSE OUT
function () { 

// SET OPACITY BACK TO 50%
$(this).stop().animate({
opacity: 0.2
}, "normal");
});
});