// Create an array of images that you'd like to use
            var images = [];
            // The index variable will keep track of which image is currently showing
            var index = 0;

            for(k = 0; k < $("#background_img img").length; k++) {
                images.push($("#background_img img").eq(k).attr("src"));
            }

            // Call backstretch for the first time,
            // In this case, I'm settings speed of 1500ms for a fadeIn effect between images.
            $.backstretch(images[index]);

            // Set an interval that increments the index and sets the new image
            // Note: The fadeIn speed set above will be inherited
			if(images.length > 1){
				setInterval(function() {
					index = (index >= images.length - 1) ? 0 : index + 1;
					$.backstretch(images[index], {speed: 2000});
				}, 5000);
			}