<div id="trip_mainImg">
<div id="BannerPIC_n" runat="server" class="inside" data-stellar-offset-parent="false"
     data-stellar-horizontal-offset="40" data-stellar-vertical-offset="150" data-stellar-background-ratio="1.25" style="background-position: 50% 60px;background-attachment:fixed; background-image: url(test.jpg);">
</div>
</div>

height = $(window).height();

50% 0px

$(function () {
            $.stellar.positionProperty.limit = {

                setTop: function ($element, newTop, originalTop) {
                    var limit = 300;

                    // Check if we're going over the limit
                    if (newTop - originalTop > limit) {

                        // Call default position property with our limited value
                        $.stellar.positionProperty.position.setTop.call(null, $element, originalTop - limit, originalTop);

                    } else {

                        // Otherwise, delegate to the 'setTop' method of the 'position' adapter
                        $.stellar.positionProperty.position.setTop.apply(null, arguments);

                    }
                },

                // Nothing custom needed here, so we'll just use the built in adapter:
                setLeft: $.stellar.positionProperty.position.setLeft

            }
        });