JQuery :: Can't Select All 'li' Elements Without One Who's Have Class?

There is simple html like this:

<ul id="icons">
<li class="icon1 hoverNow"><img src="some/pic1.jpg"/></li>
<li class="icon2"><img src="some/pic2.jpg"/></li>
<li class="icon3"><img src="some/pic3.jpg"/></li>
<li class="icon4"><img src="some/pic4.jpg"/></li>
</ul>

where class 'hoverNow' means, that opacity of the image is 1.0, while others 0.5. This done with css.
i want to do, that when mouse hover the 'li' element, image, IF it's not in the li element, who's having class 'hoverNow', become with opacity 1.0, and on mouseover, again will have 0.5 opacity. For this, i write this simple code:

[Code]...