I just wanted to say thanks for all your advice. Rather than spending going on for £100 straight away for my main lens, I got thought I'd buy a filter for my kit lens (46mm). As the lens is small, the filter was a lot cheaper to dip my feet in water with. Anyway, it arrived this afternoon and I nipped out for a couple of test shots. Please ignore the focus and lighting for now. With the water, I am well impressed. I'm now off to buy another filter for another lens.