During my last stay in the spring I walked along the opposite side and found that the waterfall is too far away to get good pictures of it when you are below the Mill. I found a very convenient small layby near the waterfall and was able to take some nice shots with various ND filters creating long exposures. The last photo is taken a little further up the river looking towards the castle. Both photo spots are marked on the aerial view taken from a very informative book about the Castle which Rob provides in Curlew cottage.