Another thing that looks odd to me is the camera angle -- it looks like you're using a "wide angle lens" -- 35mm or so, or maybe even wider. That makes the lighthouse look bent; we're seeing way too much of the underside of the widow's walk to look like a natural view. I'd consider changing the camera to normal (in RDS the 50mm setting is "normal," as it is in 35mm photography). You'll have to back the camera away from the lighthouse to get a similar (but flatter) composition. I think this will help volumes. It's a really cool pic, BTW. I've been commissioned to do a pen-and-ink of a lighthouse and was working on it last night when the earthquake hit here in SF. A little frightening, but I'll never forget the lighthouse. (It was my first earthquake, and a small one at that, but now my drawing of the lightouse will forever be intwined with that earthquake.)