I don't think there's a smilie for anything that wicked, Garry....
Or alternatively there's the one I suggested by Lee - I haven't read it but it's got some good names behind it...
http://www.leefilters/camera/products/range/ref:I46CC007258785/
Sorry, the link doesn't work for some reason. Go to www.leefilters.com and you'll find it under publications.
thanks , looks a good book , do you think its "lee" specific though ?
I'm also drawn to this http://www.amazon.co.uk/Digital-Photographers-Guide-Filters/dp/0715326694/ref=sr_1_1?ie=UTF8&s=books&qid=1238430446&sr=1-1
its got 4 good reviews , any one read it ?
thanks