I have been trying to get shots of clouds and holding an extremely long exposure to get a cool effect. But everytime I take a shot it looks horrible. I have been trying to do it at sunset where the sky is very red. When i take the shot with the long exposure all that turns out is a extremely bright picture. But by the time I wait till it is darker, the redness of the sky is gone. I am using a Nikon d-40

Please help


Heres an example of the redness being lost.