Hi Guys! Need your help... I'm still new to photography, I like landscape shots. My question is regarding ND filters. I have read that its great tool for landscape shot and that it reduces light so you can use longer shutter speed. I try and get one (ND8) but i can't really appreciate the final product. I use it in a bright sunny day. Any particular camera settings that I should try to have a good product? How long is the shutter speed that I need to use?