The yellow/orange is probably my favourite for landscapes when I want to darken the sky and enhance cloud/sky contrast or cut through blue haze on distant subjects.
However I would be wary of using it without due thought in other scenarios - for one, because it costs you two stops of exposure. It is most useful when you want to darken blue and, to a lesser extent, green in relation to other colours. Whether this will improve contrast depends on the colours in your photo. For example, if your subject is wearing blue jeans and a black shirt, using an orange filter would reduce contrast by darkening the jeans, which otherwise would contrast with the black shirt. Whether that is desirable depends on your intent.
Last edited by andrew.roos; 06-17-2013 at 02:55 PM. Click to view previous post history.