I get a few comments from time to time regarding my waterfall shots, particularly about the saturation level and how much I have bashed it over the head in photoshop ;) I had another great example from a few years back, however I was at a scene recently where the effect of the polariser was very pronounced and thought its a great example why every photographer should have this filter in their bag. There simply is no photoshop means to replicate it.
The attached images were shot at the same time (well one after the other ;) ) and processed identically, ie I edited one (the non-polarised one) and simply copied the edit settings across to the polarised image.
As one can see the difference is very marked, the polariser has simply removed reflected oblique light in the scene which in reality results in the actual colour of the element being seen – there is plenty of Greek writing about how this works and there are volumes on this, a great cure of insomnia in my opinion. For me this is the biggest contributor for waterfall shots, it can at anytime of the day (at the right angle) turn a flat nasty scene into something half decent.
In this case, very little PS bashing was used ;)