Question: What does a polarizer do that PP cannot?

[cutsman]

So I've seen a number of photos on flickr and other sites taken using a circular polarizer and the results were pretty impressive, nice contrast, saturation, and clarity.. especially in the skies. Now this might be a dumb question with an obvious answer, but can't I obtain similar effects through post-processing without having to spend the money for a polarizer and without the loss of light?

Thanks!

 

[Scarlet Fever]

Not really. The polarisers can change the amount of light being reflected off something. To try to replicate that in PP would be near on impossible.

There is a reason so many people spend the money buying polarising filters. If they could just do it in PP, they probably would.

 

[maxi]

I guess I just come from a different age in photography, but I just want to be able to get as much done in the camera as possible.

A circular polarizer affects your exposure in ways PP probably can't emulate (or it's just too time consuming). Using a polarizer is trivial (Just rotate until you like the effect) and really beneficial for daylight shooting.

 

[OreoCookie]

No, there is no way. There are many materials that reflect light depending on the polarization, you can't possibly emulate that.

 

[Westside guy]

Here's a good real-world example of what a polarizer can do that can't really be emulated in post processing.

Let's say you're standing by a lake, shooting a picture of the water near your feet. The sun is shining, so all you're getting is the glare of the sun off the surface of the water. Now if you pop your circular polarizer on your lens and rotate it, you can suddenly see all the fish that are in the water. (If you don't believe this, get some polarizing sunglasses and go down to a lake on a sunny day)

Now, admittedly, in post-processing you could cut down the sun's glare with curves or highlight reduction; and then you could paint in some fish.

 

[scubaj]

Good analogies here...and explanations. A polarizer reflects light differently, and while you can produce the color variations through post processing, some of the effects can't be duplicated in PP. Having said that, there is much that can be done in Photoshop, but why spend hours on an image trying to replicate something that a one time investment of $50-$150 would have addressed for a lifetime of imagery?

 

[Westside guy]

Technically what a polarizer does is remove those light waves (okay, photons are particles, but anyway) that are oriented in one particular direction.

Edit: Er, or is it that it only lets those through? Anyway it selectively blocks some of the light.

 

[Cave Man]

Almost all my film filters are collecting dust. The only filters I have now are:

1. Circular polarizer
2. Neutral density
3. Gradient neutral density

These are the only ones that cannot be replicated in post processing (except with sequential exposures followed by HDR for 2 and 3).