4 ACCEPTED SOLUTIONS
Polarizing filters do increase color saturation. You should be able to see it in your view finder and LCD display.
A good way to visualize how this works is to aim your pointer finger at the sun while holding your thumb straight up. Everywhere your thumb points when you rotate your hand (while still pointing it at the sun) is where the polarizer will have the strongest effect. They require the camera to be pointed at a right angle to the sun for maximal effect.
The problem is all color saturation is not equal. It can vary and not be uniform across the frame. Another is when used on a wide angle or UWA lens the effect can be less. Which can make it quite difficult to see the effect in a viewfinder or LCD screen. Cheap ones can degrade IQ.
If I missed anything maybe Tim can help me out. This is right up his alley. 
@iris wrote:Remarkable results with your HDR....I am interested in HDR but have no real understanding of it. I get the impression you dont need a lot of lenses? ? what? I saw friends on a recent trip to the mountains raving about the little bit of weight they took with their cameras...I'm not sure I understand HDR at all right now?
You need a tripod, not a lens. Well, obviously a lens, but a tripod is the standout requirement for HDR. Basically all you're doing is taking photos as multiple exposures (very dark, dark, normal, light, very light) and combining them into one image with a large (or "High") dynamic range (the 'distance' between the darkest and lightest points in an image); hence the name HDR. You can shoot it without a tripod, most software can try to align the frames, but it's much better to just use a tripod if available.
As mentioned above, Photomatix is the name brand in HDR, but that's changing and the technique evolves. It's far superior to control in Photoshop, however. There's a plug in for Lightroom called Enfuse (free) that is very powerful, but not as user friendly. And the soon to be released Lightroom 6 will have HDR built in; we're all eager to see what that looks like.
The examples that eBiggs posts really show tone mapping more than HDR. All HDR (and non-HDR) images have to be tone mapped to display on a LED screen, but if you search for "tone mapped" you'll see that there is a look associated with the term.
On the flip side, HDR images can be tone mapped to look normal, mearly trying to squeeze a large dynamic range into one picture. A very common use is in Real Estate/Architectural photography when dealing with lots of windows. The difference in light levels between the inside lights and outside can often be far too large for a camera (even though your eyes can adjust ok). So you're left with either completely white windows, or dark interior. The goal isn't to make something that looks 'tone mapped', but to have it look normal. Like this:
Even with lighting I couldn't completely balance out the sun, so I simply stack a few images to fill in the low spots. It doesn't look like anything special, but it's not supposed to. You can see the outside has a slight bluish tint to it. Poor tone mapping on my part.
Another example, where the left and back walls were windows, creating a bright gradient out of the lower left, leaving the back completely dark.
Again, you're not suppose to look at it and think HDR, it's suppose to look like an ordinary photo. Just some examples of another side of HDR...
Polarizing filters do increase color saturation. You should be able to see it in your view finder and LCD display.
A good way to visualize how this works is to aim your pointer finger at the sun while holding your thumb straight up. Everywhere your thumb points when you rotate your hand (while still pointing it at the sun) is where the polarizer will have the strongest effect. They require the camera to be pointed at a right angle to the sun for maximal effect.
The problem is all color saturation is not equal. It can vary and not be uniform across the frame. Another is when used on a wide angle or UWA lens the effect can be less. Which can make it quite difficult to see the effect in a viewfinder or LCD screen. Cheap ones can degrade IQ.
If I missed anything maybe Tim can help me out. This is right up his alley.
iris,
I have that very Siggy. It is a great lens for the money and will give all but the many thousand dollar rigs a run.
I use a B+W polarizing filter but I use it on more normal lenses. One problem with the big Siggy and its ilk, is they are slow. It really can't afford any f-stop penality. And filters of any kind degrade IQ.
Now what do I do about it? Photoshop of course. In reality, the only filter that you can't duplicate in PS is the ploarizer.. But you can agive it a darn good try.
BTW, have you done any HDR? I have beeb toying around with it a little bit. Some pretty "interesting" results!
