A polarizer is a must in any photographers bag. No question it can come in handy in many scenarios. Landscapes is known as the number one reason probably, but it can be useful in many other cases. The polarizer reduces glare, saturates, blocks ~2 stops of light, cuts haze, protects, and some are even multi-coated to reduce internal reflections from the digital sensor.
Many may wonder why multi-coated filters are available and what they prevent. Although 35mm film had a gloss to it our nice and shiny new sensors are practically mirrors. When the light comes in through the lens and then hits your sensor with photons they come shinning right back through your lens and to any filter you have on the front. This can set off a chain reaction and create ghosting in your images. Now this isn’t to scare you into buying a multi-coated or even super multi-coated polarizer/filter. These situations arise more often then not when you are photographing a scene with a bright object such as the sun or a metal object.
So would I recommend going multi-coated? Not necessarily. I more then not recommend you purchase a good polarizer. The better quality filters though end up being of the multi-coated kind . By no means does this coating get rid of the ghosting, just lowers it. If reducing flare and ghosting are your prime objectives your best bet is grabbing yourself a prime lens which will have less glass to reflect internally with. I originally started out with the Tiffen polarizers and wasn’t too much of a fan. Do they work? Yes. Work as well as some of the high quality versions? Not in my opinion. When I screw on a high quality polarizer my reflections are no more and too such a dramatic extent. With almost all of photography seeing is believing 
One more thing to look out with polarizers is seeing if you can try the brands. To me they all have different casts, neutrality’s, or saturation’s to them. I don’t mean polarizers with a built in warming filter either. Build quality of the Tiffen put me off, but I found it to be the most neutral in not shifting the image in either direction. I used a multi-coated B+W filter for a while and it had this gray cold cast to it. I constantly fought with the idea it was my photography. Soon after having to get a 67mm polarizer for my other wide angle (damn companies and their filter sizes) I made it a Hoya multi-coated. Soon after I sold my B+W and got myself a 77mm Hoya as well. Hoya’s for me are the best in construction with a smooth twist and bring this fantastic saturation to my images. Not the primary goal, but an excellent addition to my photography kit.
An issue when purchasing a polarizer is do I go for ultra slim or not? The way to answer that is if you already have any sort of regular filter of the same size try it on your lens. Shoot some sample photographs and check for vignetting (darkening around the corners of your image.) Best subject is probably a blue/white sky and your lens set to infinity (manual focus.) If it is something that is a concern then you might seek ultra thin. Ultra thins of course get rid of the thread on the front of the polarizer. Not too big a deal as stacking shouldn’t be going on all that often with a polarizer. At least not for myself. Personally I don’t go ultra. I have to adjust the polarizer without the lens hood first and then reattach it. Plus the extra thread has a bit extra room to grip the polarizer avoiding dreaded smudge marks.
With this in mind I wanted to give a quick example of the difference between a polarized image and a non-polarized image using some waterfall photography. A typical situation where water shimmer, green hues, and rich browns each have a role to play in our scenes.
(non-polarized/polarized)
( (Click the image for a less squeezed version) Take notice of the shimmer on the green leaves on the upper right section of the photograph, the water rushing over the mid-section and upper-section rocks, mid-level rock plateau to the left as well as the saturation of the boulder hugging the far right of the screen.)
Spending some time up at Harriman State Park in the fall helped me get this one. Here you can see the assisting of saturation in the sky and more importantly the ability to see through the water in the foreground. Very important to add dimension to the photograph.
With these items in mind I hope choosing a polarizer becomes more clear and useful. Make sure to always have one stored in a neat pouch ready to go. I currently use the “Tamrac MX-S5363 S.A.S. Compact Filter Case – holds 3 Round or Square Filters up to 77mm” Look for a larger one in case you use more filters.
P.s I wanted to add a note on the program I mentioned in my last post. The major advantage that I forgot to mention (nice job I know) is that by having a program on your PC you don’t have to rely on the Internet for finding fonts on your PC. Not all of use have an air card or when you are out on a special expedition where Internet is just not available.
P.s.s I’m hoping my Nikon D300, Nikon 80-400mm, and my Tamron 17-50mm items come back soon. They are out for regular maintenance and not having your gear really slows you down :-p.
