@illininutt wrote:What about cloudy days/overcast days...does anyone still use filters of any kind to make the pictures come out better?
The single most useful filter you can buy is a Circular Polarizer. It can be used on sunny days to make the blue of the sky deeper and white clouds really pop out. It also is very helpful on overcast days, to reduce the reflection of the sky. You might be surprised by how much reflection there is off foliage, for example. Reducing the reflection of the white/gray overcase sky really brings out the color and contrast... of green leaved in Spring and Summer or all the varous reds, oranges and yellows in the Fall.
The image below, for example, was done in the shade with a C-Pol filter to help saturate the colors better...
Heck, a C-Pol can even be useful shooting portraits. If a person has shiny skin, or wears eyeglasses, use one to control the reflections.
A lot of what can be done with a C-Pol filter cannot be replicated in post-processing. That's not the case with most other filters... many can be applied later, with the right software, in your computer. So, shooting digital images you really don't need a lot of filters, not nearly as many as we did in the days of film. But it's still bery worthwhile to get and use a quality C-Pol.
There are times you don't want to use any filter... and a C-Pol "costs" one to two stops (depending upon how it's adjusted), so you don't want to leave on on your lens all the time. A C-Pol works by only allowing aligned light rays to pass through, reducing the "scattered" light rays of reflections. So it works best outdoors when 90 to 180 degrees from the sun. Pointing toward the sun, such as photographing a sunset, the filter will be of little use and is best removed because it actually can increase flare and chromatic aberrations. But selectively using a C-Pol can really help your images.
There are cheaper and there are more expensive, but I mostly use B+W MRC and Kaesemann C-Pols. I've also used Hoya HMC, S-HMC, HD and HD2, Heliopan SH-PMC and a few others. I haven't used, but hear good things about Marumi filters, too.
If you go shopping for a polarizer, you don't want a linear polarizer. Those will mess with your camera's autofocus (and in some cases will skew camera metering systems). You need to be sure what you get is a circular polarizer. That will work fine.
Two other types of filters that can be useful are Neutral Density (ND) and Graduated ND.
The ND fitlers are gray all over and are designed to reduce the light entering the camera. This is done in order to use a long exposure and/or a large aperture in brighter light situations, when you just can't adjust the camera's ISO, aperture and shutter enough to get the exposure you want. People use these for those scenic shots where water is blurred and creamy looking, for example. Or they might be used if you are shooting a portrait and want to strongly blur down the background. For still photography, a 6 to 10 stop ND filter is often in the range needed.
Graduated ND filters are half gray, half clear and are used as described in a previous response. For this type filter, I recommend getting the rectangular type, because you have to be able to adjust the filter up and down to match the horizon in your image. Usually, a 2-stop Grad ND is the most useful, but they come in 1 and 3-stop versions too. I have to say, though, that I have a set of these and haven't found need to use them for several years. I can do as good or even better job in post-processing software... either taking two (or more) shots at different exposures... or processing a raw file a couple different ways... then combining the "correct" part of each image in Photoshop.
Another type of filter that a lot of people use is a "protection" filter. Some use a UV or a Sky filters, others are Clear or simply "Protection". Personally I think it's rather silly to expect a thin piece of glass to provide very much protection to a lens IMO, a properly fitted lens hood does a better job protecting when shooting... and lens caps work really well when storing my lenses. But, do what you want. If a protection filter means you'll get out and shoot more without worrying about your lens, go for it.
Whatever filters you get, it's best if they are good quality glass and multi-coated. Those will have the least detrimental effect on your images and give you the purest effects. Don't cheap out on filters, so few are really needed these days.
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & EXPOSUREMANAGER
