Long ago, before Photo Editing and Computers a great innovation came along called Panchromatic Film. Panchromatic film rendered the image more like the eye sees things, only in Black and White of course. Today most BW films on the market today are Panchromatic and as most of us now it is very sensitive to Blue light and less sensitive to Red and Green. This is why when you take an unfiltered photo of a blue sky it comes out white. When printing on regular paper any difference between the clouds and sky is normally lost. With scanning of negatives you can regain some of that detail, but for really dramatic skies the use of a filter can make a landscape really dramatic.
When using filters you have to have an idea of what is going to happen to your image for predictable results. Exposure is a little trickier too because you have to factor in that the use of a filter changes the amount of exposure time or aperture required to make the exposure. Before modern in camera light meters become the norm you had to calculate this by “the filter factor”. There is a ton of technical information involved and that’s really outside the scope of this article, so I won’t go into it. The information is widely available on line. Wiki has a good chart that converts your filter factor to Stops.
http://en.wikipedia.org/wiki/Filter_factor
For a better demonstration of the use of filters and their effects on colors check out Trash-Stars photo on flickr.
http://www.flickr.com/photos/livingbraindonor/4237077008/
Like anything over using filters for special effects can be overdone, but used for a desired effect it can bring a new dimension to your work. Ansel Adams was a master at filters and was open about using them to achieve his vision of an image even if that image didn’t exactly give a true representation of what you might have seen had you been standing next to him when the photo was shot.
Thanks to digital photo editing and the decline of true Black and White film photography filters, especially in common sizes have gotten really inexpensive. If you’ve only used the yellow filter that came with your old Pentax k1000 you bought off eBay you should be able to have a lot of fun learning to master a new tool for your kit. Filters aren’t just for landscape photography, either. Filters can enhance or change someone’s appearance, diminish skin flaws and bring life to a portrait.











