Why use filters?

Filters come in handy for multiple reasons, effects and image enhancements primarily. I can post a bunch of examples but there are many places on the web that already do so. B&H Photo Video has some good examples of what various filters are capable of doing. Digital Photography School is another place to get more information about using filters. In the film days, there were contrast filters for black and white film. Yellow, the least, orange next, and red the most. But image editors can make most of those adjustments, eliminating the need for those filters. Many people use UV, Skylight, or clear filters to protect the front element of the lens. There are also people who would NEVER use a filter to protect the lens. They say the extra glass can affect the image. I myself use filters to protect the lens and I've not noticed any noticeable difference. I'd rather replace a filter than pay to have a scratched front element replaced! Some filters will come in handy, others are simply for extra effects. Here are some of the most commonly used filters.

Polarizers are used to reduce and/or eliminate reflections, like when taking pictures of water, store fronts (glass), or any subject that has a lot of reflected glare. The front ring turns freely so you can adjust the 'alignment' of the filter for the effect you desire. Have you noticed how you can see fish or the bottom of a stream when you wear polarized sunglasses? Tilt your head left or right and see the change in effect the glasses make. A polarizer does the same thing for your camera. They work best when the light is at a certain angle to the lens. There will be instances when they seem to have little or no effect. This is due to the angle of the light source illuminating the scene. Polerizers will require an exposure compensation because they do reduce the amount of light entering the lens.

Neutral Density (ND) filters are used to reduce the amount of light entering the lens. They are usually available in a couple of densities, like 1stop, 2stops, 4stops, and can be used in any combination, providing you don't get any vignetting (shadows in the corners of your images) with that particular lens. (For example: ND 0.3 is 1 stop, ND 0.6 is 2 stops, ND 3.0 is 10 stops, etc.) These come in handy when you want to use a slow(er) shutter speed to blur waterfalls and streams for silky water for example. If the scene is bright, you won't be able to use a slow shutter speed because the lens can't go small enough to get the proper exposure. ND filters can also be used to allow use of a wider aperture in order to control the depth of field more. Good for portraits and wildlife shots to blur the background. This is where the ND filters come into play. They are like sunglasses for your camera, WITHOUT the polarization. Variable ND filters are basically two connected polarizers, where one element rotates and one stays fixed. Some people like them, but I myself wouldn't care to use them.

Graduated Neutral Density (GND) filters are neutral density filters that cover only a portion of the lens, usually half. These are used in instances when half of the scene is very bright and the other half is not. Like when the scene has a bright sky and a dark foreground. The dark ND area is placed over the brighter area of the scene to reduce the light intensity of that part of the scene, like the sky. The graduated part is that they change from no ND to ND gradually so there is not a hard line separating the two areas of the image.

Star (Cross star) filters create a "star" effect for pinpoint light sources, like street lights, candles, etc. They usually come in 2x, 4x, 6x, and 8x (2, 4, 6, or 8 stars). It's a neat effect. Sometimes they are called star burst filters. They work nicely on glary rippled water also, but could be a little intense, depending on how much the water is ripply. They even make streak filters. They're like a two point ray as opposed to a "cross star" which would be a four point ray (a star).

Investigate what various filters can do for your images and get a few to experiment and enhance your images. But REMEMBER - adding filters on top of filters to your lens may cause vignetting because they extend into the field of view of the lens. Most people will remove any existing filters and only use the filter that is required in order to eliminate this. Some people will buy only the most expensive filters, but don't get the cheapest dollar-two-ninety-eight ones! I like Hoya, Tiffen, and Cokin brands. B&W filters are top quality and their price reflects that.



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All images © Bill Harbison - All rights reserved