Lens filters can block the level of light reaching your camera and protect your precious lens from harm. Taking them up a notch, you can soften faces, make ordinary sunsets breathtaking or add sparkle to a glistening river. In all cases, filters are just what they sound like:
Lens filters can block the level of light reaching your camera and protect your precious lens from harm. Taking them up a notch, you can soften faces, make ordinary sunsets breathtaking or add sparkle to a glistening river.
In all cases, filters are just what they sound like: instruments that restrict certain qualities of light from passing through, effectively filtering out light. It sounds rather mundane, but, when put into good practice, filters can greatly enhance the quality of your video. Let's take a closer look at what makes a good filter.
Glass or Plastic
The quality of the filter is largely dependent upon the quality of the glass (in some cases, plastic) of which the filter is made. Glass is superior to plastic, when it comes to passing light through the filter. Plastic filters tend to obstruct more light from passing through the filter, meaning that you will get fewer of the light qualities you want. The benefit of plastic, however, is that it's less expensive and less likely to break or chip. Depending upon your budget and your shooting environment, less-expensive plastic filters will get the job done. If quality is your main concern, we can't stress enough the importance of choosing glass over plastic.
Today's manufacturing processes have improved greatly, and you'll find that filters are often composites of several materials, the majority of which is glass. Naturally, the glass-is-better rule still applies. Differentiating optics in two similar glass filters from different manufacturers is a difficult task. Most professionals have a trusted brand. Most consumers let their pocketbook choose between the two.
Square or Circular
Filters come in varying forms and sizes. The most notable difference is the choice between square and circular filters. Many professionals prefer square filters, as they can conform to a variety of lens diameter sizes with a matte box. Adding a matte box to your kit is costly, so the circular filter is a good alternative. Circular filters come in a variety of sizes to meet the needs of your specific camcorder. Circular filters have threads, so you can quickly and easily screw them on to the end of the lens. Most circular filters will also allow you to screw additional filters on, although there is usually a limit as to how many filters one can apply before the edges of the filter start to show up in the frame of the video. When you purchase circular filters, keep in mind that you may have to buy new filters if you upgrade to a camcorder with a different lens diameter. In some cases, you can buy a step-down ring that adapts bigger filters to a small camcorder lens. Unfortunately, it doesn't work the other way around. If you buy a camcorder with a bigger lens diameter, the small filter size is useless.
Filters are not just for professional shooters. All shooters should have at least one very important filter in their kit: a UV filter. This filter's primary responsibility is to shield your camcorder's lens from any harm that may come (e.g., scratches, dirty fingers, dust, spit, rocks, etc.). Don't go cheap on a UV filter, specifically for its primary function. This UV filter will go everywhere with your camcorder, and it will most likely be in use in more than 95% of your shots. The UV filter is good for this task because it doesn't affect the light too much. Its added benefit is that it helps to reduce haze caused by UV rays, so images will be much more color-saturated. This is most obvious in sky shots, where the blue values become very rich in color.
Another very useful filter is a polarizer (or "polar" for short). A polarizing filter helps reduce glare from glass and water. It's most convenient to use a circular polarizing filter that allows you to easily spin the filter in a circular fashion until the desired effect is optimal. Circular polarizers are a little more expensive, but they are well worth the price for their convenience and effectiveness.
The last critical filter you may need in your kit is a neutral-density filter (ND, for short). Often, a neutral-density filter is already a part of your camcorder, as it is a built-in feature of many professional and prosumer camcorders. A good ND filter simply cuts the intensity of light reaching the camcorder without changing the color or any other quality of the light. Again, quality is an important aspect when dealing with ND filters. Another aspect of the ND filter is graduation. ND Graduated filters (or ND Grad for short) have the neutral-density effect gradually applied from very little density to full density across the plane of the filter. These are useful in controlling the intensity of light in selective areas of the frame. Common use would be for sunsets and sunrises, where one half of the frame is much brighter than the other half. Graduated filters are not limited to ND filters; you can find them on many other filters, where applying the effect to a certain part of the frame is critical.
Enhancing Your Image
Many more filters exist beyond those few that we've already mentioned. The majority of these filters have limited uses, because of their specific properties. However, they all deal with enhancing certain light qualities to deliver a unique look.
One such filter that is actually quite common is an 812 warm filter. Different manufacturers may have slight variations in the name of this filter, but its main objective is to enhance the warm tones of the image. This filter is ideal for portraits or other shooting environments that might otherwise produce an image that's too cool.
Beyond those that warm up your looks, there are many more filter types that can reduce contrast, selectively limit other color values, create diffusion, make star-points from sources of light and so much more. Experimenting with filters is fun and can be very rewarding. However, we recommend you use some discretion, as any filter you put before your lens will have a lasting and undoable effect on your video.
Alas, Almighty Digital Filters
Many of the specialized filters can be replaced by digital equivalents in post production. Of course, this takes more time, but, if you need a very specific look, it might be possible to achieve it using color correction tools or specific plug-ins. The additional flexibility of the Undo function with digital filters can be a life-saver.
Don't rely solely on digital filters, however. The art of applying optical filters is knowing what you don't want in your image. It's best if you can eliminate the unwanted light qualities with optical filters. If there's unwanted UV haze, it makes perfect sense to use a UV filter. Or take away unwanted glare with a polar. The goal is to filter out the bad with optical filters and then emphasize the good light qualities you captured using digital filters in post production.
When you put your filter kit together, think about the type of shooting environments you'll be in. Ask yourself if there are any specific imaging qualities that you'll want to reduce or even remove. Chances are, there's a filter that will help you achieve that look.
Contributing editor Mark Montgomery is an independent video producer and editor.
Click here to download a PDF Manufacturer's list of Videomaker's Filter Buyer's Guide.