Buried deep within my closet is my collection of screw-on filters. I have warming and cooling filters for adjusting white balance, I have a red filter that can be used to increase the contrast in a black and white image, I have a yellow filter for darkening a black and white sky, I have special effects filters that soften images, add starbursts and do other cool things that were actually popular back in the 80s. I haven't dragged that box out in years and haven't really had a need to, either. Why not?
Because most of those old filters are obsolete. When film ruled, filters served a very important purpose. We didn’t have computers or post processing back then, so if we wanted to adjust white balance without changing film, we could just screw on a filter. If we wanted to add a special effect, we could screw on a filter. If we wanted subtle changes in our black and white photos, we could—yep, you guessed it—screw on a filter.
Today, we can do all of those things in post-processing, and the beauty of waiting until after we’ve shot the image to make those changes is that we can easily back out of them if we change our minds. When it was done on film, you were pretty much stuck with whatever you ended up with.
But I didn’t tell you all that just so that I could arrive at the conclusion that you don’t need to have any filters, which is probably what you’re thinking right now. Certain filters still serve very important purposes, so my intention is to make sure you understand which ones you need and which ones can just stay in that box in your closet.
This is probably the most important filter you’ll own. Also called a “haze” or simply a “clear” filter, these were originally intended to remove the blue cast from photos shot on sunny days. Today this is actually an obsolete reason for using one of these filters—film cameras were very sensitive to UV light, but digital sensors are much less so. So you don’t really need a UV filter to block UV light. You do still need one, though (depending on who you ask).
UV filters are essentially clear, so they don’t have an impact on the amount of light that reaches your sensor. What they do actually do is protect your expensive lens from dust and scratches, and you really can’t put a price on that.
That reason alone is enough for me to recommend getting a good UV filter, but there’s the catch—it has to be a good UV filter. Cheaper UV filters may actually have a negative impact on image quality, so don’t sort by price if you decide to buy one of these on Amazon.com. You need a good quality version if you intend to leave it on your lens all the time.
UV filters can also help lessen chromatic aberration, or “purple fringing,” which is what can sometimes happen in areas of high contrast, especially in inexpensive lenses.
The effect of a polarizing filter cannot be simulated in post processing, which makes this an almost indispensible tool for anyone who takes a lot of photographs outdoors. Polarizing filters do exactly what the name implies—they filter out polarized light, which does a couple of things: first, it dramatically reduces reflections in glass or on the surface of water. Have you ever tried to shoot something at the bottom of a clear body of water, but discovered that all you got was the reflection on the surface? You can eliminate this problem with a polarizing filter. You can also use a polarizing filter to darken the sky, enhance or saturate colors and to improve the contrast in a scene.
It does require a little bit of practice to get the most out of a polarizing filter—they’re circular, which means that you can rotate them as needed to get the best effect. You’ll get the most impact from your filter if you keep the sun at about 90 degrees to your position (to your side rather than in front of you or behind you). Rotate the filter until you see the sky darken or the reflections disappear, depending on what you’re going for.
Remember too that you’ll cut back on some light when you use a polarizing filter, so they’re not good for low light situations.
Neutral density (ND) filters
You know those misty waterfall images that you’ve always been so impressed by? Most of these are shot with the help of a neutral density filter.
Neutral density filters have one very important job: they cut down on the amount of light that reaches your sensor. That in turn allows you to shoot images in the middle of the day using slow shutter speeds that wouldn’t be possible without the addition of that filter. Those misty waterfalls? You need a slow shutter speed to make the water look like that. And if it’s a bright day, you can only do that with a neutral density filter.
Neutral density filters aren’t just good for shooting waterfalls, you can also use them to get motion trails during the day, or to even completely blur moving objects out of existence. Have you ever wanted to shoot a monument without any tourists? Without an ND filter, your only real option is to visit in the middle of the night when the tourists are all asleep in their hotel beds. But with a very dark ND filter you can use a long shutter speed to shoot the monument, and all but the most lingery tourists won’t even register in the image.
Neutral density filters are rated according to the amount of light they block—a 1 stop filter blocks 1 stop of light, a 3 stop filter blocks three stops of light and so on. You can buy ND filters in sets or you can get a single variable ND filter, which lets you adjust the number of stops of light reduction.
You can also purchase graduated neutral density filters, which have a tinted half and an untinted half. If you’ve ever been disappointed by landscape images you shot during the day, you should consider adding a graduated neutral density filter to your camera bag. To use one, you simply place the darker half over the sky and the lighter half over the ground, and you’ll get an image with more color and clarity in the sky. This can make a big difference in scenes that have a lot of dynamic range. Graduated NDs are available with different edges—a filter with hard edges has a more rapid transition from dark to light than a filter with soft edges does. And you can also get “reverse” graduated neutral density filters, which transition from dark gray to a lighter gray rather than from dark to clear.
If you love macro photography but have yet to spring for a macro lens, consider buying a set of close-up filters. Now, I’ll be the first to say that a close up filter is not as easy to work with as a macro lens, nor does it create images that are quite the same quality. But in a pinch, it takes some pretty decent photos of really tiny things. Close up filters come in different strengths—the one you choose depends on how close you want to get to your subject. One drawback to close up filters is that they don’t give you a lot of depth of field, so if your goal is to get good clarity from foreground to background, you’re going to be disappointed. But if you’re willing to consider some artsy, shallow depth-of-field macro shots, these filters will be a great investment.
These really aren’t filters in the traditional sense of the word—bokeh filters are made from black plastic, and they have a shape cut into the center of them. The end result of using one of these filters is an image that contains shaped bokeh.
These filters are fun and really inexpensive, but you don’t need to limit yourself to just what’s commercially available. You can make shaped bokeh filters yourself out of heavy black paper, too—just cut a piece the shape of your lens barrel, fold it in half, and cut the shape out of the center using a pair of fine scissors. Unfold the paper and place it over the front of your lens when shooting.
Post-processing has eliminated the need for a lot of photographic filters, but not all of them. These tools are by no means required purchases, but compared to some other equipment you might buy for your hobby they’re small investments that can produce big benefits.
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