FANCY FILTERS

Take a closer look at car commercials nowadays. Most will show a shiny automobile speeding down a dusty road with clear sky and buttes in the background. Take another look at that sky. In almost every ad they do the same thing: throw in a graduated filter that darkens or colors the sky while leaving the bottom half of the picture normal. If you look closely you may even see that the tops of the mountains are also darkened by the filter. The effect is pretty and also performs an important technical function: in the real world the sky is usually much brighter than the ground. Cameras with automatic exposure will split the difference between the sky that's too bright and the ground that's too dark leaving your car and roadway in murky shadows. The solution is to open the lens iris and overexpose the sky. Now the car and foreground look great but the light blue sky has turned to chalky white. Enter the graduated filter, a piece of glass that is colored at the top and clear at the bottom. By positioning the camera and glass correctly, the sky will be darkened by the filter while hubcaps and road dust still glisten in the sun. A neutral gray graduated filter will simply darken the sky while a blue filter will artificially make the sky blue. It's popular nowadays, especially in desert shots, to use a reddish or coral graduated filter making the scene look like it was shot at sunrise or sunset or in the searing heat or in the glow of a nuclear bomb blast. This is just one example of how a filter can solve a technical problem while adding some flavor to a scene.

Must-have filters

If you have no filters, other than the color temperature correction filters built into your camera, ask yourself: Am I an ENG-type person that shoots and runs, using a filter occasionally just to solve problems, or am I the kind of person who paints each image like an artist playing with the colors and highlights until they are perfecto? If you are the first type of person, you'll probably need the following:

1. UV (ultraviolet) or skylight filter - These two slightly pink filters are similar enough to be considered interchangeable, so you only need one or the other. Both make hardly any difference at all in your picture although they slightly reduce blue atmospheric haze in seaside shots and in long panoramic shots at high altitudes. Their main job is to protect your expensive coated lens from water spray, sand, fingerprints, dust, and nearby sneezes. Ocean air is filled with salty sprays. The geysers at Yellowstone emit a mist of mineralized water; the silicates in the water stick to the glass in your lens like glue when the spray evaporates. When the skylight filter gets smudged or fogged, just remove and wash it, something you
   cannot do with a $2000 camera lens. And if the skylight filter gets scratched, pitted, or hopelessly dirty, just throw it away and install a new one. They are not expensive. If the perfectionists among you are still debating over the choice between skylight and UV filter, here's the difference: The UV filter is just a tad pinker, removing more of the ultraviolet light than the skylight filter.
   
   
2. Polarizing filter - This filter reduces shine and glare. It can darken a sky while leaving the clouds just as white as before (unlike a graduated filter) thus exaggerating the brightness of the clouds. Polarizing filters reduce the shine in water making it easier to see through the water revealing fish, fauna, and deep blue colors below the surface. Polarizing filters erase the shine from windows making you better able to see through the glass. Polarizing filters change the white shine of hot pavement back to the original black tar. In car commercials polarizing filters reduce the glare from chrome and shiny paint, accentuating the deeper colors.
   
   Remember that a polarizing filter, in order to work correctly, must be rotated to a certain position. Make this adjustment before you start the shoot. You may find it handy to place a mark, perhaps with White-Out, at the top of the lens filter when it is in the most effective orientation. Once you have found this "best" position for
   the filter, you will find that most other shooting circumstances will call for the same orientation. With a highly visible mark at the top of the filter, you can position the filter at a glance rather than experimenting with it for each shot.
   
   Remember that some lenses rotate as you focus, and the filter, if screwed onto the outside of your lens, may rotate with the lens, changing its orientation. By not screwing the filter on tightly, you can hold it between your thumb and forefinger, holding it steady while the camera lens rotates. Some polarizing filters rotate separately from their screw threads allowing them to move freely even though the mechanism has been threaded tightly onto your lens. There is another
   solution to this rotating lens dilemma that I'll get to shortly.
   
   
3. Neutral density graduated filter - As mentioned earlier, TV cameras don't like high contrast ratios. Bright things and dark things cannot both look good in the same picture. One solution is to aim some extra light at the darker parts of your picture, a process that requires extra lights or reflectors. A second solution is to use a graduated filter so that the bright part of the picture gets dimmed by the dark part of the filter. The neutral density graduated filter is usually used to darken a bright sky, but it can be rotated 90° and used to darken a brighly lit street on the left side of the picture while someone is lurking around a shadowy corner in the right side of the picture.
   
   
4. FLD fluorescent filter - Professional cameras are equipped with built-in filters, selectable with a thumbwheel or switch. The simplest models have simply INDOOR and OUTDOOR positions, while better models have various color temperature settings, including fluorescent color temperature. If your camera doesn't have this setting, you'll rue the green tinge fluorescent lights impart to your shots. Solution: Slap a slightly pink FLD fluorescent filter onto the lens to banish the green ghoulies.
   
   
5. Blue 80A or 80B filter - Same situation as above, if your camera lacks the built-in filters to maintain proper colors when shooting indoors with common incandescent lights, slap on the blue filter to get the red out.
   
   The above filters cost about $20 - $50 apiece and can screw onto your lens where the lens hood used to be. You then screw the lens hood onto the filter. Naturally, the filter has to be the right size in order to fit your camera lens. Camera lenses are measured by their diameter in millimeters, so if you know your camera's lens size you will be able to locate a filter. Examine your lens, especially around its outside rim to see if the diameter is printed there, usually a two digit number followed by mm (millimeters). Most lenses range from 43 to 77 mm. Don't confuse the lens diameter with the lens focal length, also measured in millimeters. If in doubt, you could always take your lens to a camera store to see what fits. If you cannot find exactly the right filter, but something close, or if you already have filters from a previous camera, you can buy a stepping ring which will have
   one set of threads to fit your camera lens and another set of threads to fit your filter marrying the two.
   
   Fancier filters
   
   The second category of videographer is the artist, one who would stock a number of specialized filters. You could buy the glass filters separately, each mounted in its own threaded ring, but that becomes expensive. The solution here is to buy a filter holder oe matte box that attaches to the outside of your camera lens. The
   holder has slots allowing you to drop unmounted glass filter squares into the holder. The holder accommodates several squares at once so they may be teamed up for a cumulative effect. The unmounted squares are cheaper than the round, mounted lenses, but their big advantage is that they don't rotate with the lens. The holder stays in the same position while the camera lens rotates, allowing polarizers to remain properly aligned, and graduated filters to keep their orientation. You may ask yourself why bother with fancy filters if you can just run your video signal through a special effects device and add color or whatnot to the image in post. That's a fine idea if you have lots of time and really know your colorizers and paint programs well. Personally, I'd rather slap a piece of glass in front of the lens and know exactly what I'm getting instantly. You can make a star twinkle without rendering a single frame, or add color in a perfectly smooth
   graduation (as opposed to those steppy backgrounds you get with low cost digital effects gadgets). And just try to make a keyhole or binoculars vignette on your Toaster; it can be done, but not in the nine seconds that it takes to drop a filter or cutout in front of the lens. Just think of the copying and pasting you'll be doing with your computer in order to create multiple images, especially if they rotate
   around the central image. Filters are great because they are simple and fast.

Sales pitch over, here are some of the fancier filters that may find their way into your camera bag.

'Twas a dark and foggy night

Fog filters soften sharpness and moderately lower contrast while causing bright parts of the picture to glow as if surrounded by a vaporous mist, cloud, or smoke. While David Speilberg makes mist the hard way by blowing fake smoke onto the set and shining lights through it (he loves this shot, you find it in nearly every one of his movies), it's easier (albeit less dramatic) to slap a fog filter onto your lens and dress your actors in damp slickers. Light streaming through windows or emanating from headlights exaggerate the fog effect with a visible flare. Normally lit scenes with subdued highlights will show very little effect. Double fog filters approach the consistency of wax paper and achieve pea soup fog. For this effect to look most natural, employ overcast gray lighting.

In a pinch, you can make your own fog filter by spritzing dulling spray or a soap solution onto your skylight filter. Bug spray or deodorant spray will also work. Although these quick and dirty methods will fog your lens, they tend to reduce picture sharpness, something the professional fog filters avoid to a large degree. Low contrast filters, like fog filters, also reduce contrast (hence the name) but maintain a sharper image than their foggy
brothers. Low contrast filters lighten shadows, leaving the bright parts of the picture untouched (no glowing halos). Unlike fog filters where you want the effect to show and therefore light the scene to emphasize the effect, low contrast filters are subtle. They may bring excessive contrast in a picture down to where your camera can easily digest it. In normal scenes, a low contrast filter may created a smoky look to a room making the image less stark and more dreamy. Soft contrast filters work the opposite of low contrast filters; they darken the highlights while perserving the darkness of shadows. Like their low contrast brothers, soft contrast filters also produce more usable contrast range for your camera.

Diffusion filters reduce image sharpness without making the image appear fuzzy. They are great for removing distracting details such as wrinkles in facial close-ups. Denser grades of diffusion filters create soft dream-like scenes.

You can make your own diffusion filter by stretching a nylon stocking or a fine silk mesh over your lens. If the mesh is white, it will also lighten shadows. If the mesh is dark, it will reduce highlights. The finer the mesh, the less obtrusive the effect. The mesh should always be held close to the lens; the farther it is away, the more it intrudes into your picture. Keep your lens iris medium to wide open to minimize the chance that the lens can focus on the strands in the mesh.

A mesh works by defracting light, bending it out of the image plane. Tiny details like wrinkles are like single bullets being deflected by the winds; they don't hit their target and disappear. Larger objects, such as eyes and other facial features, are like an army of guns firing bullets at the target. Even though some bullets may drift, 99% hit the target and stay visible. Thus, net-type filters erase blemishes without making the rest of your image fuzzy. Nets can come in various colors to warm up shadows (red nets) or enhance flesh tones (skin tone nets). Then there are hair nets to keep your fleece out of your food, and fish nets to trap tuna. Keep this up and a net will be waiting for me somewhere.

Star filters make points of light look like stars. Their effect is hardly noticeable in normally lit scenes. Dark shots with bright lights in them, especially sharp points of light, will display a number of spokes coming from the light. This filter is manufactured by finely etching lines in the glass to defract the light to form the stars. If parallel grooves are etched in one direction, you would get a two-point star which looks like a streak, great for enhancing the appearance of movement. Etching lines in several directions create more points to the stars, allowing 4, 6, 8, and 12 point varieties. When the lines are etched closer together, the stars appear fatter, appropriate for accentuating the flair flamboyant stage lighting.
Wider spacing produces finer more delicate stars.

In a pinch, you can make your own star filter by wiping a fine film of oil (perhaps from touching your nose with your finger) back and forth across the skylight filter. Make parallel lines with your finger. Then wipe your finger across the lens perpendicular to the first set of lines. This should make a 4-pointed star. You could then draw an X adding two more points to the star. Be very sparing with the oil; the effect is quite pronounced.

A center spot filter will create an image that is sharp in the center and something else around the periphery. A center spot with fog, will create a dreamy halo around someone's face. The outside of the picture could be fuzzy, diffused, out-of-focused, or colored depending on the filter. Wedding videographers use these filters when shooting those maudlin romantic kiss shots with the bride and groom smooching in the center while the rest of the picture goes dreamy. You could try making one of your own center spots by smearing a small amount of hand soap in a circle around your skylight filter, avoiding the center of the lens.

Through rose colored glasses

Colored filters create the obvious effect of changing the color of the scene. A cool, blue mid morning shot of a ship at sea with the sun in the background can be turned to a glowing warm sunset shot with the addition of a sunset or orange filter. A blue filter will make the shot colder, almost arctic. Yellow, red, emerald, tobacco, mauve, pink, and coral are all popular colors for spicing up a dull old shot.

Sepia filters add a touch of warm brown to your images. Why would you want to do that? Old turn-of-the-century black-and-white photos had a sepia color to them. If you were shooting video tape of a black-and-white photo album, sepia color would give that familiar antique look to the image.

Although solid colored filters are inexpensive and quick to use, it is fairly easy to get along without many of them. If you bring colored sheets of paper with you on your shoot, you can white balance your camera aimed at one of the sheets. Make sure your camera's CONTINUOUS WHITE BALANCE is switched off so that your camera doesn't reset itself when you turn away from the colored page. The camera will now see the world with a tint opposite to the color on the page.

The same trick will work if you have a couple of colored filters and white balance your camera through the colored filter. When you remove the filter, the camera will see the world in a color contrary to your filter.

Filter tips

Less is better. Although you can stack filters, combining their effects, the added glass increases distortion, decreases brightness, contrast, and edge sharpness in your picture. The multilayers of glass may combine to create faint rainbows or Newton's Rings, and nets and star filters may combine to create moire, faint bands or shadowy dots across the picture. Use the fewest filters possible. Also don't forget that your camera may be adding its own filter to the equation. Switch the camera's filter wheel to CLEAR or OUTDOORS to remove it from the path. This is especially important when you are using 80A, 80B, or FLD correction filters.

Filter threads are delicate. Take care not to crossthread the filters when screwing them on. Also beware of glass thickness; you don't want to have any glass pressing against other glass as you tighten the filters. And tighten filters gently; you don't want them freezing up.

If you failed to heed the above caveat and cannot remove a seized filter, try these maneuvers: Screw your lens shade onto the filter. Put the lens cap on. Using the bigger "handle" of the lens shade (stiffened by the cap) and wrapping the web of your thumb around the filter/shade combo, give it a twist. The lens cap trick also works for unscrewing seized lens shades, especially the rubber kind. If that doesn't work, try this: Drape the filter with a tissue or rag to keep your sweat off the glass, then press your whole palm against the filter ring, leaving the ring's imprint in your palm. Now twist gently.

Mounted filters come in their own plastic boxes to keep them from getting scratched. Use the boxes. If you have so many filters that this is a problem, then screw them onto each other making a big stack. To protect the end filters, go to a camera store and buy metal caps to fit the rear threads and front threads of the last and first filter. "Stack Cap" is one brand name of caps. To use a filter, simply unscrew the drum at the right spot, remove the filter, then reattach the drum halves.

Anybody can shoot a picture. An expert works in many dimensions at once, some obvious and some subtle. By using filters, a mood can be created that adds dimension and realism to the story. Like a painter, the camera operator can exaggerate or tone down various parts of the picture, taking total control of the message. Considering the cost of all the electronics you can buy, and the learning curve you must endure to master these gadgets, filters are an easy way to make a big difference with a small budget.