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Filters

If you talk to professional photographers who’ve gone completely, or almost completely, digital and ask them what kind of optical filters they use, they’ll probably snicker or smile. Most of these guys don’t use any optical filters at all, except maybe a Skylight or UV to protect some of their most expensive glass. They’re totally into the digital paradigm, treating their raw image files as matrixes to be enhanced and shaped in Photoshop before being output as prints or image files for their clients. With this mind-set, adding electronic plug-in filters to the mix makes a lot of sense, After all, these mini software programs let you add virtually any filter effects you want after taking the picture, as well as combine, layer, and partially erase these effects to transform images in ways that are virtually impossible with traditional glass optical filters. The real beauty of plug-in or software filters is that you can save each change, go back to any given point, or start all over again—all without altering your original image.

SOME DIGITAL FILTER CHOICES
The most popular plug-in filter system among pros is nik Color Efex Pro 2.0 ($299.95). It provides the most awesomely comprehensive filter set around, is easy to install on your computer, and comes with an easy-to-follow tutorial as well as excellent tech support. nik’s Pro 2.0 provides an incredible range of filter effects that include practically anything you can do with traditional filters plus many weird and wonderful creative effects that would be tough to duplicate in any other way. For more information, sample images, and to try them yourself, go to www.nikmultimedia.com. nik also offers less comprehensive, less costly versions of their software aimed at amateurs. Another good source for effective, easy-to-use plug-in filters is B+W of optical filter fame. There are currently two B+W Digital Filter sets available at $65 per set, each consisting of six different digital filters—the B+W Portrait & Family Set, or, for nature and landscape images, the B+W Outdoor set. For more info on B+W Digital Filter Sets go to www.schneideroptics.com and look under software filters tab. Both Nik and B+W plug-in filters can be used with Adobe Photoshop, Photoshop Elements and Corel Photo Paint, as well as other compatible picture-editing programs.

The before-and-after examples shown at the end of this article will give you a good idea of what you can do with these powerful creative tools, and why I believe they belong in any serious photographer's arsenal. However, while plug-in filters provide the ultimate in filtering flexibility, may be able to replace optical glass filters in some applications, and offer unique effects that are impossible or impractical to achieve by other means, there are still important things you can do with optical filters that actually filter the light before it reaches the image sensor or film.

OPTICAL FILTERS
For the vast majority of serious shooters out there who learned photography in the silver-halide era, the best news about optical filters is that virtually all of the filters you acquired for film photography will work in precisely the same way in digital applications. Just screw them onto your lens and you can accurately see the effect in the pentaprism viewfinders of digital SLRs as well as the electronic viewfinders (EVFs) used on most digital zoom-lens reflexes (ZLRs) with non-interchangeable zoom lenses. Optical filters will even work on your digital point-and-shoot if it has a threaded lens ring on front that lets you mount them. True, you won’t be able to see filter effects in the optical finder of a digital point-and-shoot, but you can get a pretty accurate picture of the effect by viewing each shot on the LCD after you take it, especially if your LCD is 2 inches or larger.

With the possible exception of color-conversion filters used for shooting tungsten film in daylight and vice-versa, which are not all that useful in digital photography, virtually any optical glass filter can be used effectively with your digital camera. Yes, this includes those classic medium yellow, light green and deep red filters you used to get more pleasing tonal gradation and dramatic skies when shooting black-and-white film. They’ll have the same effect when shooting in black-and-white mode with your digital camera. Indeed, all optical filters offer an elegantly effective, predictable way to get a wide variety of creative effects by simply screwing them in over your lens and taking the shot. No Photoshop or other image manipulation required, and you don’t even sacrifice the advantage of having an unfiltered image file for use later with plug-in filters ---just take a second shot without the filter!

The only caveat about using optical filters on digital cameras (or film cameras, for that matter) is that the diameter of the filter must be equal to or larger than the diameter of the lens you’re using it on. If it isn’t, you may get darkened corners or image edges (vignetting), especially in shots taken at wide-angle focal lengths. If the lens you’re using on a digital SLR is the same one you used with your 35mm SLR, your present optical filters may fit. If not, you can easily mount larger diameter filters on a smaller-front- diameter lens by getting an inexpensive step-up ring.

TRADITIONALIST OR A PRAGMATIST?
Perhaps the most significant distinction between optical and plug-in filters is, ahem, philosophical. Some photographers, including many traditionalists who are now shooting digital, prefer to create the image in camera at the moment of exposure, choosing to integrate the process of seeing the picture and capturing the final image as a seamless creative act. Others see the captured image primarily as a matrix upon which further creative effort is exerted at a future time. And of course many photographers are non-ideological pragmatists who will use either or both of these approaches, simply doing whatever they feel is required to achieve the final image they want. Well, one thing that you can’t do with plug-in filters—at least not practically while shooting in the field at present—is to preview the effect at the moment of exposure. This is easy with optical filters—just mount the filter over any camera with a through-the-lens viewing system and look through the finder. You can even use your digital camera’s LCD to check the result in the field, but you have to turn off the auto white balance to record any color effects accurately. Is this preview or instant feedback ability important? It depends on your working methods, but it sure can be.

Using optical filters also provides two essential technical advantages that are only possible by altering the light before it passes through the lens—true polarization, and compression of the lighting ratio. With a linear or circular polarizer, you can not only eliminate or attenuate glare on many surfaces (e.g. water or glass), but also see the actual subject details beneath the reflections you’ve eliminated. With a plug-in polarizer, there’s no way of getting the information hidden beneath the glare because the information was never recorded! Important? It depends on the subject—if you’re trying to capture the display in a store window or a bird in the water that’s been blown out by glare, a plug-in polarizer won’t cut it. Essentially, all a plug-in polarizer can do is to de-emphasize glare and enhance color contrast. Graduated plug-in filters have different restrictions. They work great in many cases, and they’ll give you practically any color or degree of gradation you want. However, if you’re using a graduated filter to compress the brightness range of a scene so that both highlight and shadow areas fall within the exposure latitude of the capture medium, you’re much better off with an optical graduated filter, which can give you, for example, cloud details in a bright sky while properly exposing the darker landscape. This is particularly important with digital image sensors, which are less tolerant of overexposure than, say, color print film.

THE BOTTOM LINE
Finally, to reiterate a point made at the beginning, glass filters can protect your expensive lenses. Both UV or Skylight 1A filters have little effect on color rendition or picture quality (both will remove a tad of bluishness in scenics shot at great distances or on cloudy days), but they sure will prevent rain, sand, dust and assorted sharp objects from damaging your prized optics. The bottom line: Both optical and electronic plug-in filters are essential tools that belong in the arsenal of any digital photographer—and any film photographer who scans his or her images. If you doubt this, just ask any working pro who shoots portraits, scenics, weddings, or art photography. So break out that dusty collection of optical filters lurking in your closet or gadget bag, wipe ‘em off with a micro fiber cloth, and give them a try on your new high tech digital camera, And by all means, check out plug-in software filters. If you’re not already a Photoshop junkie, these beauties can put you over the edge and into the wild zone.

SOME FILTER EFFECTS EXAMPLES