Digital Darkroom

Three Essential Film Filters
Vs. Digital Filter Software

Tony Sweet  |  Jul 1, 2004

A lot has been made about filter use these days. There are those who use no filters at all, relying on the "natural look." Of course, with the various color biases of film, I'm not quite sure what film's natural look is. There are those who use filters liberally, subjectively altering and interpreting their images. And there are those who use filters sparingly. In the digital world, the questions are different. How do filters alter the digital image? Which ones work more accurately on the lens and which ones need to be applied using software?

Although I use film as my choice for image capture, I use digital workflow from when I scan the transparency to the finished product, be it a print or scanning images for an article or for a digital stock agency. During presentations, I'm often asked which filter I used on this or that image. I have about 20 filters that I use in my work, but only three are essential. I always tell students that they should add a filter to their arsenal only when they can verbalize at least one reason to do so.

The only filters that you really need to produce professional-level images are a warming filter, polarizing filter, and a graduated neutral density filter. In the following examples you will be presented with the original image shot on film, then the image using a glass filter, finally followed by the image with the filter applied digitally, using nik Color Efex Pro! (www.nikmultimedia.com).

Warming Effect
The filter that I use the most, by far, is the warming filter. It is used primarily in overcast light or in shade to remove the inherent blue or cold light from such scenes. As a result, an amber or warm tonality is added to the scene.

Here is the original scene shot in shade with no filter. Notice the overall blue cast of the image.

Here is the same image with an 81A glass filter placed on the lens. By removing the blue cast, the 81A adds a warm or amber tonality.

Here the warm effect is added in Photoshop using the nik Color Efex Pro! Brilliance/Warmth filter. This software filter has brilliance and warmth sliders which enable you to emulate various degrees of warmth. The equivalence in glass filters would be 81A, 81B, 81C, and 81EF. I was able to add an 81C effect to this image, which is more intense than the previous example using the 81A glass filter.

Polarizing Filter Effect
Polarizing filters are used primarily to remove glare and can darken a blue sky if used at approximately a 90Þ angle. Here's the shot on film without a polarizing filter. Notice how flat it is. The colors are actually very vibrant, but the glare is masking, or absorbing,
the color.

This scene is actually at a 90Þ angle to the sun, which is the best case for getting the maximum polarization, therefore greatest color saturation, and maximum blueness in the sky.

Polarizers take much more artificial intelligence than other digitally applied filters. Here is nik's Digital Polarization filter. It falls in between the two shots with and without a polarizing filter. Of course, more time at the computer working on selective color saturation would bring about a much closer version to the glass filter polarization. But, given the complex nature of digital polarization, nik's Digital Polarization filter is impressive! There are two controls where you can digitally rotate the polarizer and control the strength of the polarization.


Split Graduated Neutral Density
These filters are amazing in that they make images that are otherwise impossible to capture. These filters lower the contrast range by masking the highlights thus rendering detail in very dark and very bright areas, rather than blowing out the highlights or blackening shadows. The following examples are illustrative of using graduated neutral density filters.

The first two images are shot without the use of the graduated neutral density filter and illustrate the different results based on metering. On this first image, (above left) I metered the rock where the lighthouse is. As you can see, the foreground rocks and water are severely underexposed. On the next image, (above right) I metered the foreground water, severely overexposing the lighthouse rock.


Here is the final film version, using the Singh-Ray two-stop graduated neutral density filter. I metered the foreground rocks, as in the first example, (left) but handheld the grad filter over the lens until the finder appeared slightly darker over the lighthouse rock. As you can see, the exposure is now balanced to where you can see detail in the foreground dark area and the background lighthouse rock.

Here's the digital version (right) using nik's Graduated 0 Gray filter. The adjustments on this filter are amazing in that you can designate how far to have the filter drop down into the image. I found this very impressive. Controls include rotating the horizon (in the event that your bright area is at an angle); filter opacity (being the equivalent of a minus one-stop, two-stop, or three-stop filter); vertical shift (how far to bring the filter down into the frame); and blend. This is a really great tool for digital shooters, and for film shooters who forget their split neutral density filters!

So there you have it: the three essential filters for film and digital. For film, I recommend B+W's multi-coated warming filters, Nikon's polarizer, and Singh-Ray's split neutral density filters. For digital, the nik packages are unsurpassed. I was impressed at how nik's digital filters replicated glass filters used in film capture. The nik Color Efex Pro! packages have a wide range of filters and effects for digital and film shooters and are definitely worth checking out, especially the Photo Abstract Set.

Note to digital shooters: The polarizing filter can be used on your lens without any problems on any setting. Auto white balance will compensate for all filters placed on the lens, basically canceling out the desired effect. When shooting in raw mode, all filters will act as if you were using film, and the desired effect will be apparent.

Tony Sweet is a professional nature/fine art/stock photographer, author, workshop instructor, and lecturer living in Baltimore, Maryland. Visit his website at: http://tonysweet.com.

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