October 20, 2017

Filters for Digital Photography

In the days when photographers shot slide (transparency) film, they recorded accurate color under daylight (sunny) conditions. If they needed to compensate for the blue of overcast skies or the orange of incandescent light bulbs, they had to attach a color correction filter to fix the color cast. If they used print (negative) film, color was corrected in the printing process.

No Color Filters Necessary

In your digital camera, the White Balance settings take care of this color correction for you. Instead of adding an 81 series warming (yellow) filter to your lens to correct a blue color cast, change the White Balance setting to Cloudy or Shade. This adds yellow to cancel the blue.

Cloudy skies create a blue color cast.

Using Cloudy White Balance removes the blue cast without a filter.

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Instead of attaching an 80 series cooling (blue) filter to fix an orange color cast (such as from incandescent light bulbs), switch the White Balance to the Tungsten or Incandescent setting. This choice adds blue to correct the orange cast.

Incandescent lights create an orange color cast.

Using Incandescent White Balance removes
the orange cast without using a filter.
 
If you do want to use color filters with your digital camera, you need to set the White Balance to Daylight/Sunny to prevent the camera's automatic White Balance from removing the color of the filter itself.

Polarizing Filters Are Useful

Some filters are still helpful for digital photography. One is a circular polarizing filter for landscape photography. A polarizing filter reduces glare and reflections on leaves, wet rocks, water surfaces and the scattered light in the sky to bring out the colors of your subjects. You can see this effect through the viewfinder or on the LCD screen before you take the photo. And you can adjust the polarizing effect by turning the outer filter ring. (Be careful that you don't unscrew the filter itself!)

Without a polarizing filter, the sky is pale and clouds faded.

With a polarizing filter, the sky is more colorful and the clouds pop out.

A polarizing filter is dark and blocks light, so it can sometimes also help to give you a slower shutter speed for creative blur effects (think flowing water). However, because it's dark, you don't want to keep this filter on your lens all the time.

UV Filter Versus a Lens Cap

UV or Skylight filters are basically clear and don't have any color correction or other effect on your picture. They can serve to protect your lens from dust and salt spray, for instance, but they don't have a visible effect on your images. If you use one of these filters, you should take it off before adding a second filter (such as a polarizer) to prevent vignetting. Vignetting is dark edges in your photos due to the lens seeing the sides of the stacked filters.

Personally, I do not use a UV filter unless I'm shooting in harsh conditions, such as a dusty rodeo or along the ocean coast where there is salt spray. I use a lens cap to protect my lenses.

So put aside the color filters that were useful when we were shooting slide film and rely on your camera's White Balance controls and a polarizing filter instead.

Learn these and other useful techniques in my photography classes at the Lifelong Learning Center in Missoula, Montana. New classes are starting in November. Click here to register.