Digital SLR Superguide: Using a dSLR
Understanding the inner workings of dSLRs Using a dSLR is not just about knowing the basics of photography and applying them. While that is vital, it is also important that you understand a little of what is going on inside the camera, and how to take advantage of it. Once you have mastered this then you can really start to get creative.  Hazy about "white balance" Setting manual white balance The meat on RAW Having fun with white balance
Hazy about "white balance"
Film users will be familiar with the principle of using filters to correct for different light types. For example, incandescent (tungsten) or fluorescent lighting will need to have different filters so that the colors come out true. The reason this is so is due to the fact that different light types give off slightly different colors of light. The human eye can adjust to this so we don’t notice, but cameras record the different colors. This is what is called a "color temperature".
A low color temperature shifts light toward the red (i.e. warmer) while a high color temperature shifts light toward blue tones (i.e. cooler). Different light sources emit light at different color temperatures, and thus the color cast. These affect the way that the camera captures the colors of the object that you are shooting. Most people don’t bother with the filters and so their indoor pictures invariably come out with a yellow/orange orbluish cast. In the digital world, these correction filters are no longer necessary as they are replaced by a feature found in most digital cameras called "white balance". Normally the human eye can compensate for lighting conditions with different color temperatures. However, a digital camera needs to find a reference point that represents white. It will then calculate all the other colors based on this white point. For instance, if a halogen light illuminates a white wall, the wall will have a yellow cast in the picture when, in fact, it should be white. So if the camera knows the wall is supposed to be white, it will then compensate all the other colors in the scene accordingly.
Setting white balance manually
 To set the white balance manually it is necessary to tell the camera which object in the frame is actually pure white (or as close as can be). This allows the software inside the camera to make adjustments to ensure that all the colors are recorded accurately.
Most digital cameras allow the white balance to be set manually. Digital SLR cameras allow you to define your own white balance reference. Before making the actual shot, you can focus at an area in the scene that should be white or neutral gray, or at a white or gray target card. The camera will then use this reference when making the actual shot. Refer to your camera manual for the procedures to carry out custom white balance settings. Ideally, for precise measurements, an accurate reference device would be a Kodak gray card (which is calibrated to 18 percent gray--the basis of most exposure meters in cameras) or an Expodisk. However, out in the field, there’s often no time to do a pre-shoot measurement, and a rough gauge will have to suffice. Use any relatively white area, such as a blank sheet of white paper. Once you’ve selected a white balance setting, just remember to reset this setting when you head back outdoors into natural light, or you may end up with some strange tones and hues to your subsequent images. | |||||||||
Using a dSLR- Talkback
-
There are currently no comments for this story.
To post comments, you need to become a member. It's FREE.
