Datasheet

12
c h a p t e r 1: DIGITAL IMAGING BASICS, WORKFLOW, AND CALIBRATION ■
The testing procedure involves a series of steps, which are summarized here:
1. Establish lighting that mimics the conditions for 6500º K and 2850º K—open
shade and tungsten lights indoors.
2. Shoot a range of exposures to determine your camera E.I. (exposure index,
ISO, or ASA rating).
3. Import RAW files into Lightroom or ACR, and white balance to the light-gray
patch.
4. View the series of exposures in Lightroom or ACR and apply “Zero slider”
settings.
5. Identify the best exposure by comparing the exposures and reading numbers
from the mid-gray patch.
6. Convert the best exposures to DNG.
7. Open the two DNGs representing 6500º K and 2850º K color temperatures into
Adobe’s DNG Profile Editor or X-Rite’s ColorChecker Passport software and
build camera profiles.
8. Save your settings and create a new “camera default” setting for your camera.
Establishing Lighting
You should shoot your test exposures under conditions as close as possible to 6500° K
(open shade) and 2800° K (regular incandescent or halogen lights) color tempera-
tures—two complete test sequences. If you shoot mostly outside, you’ll also want to
set up and test outdoors using direct sunlight as well. To cover all your bases, you
might want to calibrate for other unusual lighting conditions. Here are some consider-
ations for various lighting conditions.
Outdoor Daylight Try to set up in broad daylight under clear sky conditions. Make sure
that no shadows hit your target—especially the ColorChecker. Stay away from build-
ings as much as possible to minimize the effect of reflected light on your test—if you
set up near an orange-colored wall, it will affect the color.
Outdoor Open Shade Set up your test subject in open shade in an area that is illuminated
by a broad expanse of blue sky. Try not to set up under trees because light filtering
through green leaves will pollute the color temperature.
Indoor Incandescent Lighting If possible, use a single light positioned at a 45-degree
angle to the target and about 10 feet away. Make sure you’re in a room with white or
neutral colored walls. Aim for as even illumination as possible—again, make sure no
shadows hit the target. You can use a higher ISO setting on the camera to bring the
exposure within range, but try not to go above an E.I. of 800.
Studio Flash Lighting This is very similar in character to daylight, but here you want to
simulate your most common lighting. Use the lighting you normally use for your sub-
jects: use the same umbrellas or other light modifiers. Don’t do anything special just
for the test. If you use two lights, make sure they are the same type or make. You can
skip any hair lights and just concentrate on your front lighting.
592120c01.indd 12 6/17/10 9:49:52 AM