Datasheet

c h a p t e r 1: DIGITAL IMAGING BASICS, WORKFLOW, AND CALIBRATION ■

If you do not have the opportunity to shoot a gray card, you can select a

default from the White Balance drop-down in the Adjust tab (ACR) or the Basic pane

(Lightroom) or you can accept the As Shot settings; however, a gray card takes all the

guesswork out of the color and can save a lot of post production, especially if you are

working with a large volume of images.

Calibration Review

The testing procedure consists of shooting the test target in a controlled manner, cap-

turing a wide range of under-, normal-, and overexposures to see exactly the limits of

the camera capturing capabilities. Ideal exposure is determined with numeric precision

so that the maximum amount of useable data is available for post-capture manipula-

tion in software. Under- and overexposure limits are similarly determined so that you

know how far you can go with a particular important tone in an image. The goal is

to be able to give the maximum useable exposure and thus ensure that you have the

cleanest, most noise-free information in the captured image.

Once you have a good exposure of the test target, color calibration is accom-

plished using software in an automated fashion. Remember that color is not nearly

as critical as value or tone. Ideal color is fairly subjective, and the photographer will

be compelled to interpret and adjust for creative effect after the image is captured.

However, it makes sense to start from a neutral unbiased point and so the color cali-

bration step should be included—just don’t lose sleep worrying about how accurate

your color is.

Testing Procedure Overview

The testing procedure breaks down into the following items:

S• hoot an X-Rite ColorChecker 24 Patch Classic target in shade and tungsten

lighting.

M• easure a mid-gray reference of 18 percent and open

⁄

to determine base

exposure.

B• racket around the expected normal exposure—two stops under and two

stops over.

I• ncrement exposures by

⁄

stop, using shutter speed if possible.

C• hange the E.I. reference on a card in the shot to reflect the change for expo-

sure (100, 80, 64, 50 for +

⁄

exp).

I• mport files into Lightroom or ACR with Zero slider settings.

E• valuate the exposure sequence for the ideal exposure.

U• se this information to enter an exposure compensation factor in the camera

or as an E.I. setting in a hand-held light meter.

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