ExpoImaging ExpoDisc Reference Manual for Digital Cameras - Manual (Page 6)

ExpoDisc Instruction Manual
v. 4.0. 05/06
6
1.h.3. Studio Lighting
When using color balanced studio lighting, go to subject position and aim the camera
into the main light source for your custom white balance reading. You may need to aim
the camera back towards the tripod position if correcting for unbalanced illumination,
i.e. your lights do not emit the same color temperature light. Note, the strobe must fire
to set your custom white balance.
1.h.4. Direct On-Camera Flash
When using a flash unit mounted to the camera, you may get inconsistent results aiming
your camera and flash directly at the subject for your custom white balance capture. If
the color temperature of light coming from behind the subject is substantively different
than your daylight balanced flash illuminating the front of the subject, then the overall
white balance reading may shift. For example, indoor illumination is frequently warmer
in color than daylight balanced strobes. If the white balance capture is taken by aiming
the camera at the subject, then a subject backlit by warm tungsten light will signal the
camera to compensate and amplify the blue color channel. This may result in a bluish
colorcast on the subject.
Photographing in ambient light that is a similar color temperature to your camera-
mounted flash unit can yield acceptable results. For example, photographing in daylight
using daylight balanced strobes (5500K color temperature).
1.h.5. Wireless On-Camera Flash
If you are illuminating the subject with direct on-camera flash, and the flash unit can be
removed and remotely fired, then remove the flash and place it at your intended
shooting position. Then take your camera to your subject’s position and point the
camera back towards the flash unit to take your white balance reading. Note, the flash
must fire when taking the white balance capture.
1.h.6. Bounced (Reflected) On-Camera Flash
If utilizing bounce flash to illuminate your subject, then point the camera and flash
towards the bounce surface (e.g. ceiling) for your custom white balance capture. Note,
avoid aiming the camera towards a ceiling light.
You may get acceptable results reflecting the flash off a neutral, or near neutral surface
back towards the camera for the custom white balance capture. Note, non-neutral
surfaces will change the color of light they reflect. This may introduce a colorcast into
the image.
Bouncing the flash off a silver backed mirror may also produce acceptable results, but
mirrors with warmer or cooler tones may alter the light reflected back and affect the
results.
Whether bouncing flash off ceilings, walls, or mirrors, the degree to which the bounce
surface affects the results depends on the color of the surface itself. The closer the
surface is to neutral, the more accurate the color will be.