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expodisc
Professional Digital White Balance
Forward
Thank you for purchasing an ExpoDisc.
The ExpoDisc was originally designed by my late grandfather George A. Wallace as an
incident exposure and printing tool for use with 35mm SLR film cameras. But the
advent of the digital imaging revolution created an entirely new application for the
ExpoDisc by enabling photographers to quickly and easily manage their color at capture.
By now you already know that today’s Digital SLR cameras frequently do not reproduce
accurate color when presented with difficult real world lighting challenges. While many
cameras perform admirably in white light conditions, less ideal conditions, (e.g.,
tungsten, fluorescent, shade or stadium lighting) frequently require additional efforts be
taken to consistently deliver accurate color.
Factory defined white balance camera presets simply do not account for the multitude of
real life lighting variables found in almost every scene. And Auto White Balance is too
limited and inconsistent for most professional photographic applications.
Knowing the limitations of reflective metering, digital camera manufacturers allow for
photographers to measure, and correct for the color of incident light illuminating their
subjects through the custom white balance procedure.
A photographer using an ExpoDisc to set a custom white balance can quickly and easily
measure the color of incident light, and, in the process, provide his camera with the
information it needs to consistently capture and reproduce beautiful, accurate color.
From macro to telephoto to panoramic shooting applications, in studio, under tungsten,
in open shade and in mixed light environments, the ExpoDisc is simply the quickest and
easiest way to set a custom white balance.
We welcome you to visit our website at www.expoimaging.net for more information on
the ExpoDisc as well as other ExpoImaging products. There you will find updates on
cameras, additional instructions and helpful tips from the pros, not to mention a bit of
very colorful history on my grandfather George Wallace.
We hope you enjoy your ExpoDisc experience and welcome your feedback.
Sincerely,
Erik Sowder
President
ExpoImaging, Inc.
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TABLE OF CONTENTS
1. Getting Started
1.a. Introduction
1.b. What is a Custom White Balance
1.c. Neutral Filter vs. Portrait Filter (Warm Balance)
1.d. Custom White Balance for Digital Video
1.e. Overview of How to Set a Custom White Balance with the ExpoDisc
1.f. Installation of the ExpoDisc
1.g. Correctly Exposing the Custom White Balance Capture
1.h. Where to aim the Camera for the Custom White Balance Capture
1.h.1. Ambient/Mixed Lighting
1.h.2. Landscape Photography
1.h.3. Studio Lighting
1.h.4. Direct On-Camera Flash
1.h.5. Wireless On-Camera Flash
1.h.6. Bounced (Reflected) On-Camera Flash
1.i. Using the ExpoDisc with Other Camera Filters
1.j. White vs. Gray For Custom White Balance Reference
1.k. Poor Color Saturation
2. Advanced Users
2.a. Checking for Dust on the Digital Imaging Sensor
2.b. Applying an ExpoDisc Custom White Balance Post-Capture
2.b.1. Creating A Gray Frame Reference
2.b.2. JPEG Post Process White Balance Correction
2.b.3. Camera RAW Post Process White Balance Correction
2.c. Using a Custom White Balance to Create Warming and Cooling Effects
2.d. Metering for Exposure with the ExpoDisc
2.d.1. Front-lit subjects
2.d.2. Side-lit subjects
2.d.3. Back-lit subjects
3. Troubleshooting
3.a. Camera and Hardware Specific Issues
3.b. Camera Rejects the Custom White Balance Reading
3.c. Correcting for Colorcasts
3.d. Photographing in Mixed Light
Copyright Notice
Limited Warranty
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DIGITAL INSTRUCTIONS
1. Getting Started
1.a. Introduction
Thank you for purchasing the ExpoDisc. You are in possession of the finest “front-end”
white balance device for your color-managed workflow. Please treat the ExpoDisc as
any other fine optical instrument. When not in use, store the ExpoDisc in a dry, dark
place to ensure many years of use.
Before using your new ExpoDisc Neutral or Portrait Filter, please consult your camera
manual for specific instructions on how to set a custom white balance. To help you get
started, the Appendix contains step-by-step instructions for many DSLR cameras.
The following instructions apply to both the Neutral and Portrait ExpoDisc custom
white balance filters. The Neutral Filter will neutralize, or color balance the image file,
while the Portrait Filter will first neutralize the image, then warm it with a subtle red
cast ideal for skin tones.
IMPORTANT: Do not point your camera directly at the sun without the ExpoDisc
installed. Direct sunlight may damage or destroy your camera’s image sensor.
1.b. What is a Custom White Balance
Even the best digital cameras are incapable of consistently delivering accurate color
without the user performing a custom white balance. Auto (AWB) and preset white
balance functions often produce maddeningly inconsistent results.
Recognizing the importance of custom white balance to good color, digital camera
manufacturers have designed their cameras to take advantage of a custom white
balance. A custom white balance procedure captures, or samples the light with an
exposure, or reading of the light. An ExpoDisc custom white balance effectively
calibrates the camera to the color temperature of light to which the disc is exposed.
After following this procedure the white balanced camera neutralizes a colorcast by
amplifying the deficient red, green, and/or blue color channels to bring them into
balance with the highest value of red, green or blue appearing in the reference image.
Thereafter, the camera will add the same quantities of red, green and blue to any
pictures taken while the camera remains on that same custom white balance setting.
The result of using a custom white balance is balanced, accurate color.
1.c. Neutral Filter vs. Portrait Filter (Warm Balance)
The Neutral ExpoDisc is designed to pass equal amounts of red, green and blue light
through to the camera’s image sensor. The result of using the Neutral ExpoDisc to set a
custom white balance is balanced color -- white whites and gray grays.
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Designed specifically for portrait photographers, the ExpoDisc Portrait Filter enhances
and accentuates healthy skin tones. Rather than producing an image file with neutral
whites, the Portrait filter first neutralizes, then enhances the whole image with a
warming effect. The ExpoDisc Portrait Filter effectively adds subtle, pleasing red tones
and highlights to the hair and skin.
1.d. Custom White Balance for Digital Video
The ExpoDisc is an excellent white balance tool for use with digital video cameras.
Simply install the disc and follow your camera’s custom white balance procedure. The
instructions for where to point your video camera are the same as for still cameras (see
section 1.h. Where to Aim Your Camera). You must set a different custom white balance
for each change in lighting.
1.e. Overview of How to Set a Custom White Balance with the ExpoDisc
Install the ExpoDisc on the end of the lens and follow your camera’s custom white
balance procedure to take an exposure or reading through the disc. A custom white
balance can easily be set in any of the auto exposure (AE) modes, such as the “P”, “S”, or
“A” mode, or in the manual exposure “M” mode.
Under most conditions it is best to aim the camera towards the light source, as if you
were using an incident light meter to take the exposure or reading through the
ExpoDisc. Set your focus to manual if your camera will not release the shutter with the
ExpoDisc installed. Save or select the exposure, or reading (‘capture’) for your custom
white balance setting. This procedure must be repeated for each change in lighting.
The following sections provide additional in-depth information about each of the steps
involved with setting a custom white balance using the ExpoDisc.
1.f. Installation of the ExpoDisc
Insert the ExpoDisc into the threaded recess in front of your camera lens with the plain
white side facing the camera. To remove the ExpoDisc, simply reverse this action.
1.g. Correctly Exposing the Custom White Balance Capture
Whether photographing in the manual exposure “M” mode, or one of the auto exposure
“AE” modes, the custom white balance capture should be taken with correct exposure
settings for the shot. Failure to do so may result in the inability to set a correct white
balance.
Your white balance capture will be automatically exposed correctly if you use the
camera’s auto exposure (AE) settings, such as the “P”, “S”, or “A” modes.
When using the manual exposure “M” mode, set the custom white balance with a
properly metered exposure. Shoot the custom white balance capture at the same
exposure setting as was metered for the shot.
1. Take an incident flash-meter reading (or equivalent) to get a correct exposure.
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2. Set the indicated exposure with the camera in the “M” manual exposure mode.
3. Take an exposure, or reading through the ExpoDisc to set the custom white
balance. (See 1.f. Where to Aim the camera.)
If your camera does not capture an image in the custom white balance procedure, e.g.
Nikon cameras, then you may want to take an additional exposure through the ExpoDisc
to examine its histogram.
Examine the in-camera histogram of the ExpoDisc image file to verify the exposure is
not clipped in either the highlight or shadow areas. If the histogram appears acceptable,
then you have an acceptable exposure for custom white-balance purposes.
Note. Setting a custom white balance under strobe illumination at an exposure setting
other than that with which you will photograph your subject may produce an incorrect
white balance and colorcast. The difference in exposure could alter the ratio of ambient
light to strobe light, which would effectively change the color temperature of your
custom white balance exposure.
1.h. Where to Aim the Camera for the Custom White Balance Capture
Using the ExpoDisc to set an accurate custom white balance requires the light
illuminating the subject to pass through the ExpoDisc to your camera’s image sensor.
This is easily accomplished in studio, under ambient light, and in certain on-camera
flash applications. Point the camera towards the main light source in studio, or under
ambient light in a direction that will capture the direct and reflected light illuminating
the subject for the custom white balance capture.
1.h.1 Ambient/Mixed Lighting
Point the camera in a direction that allows the light you wish to balance (the light
illuminating your photographic subject) to strike the front of the ExpoDisc. In other
words, stand in similar lighting as your subject and point the camera back towards the
position from which you will take the picture. Using this technique will allow you to
balance the average color temperature of ambient light illuminating your subject,
including light reflected off nearby surfaces, e.g. green lawn, red brick patio, brightly
colored walls, etc.
1.h.2. Landscape Photography
Although the ExpoDisc is an incident tool, the landscape photographer will find it
invaluable in correcting for extreme lighting conditions, e.g. snow scenes, high
elevations, early evenings, etc. Because a landscape photographer’s subject is a vista
encompassing many color temperatures of light, it is impossible to balance to a single
light source. Therefore, it is best to balance to the scene itself, by aiming the camera
towards the scene to be photographed. This technique allows the camera to establish an
average color temperature for the scene, and to preserve the varying shift in warmer and
cooler tones throughout the scene.
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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 cameramounted 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.
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1.i. Using the ExpoDisc with Other Camera Filters
The ExpoDisc generally can be installed and used as intended over other camera filters,
such as skylight, UV, or polarizing filters. Some users have experienced inconsistent
results when using the ExpoDisc with a UV/IR ‘cut’ filter, however.
Note that any color introduced by filters combined with the ExpoDisc during the custom
white balance procedure will be neutralized (unless the color temperature is outside the
range of your camera’s capabilities, see Poor Color Saturation 1.j. below)
1.j. White vs. Gray for the Custom White Balance Reference
Digital cameras require a neutral surface, white or gray, to set an accurate custom white
balance. But while both white and gray may produce an accurate white balance, a
middle gray value is easier to use and more desirable. This is because a middle gray
medium reduces unwanted reflectivity and the danger of overexposure, problems
frequently associated with use of bright, white surfaces. As such, the calibrated
neutrality and light density (18% gray) of the ExpoDisc make it an ideal white balancing
tool. Therefore, even if your camera’s manual specifies the use of a white reference, the
ExpoDisc will function correctly with your camera.
1.k. Poor Color Saturation
The ExpoDisc works by alerting the camera’s white balance sensors to color(s) that need
to be increased in order to achieve a neutral balance. Most digital cameras can establish
a correct white balance when the source light is in the range of 2800˚ to 9500˚ degrees
Kelvin. Your camera may not be able to set a white balance when the color of the source
light is outside this range, or it may display a warning message such as ‘over’, ‘under’, or
‘out of range’. In some cases, either the maximum or minimum color temperature will
be used as the white balance, which may result in a color cast in your pictures.
2. Advanced Users
2.a. Checking for Dust on the Digital Imaging Sensor
To check for dust on your DSLR’s digital imaging sensor, simply install the ExpoDisc,
place the camera in aperture priority mode and set the aperture to f16. Put the camera
in manual focus mode, aim at any light source, zoom out and focus on infinity. Press the
shutter release to capture a dust reference frame.
If you see dust spots on the dust reference image, then you need to clean your camera’s
imaging sensor. Consult your camera’s manual for proper instructions.
2.b. Applying an ExpoDisc Custom White Balance Post-Capture
When used as described in Sections 1.d through 1.j, your digital camera will record an
ExpoDisc custom white balance with JPEG and RAW image files when you shoot. This
is critical with JPEG files since white balance is applied at the time of image capture and
adjusting for incorrect white balance is difficult, if not impossible, post-capture.
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A white balance recorded at capture with RAW files is also extremely convenient since
the RAW files will be imported with an accurate ‘As Shot’ white balance. Although the
ExpoDisc excels at performing in-camera white balance, it can also be used effectively to
set white balance post-capture.
‘As Shot’ White Balance Applied to RAW Images Post Capture
Unlike JPEG files, RAW image files store white balance data separately from other
image data, allowing you to apply any one of multiple white balance settings postcapture. You can easily apply your ExpoDisc white balance taken at capture to RAW
images as the ‘As Shot’ or ‘Shot Settings’ white balance.
If, while capturing your images in RAW, you took a custom white balance reading with
the ExpoDisc and applied that reading to each image using the procedures described in
Sections 1.d through 1.j, each image will have the ExpoDisc custom white balance
assigned to the ‘As Shot’ white balance setting for that image. When the image is
opened in your RAW image manipulation plug-in or program, (e.g., Adobe Photoshop®
RAW plug-in, Nikon® RAW Plug-in, Nikon Capture®, Canon® RAW Image Converter,
Apple Aperture®, Adobe Lightroom®, etc.) the ‘As Shot’ option in your RAW image
software will refer to the ExpoDisc custom white balance recorded with that image.
Therefore, when you open your RAW image file, just select the ‘As Shot’ option and your
image will open with your ExpoDisc custom white balance applied. You can evaluate
your ExpoDisc custom white balance to other white balance presets (e.g., Sunlight,
Fluorescent, Tungsten, etc.) by selecting one of those options and comparing it to the ‘As
Shot’ ExpoDisc custom white balance.
Click Balance: Post-Capture White Balance Application Without Applying a Custom
White Balance In Camera at the Time of Shooting
The ExpoDisc can also be used to create white balance reference frames which can later
be applied post-capture in Adobe Photoshop®. Although in most situations it is
advantageous to apply a custom white balance at capture, it is possible to record a
custom white balance capture, take multiple shots without applying that reference in
camera, then apply that custom white balance reference post-capture in Photoshop®.
This post-capture white balance application is commonly called ‘click-balancing’.
Sections 2.c.1 through 2.c.3, which describe a post-capture ‘click-balance’ procedure for
the ExpoDisc, were graciously contributed by photographer Peg Jackson. Whether you
will be shooting JPEG or RAW, shoot your images and create a gray frame reference
using the procedures described in Section 2.c.1. Then, follow the procedure outlined in
2.c.2 if you are shooting JPEG or the procedure in 2.c.3 if you are shooting RAW. By
‘click-balancing’ using Peg Jackson’s method, you will apply your ExpoDisc custom
white balance reference frame to images post-capture.
2.b.1. CREATING A Gray Frame Reference for Post Process
Set your camera’s white balance preset control to match the dominant light source in the
scene, e.g. use ‘Daylight’ if it’s sunny, ‘Cloudy’ if it’s overcast, ‘Tungsten’ for
incandescent lighting, ‘Fluorescent’ for fluorescent, etc. and, following the procedures
for using the ExpoDisc, capture an image, or reading. This will record a “gray” frame
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reference that documents the color of the light where the exposure is made. Shoot your
pictures using the same white balance preset.
Note that the ExpoDisc Gray Frame Reference is only truly gray if you aim the camera
towards white light; it will appear blue if you aim the camera towards blue light, and
orange if you aim the camera towards yellow light, etc. This colorcast is what the camera
or software neutralizes in the white balance procedure.
You may also notice slight variations in color by clicking on different areas of the gray
frame. These variances in the RGB values may result from a combination of image
processing, lens fall-off, dust contamination, sensor imperfections, or artifacts
introduced by compression programs including conversion of files to other formats such
as JPEG. To minimize the possibility of encountering such variations, your eyedropper
tool sample size should be set to 3x3 or 5x5. To set the sample size select the eyedropper
tool in the Tools palette and change the sample size on the Option bar.
2.b.2. JPEG Post Process White Balance Correction
1. Open the Gray Frame Reference in Adobe® Photoshop® and open the photo you
want to correct, so you have both images side by side. Click on the Gray Frame image to
make it active.
2. Click on the New Adjustment Layer icon at the bottom of the Layers palette.
3. Click on Curves.
4. The Curves dialog box will open. Click on the Gray eyedropper, and then click on the
Gray Frame reference image. This will neutralize the color. Click OK. You’ll see the
Curves Adjustment Layer above the Background Layer in the Layers palette.
5. By looking at the Info Palette you can see that the RGB values are equal and the color
is neutralized.
6. Now, the fun part! Click on the Curves Adjustment layer in the Layers Palette, hold
down the mouse button and drag the Adjustment Layer onto the photo you want to
correct. This applies the neutral adjustment layer, ie. The White Balance, to the photo.
You’ll see the Curves Adjustment layer over the Background layer in the Layers Palette.
7. You can click and drag the Curves Adjustment Layer to the rest of your images taken
under the same lighting conditions, or use the Batch feature to apply the adjustment to
all the images in the folder.
2.b.3. Camera RAW Post Process White Balance Correction
1. Open the Gray Frame Reference in Adobe® Camera Raw.
2. Settings should be set to “Camera Default” and White Balance to “As Shot”.
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3. When the RGB values at the bottom of the screen are within a point or two of each
other the white balance is nearly perfect. When the numbers are significantly different
the image has a colorcast. Equal numbers mean a perfectly neutral White Balance.
4. If the RGB numbers don’t match, then click on the White Balance Tool (the
eyedropper) and then click on the Gray Frame Reference. This will neutralize the color,
and the RGB values will now be equal. Click OK.
5. Open the next photo in Camera Raw. Instead of “Camera Default” change the setting
to “Previous Conversion”. This will apply the neutral White Balance setting established
by the Gray Frame Reference.
6. Adjust the Exposure and Shadow settings for the photo, and click OK. You can open
the rest of your images taken under the same lighting conditions using “Previous
Conversion” individually, or use the Batch feature to apply these settings to all the
images in the folder.
“Many professional labs will do color correction for you, and they can only give you the
best quality prints from image files that are properly exposed and require little color
correction. Using the ExpoDisc will help ensure both consistency and neutrality.”
-Peg Jackson.
2.c. Using a Custom White Balance to Create Warming and Cooling
Effects
You can modify your ExpoDisc custom white balance by placing a colored filter over the
front of the ExpoDisc during the custom white balance procedure. This will create a
custom color profile that adds a colorcast inverse to the color of the filter placed in front
of the ExpoDisc. For example, using a yellow filter in front of the ExpoDisc will create a
cyan cast to all images to which that custom white balance is applied. Note that the
warming and cooling filters are used only when the custom white balance captures are
made. The actual photo is shot without any colored filters.
In this fashion, the ExpoDisc can be used with Kodak Wratten Series warming and
cooling filters to provide the traditional look of film warming and cooling with digital
capture.
For a warming series, shoot balance captures with the bluish 82, 82A, 82B and 82C
filters. When the custom white balance procedure removes the excess blue of these
captures to normally exposed images, the compliment of the 82 series will be “applied”
to the normally exposed images, thereby resulting in 81, 81A, 81B or 81C warming
effects.
For a cooling effect on your normally exposed images, shoot balance captures with the
warm looking 81, 81A, 81B, and 81C filters. When the custom white balance procedure
removes the excess warming effect of these filters, the compliment of the 81 series will
be applied to the normally exposed images, thereby resulting in an 82, 82A, 82B or 82C
cooling effect.
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2.d. Metering for Exposure with the ExpoDisc
Today’s digital SLR cameras capture an image with a similar dynamic range as
yesterday’s Kodachrome 64 color slide film, for which the ExpoDisc was originally
designed. The method for using the ExpoDisc as an incident exposure tool was initially
developed to compensate for the limited dynamic range of the capture medium. The
result is a tool that requires decisions over whether to expose for highlights or shadows
in high contrast lighting, and to make adjustments as necessary. When used correctly,
you should expect to be within 1/3 stop of correct exposure.
2.d.1. Front-lit Subjects
This category includes all front-lit and uniformly-lit subjects and scenes in which there
are no significant highlight or shadow areas.
1. Stand in the same lighting as your subject (although not necessarily beside it) and put
your camera in its manual exposure mode and mount your ExpoDisc in front of the
camera.
2. Then point the camera and ExpoDisc in the direction directly opposite that in which
you will be shooting to make the exposure.
3. Turn on the camera meter, adjust the aperture and/or shutter speed settings until the
camera meter indicates good exposure conditions.
4. Return to your shooting position (if you left it to do your metering) and remove the
ExpoDisc from in front of the camera lens.
5. Aim the camera, check the framing, and shoot.
2.d.2. Side-lit Subjects
These include all subjects and scenes in which there are significant highlight and
shadow areas, and in which the highlight areas are most important.
Follow the procedure described for photographing front-lit subjects, but after pointing
your camera and ExpoDisc directly away from the subject and before adjusting the
exposure settings, swing the camera and ExpoDisc about one-third of the way towards
the main light source.
2.d.3. Back-lit Subjects
This category includes all subjects and scenes in which there are significant highlight
and shadow areas, and in which the shadow areas are most important.
Follow the procedure described for photographing front-lit subjects, but just before
clicking the shutter, reduce the exposure one full stop, to provide for appropriately
darker-than-normal image tones in the shadow areas.
3. Troubleshooting
3.a. Camera and Hardware Specific Issues
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Check the camera’s instruction manual to ensure you are correctly following the custom
white balance procedure. Simple procedural errors frequently lead to inconsistent
results and colorcasts. User defined camera settings can also affect results, such as
color, tone and hue. Firmware updates, monitor calibration and print settings should
also be considered and evaluated when troubleshooting color problems.
3.b. Camera Rejects the Custom White Balance Reading
If a digital camera takes a reading without taking an exposure (e.g., Nikon, Fuji, etc.) in
the custom white balance procedure, then the camera may reject the reading (No Good)
if the custom white balance capture is over, or under exposed. If this rejection occurs,
then adjust the exposure and repeat the custom white balance procedure until the
camera accepts the reading.
The camera may also reject the custom white balance reading if the color temperature of
light is outside the range and capability of the camera to balance (No Good, Over/Under
Error). See 1.k. Poor Color Saturation. Modify the color temperature of light to bring it
within the specified custom white balance range of the camera.
3.c. Correcting for Colorcasts
Because the ExpoDisc is a professional tool it must be treated like any other professional
tool, with a proper respect of what it can do when used properly, and what can result if
used improperly.
Taking a picture with an improper white balance will yield an undesirable colorcast.
Red, Green, Blue, Cyan, Magenta or Yellow colorcasts may result from improper use of
the ExpoDisc. Most colorcasts result from improperly aiming the camera while setting
the custom white balance, or from failing to properly follow the camera’s custom white
balance procedures.
In general, a bluish colorcast will appear in the image if the custom white balance
capture incorporated warmer light than that which illuminated the subject at the time of
image capture. Conversely, a red or yellow colorcast will occur if the custom white
balance was set to a cooler light source than that which illuminated the subject at the
time of image capture.
3.d. Photographing in Mixed Light
White balance settings are stored as color temperatures, and digital cameras are limited
to setting a single white balance color temperature for any given shot. Using an
ExpoDisc, a photographer can set a single white balance to an average color temperature
of two or more divergent light sources. However, an individual light source may still
dominate the color of light illuminating particular portions of an image. To the extent
that any portion of an image is illuminated by light that differs from the camera’s set
white balance, that portion may show a colorcast.
In a diffused mixed light environment, aim the camera in a direction that will expose the
ExpoDisc to the multiple light sources during the custom white balance capture.
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Usually, standing at the subject position and aiming the camera back towards your
intended shooting position will incorporate the multiple mixed light sources
illuminating your subject. The result will be a white balance that represents the average
color temperature of light illuminating the exact location of the camera and ExpoDisc.
Minimizing the effect of selective colorcasts resulting from dominant unbalanced light
requires some artistic choices. Using color balanced lights will minimize the visible
colorcast created by any individual light source. Increasing the distance between the
subject and a light source will diffuse and subsequently reduce the intensity and
influence of a single color temperature light on the subject.
A photographer can also choose to enhance, or minimize a colorcast when shooting in a
mixed light environment by adjusting where the camera is pointed for the custom white
balance capture. If choosing between a warmer and cooler light source, it is
recommended that you set the custom white balance to the cooler light source. This will
result in a slightly warmer image. Balancing to a warmer light source in the presence of
a cooler light source will result in a cooler image.
If the introduction of white flash light (5500K) into a warm ambient light environment
caused a bluish colorcast, then it may be possible to modify the output of the flash unit
to the ambient color temperature light source by using gels on the flash/fill lights. For
example, use an 85 gel over the flash to match incandescent light, or a 30 green to
match fluorescent light.
Copyright Notice
All rights reserved. No part of this publication may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without the prior written permission of
ExpoImaging, Inc. The information contained herein is designed only for use with this
ExpoImaging, Inc. product. ExpoImaging, Inc. is not responsible for any use of this
information as applied to other equipment.
ExpoImaging, Inc. shall not be liable to the purchaser of this product or third parties for
damages, losses, costs, or expenses incurred by purchaser or third parties as a result of:
accident, misuse, or abuse of this product or unauthorized modifications, repairs, or
alterations to this product, or failure to strictly comply with ExpoImaging, Inc.
instructions for use.
Trademarks
ExpoDisc and ExpoImaging are trademarks of ExpoImaging, Inc.
General Notice: Other product names used herein are for identification purposes only
and may be trademarks of their respective owners. ExpoImaging, Inc. disclaims any and
all rights in those marks.
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© 2006 ExpoImaging, Inc.
05/06
ExpoImaging, Inc., Limited Warranty
What Is Covered: ExpoImaging, Inc. (“ExpoDisc”) warrants to the original retail
purchaser that the ExpoDisc filter covered by this limited warranty statement, conforms
to the manufacturer’s specifications and will be free from defects in workmanship and
materials for a period of one (1) year from the date of original purchase. For warranty
service, you must provide proof of the date of original purchase.
What ExpoImaging, Inc. Will Do To Correct Problems: Should your ExpoDisc filter
prove to be defective during the warranty period, please call ExpoImaging, Inc.
Technical Support at (408) 778-2040 for warranty repair instructions and return
authorization. An ExpoImaging, Inc. service technician will provide telephone
diagnostic service to determine whether the product requires service. If service is
needed, ExpoImaging, Inc. will exchange the product without charge. ExpoImaging, Inc.
will ship a replacement filter to you, freight prepaid. You are responsible for securely
packaging the defective filter and returning it to ExpoImaging, Inc. within ten (10)
working days of receipt of the replacement. Expo-Imaging, Inc. requires a debit or a
credit card number to secure the cost of the replacement product in the event that you
fail to return the defective one. The item replaced becomes ExpoImaging, Inc. property.
The replacement filter may be new or refurbished to the Expo-Imaging, Inc. standard of
quality, and, at ExpoImaging, Inc.’s option, may be another model of like kind and
quality. ExpoImaging, Inc.’s liability for replacement of the covered filter will not exceed
the original retail sales price of the covered filter. Exchange filters assume the remaining
warranty period of your original product covered by this limited warranty.
What This Warranty Does Not Cover: This warranty covers only normal use. This
warranty is not transferable. ExpoImaging, Inc. is not responsible for warranty service
should the ExpoDisc label or logo be removed or should the filter fail to be properly
maintained or fail to function properly as a result of misuse, abuse, improper
installation, neglect, improper shipping, damage caused by disasters such as fire, flood,
or service other than by ExpoImaging, Inc.
THE WARRANTY AND REMEDY PROVIDED ABOVE ARE EXCLUSIVE AND IN LIEU
OF ALL OTHER EXPRESS OR IMPLIED WARRANTIES INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT OR FITNESS FOR A PARTICULAR PURPOSE. SOME LAWS DO
NOT ALLOW THE EXCLUSION OF IMPLIED WARRANTIES. IF THESE LAWS
APPLY, THEN ALL EXPRESS AND IMPLIED WARRANTIES ARE LIMITED TO THE
WARRANTY PERIOD IDENTIFIED ABOVE. UNLESS STATED HEREIN, ANY
STATEMENT OR REPRESENTATIONS MADE BY ANY OTHER PERSON OR FIRM
ARE VOID. EXCEPT AS PROVIDED IN THIS WRITTEN WARRANTY,
EXPOIMAGING, INC., SHALL NOT BE LIABLE FOR ANY LOSS, INCONVENIENCE,
OR DAMAGE, INCLUDING DIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL
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DAMAGES, RESULTING FROM THE USE OR INABILITY TO USE THE EXPODISC
PRODUCT, WHETHER RESULTING FROM BREACH OF WARRANTY OR ANY
OTHER LEGAL THEORY.
Some jurisdictions do not allow limitations on how long an implied warranty lasts, and
some jurisdictions do not allow the exclusion or limitation of incidental or consequential
damages, so the above limitations and exclusions may not apply to you. This warranty
gives you specific legal rights and you may have other rights which vary from
jurisdiction to jurisdiction.
ExpoImaging, Inc., 365 Woodview Avenue, Suite 700, Morgan Hill, CA 95037-2840
v 4.0. Copyright © 2006 - ExpoImaging, Inc. All rights reserved.
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