Custom white balance & Colorchecker Passport - how do you...?

[celeste_adine]

<p>I do outdoor portraits with a speedlight and softbox plus Colorchecker Passport. I know how to set a custom white balance in my camera but there are a couple of things I'm confused about. </p>

<p>I often put a subject in open shade and usually have a brighter area in the background where there is light coming through the trees and lighting up leaves and a grassy area behind the subject. After I balance my flash on the subject to the ambient light, I set the white balance by having my subject hold the white card part of the Colorchecker Passport. It's so small, I have to take my camera off the tripod an approach the white card. I photograph it using the same flash setting that will be used when I photograph my subject. </p>

<p>1st question: when photographing the white card, I usually have to change the shutter speed or else the flash blows out part of the white card. (I'm puzzled by this since the flash does not blow out on my subject.) I've now got one exposure for my scene and subject with flash, and a different exposure for the white card. Is that ok, or will the different exposure for the white card make the resulting custom white balance invalid for the settings I plan to use to photograph my subject?</p>

<p>2nd question: my understanding is that when photographing a white card for a custom white balance, the card should fill the frame. But there's no way I can get that small white card in the Colorchecker Passport to fill the frame. That means I'm creating a custom white balance with the white card plus whatever else happened to around the edges of the white card when I photographed it. Does that other stuff affect my custom white balance? If so, (this is rhetorical) why is the white card in the Colorchecker Passport so small if it cannot reasonably be used to create a custom white balance?</p>

<p>3rd question: Similar issue when photographing the color squares/grid of the Colorchecker Passport. I have to take the camera off the tripod to get close enough to the passport to photograph it and in doing so, I generally have to change my shutter speed to prevent parts of the passport from blowing out when photographed using the same flash setting that will be used to photograph my subject. Is it ok that the exposure used to photograph the Colorchecker Passport is different than the final exposure of the subject?</p>

<p>Hopefully someone uses the Colorchecker Passport and outdoor flash and has some answers.</p>

[Ed_Ingold]

<p>Colorchecker Passport is designed to create a custom profile for a particular lighting condition. The analysis usually requires that areas outside the card be cropped or de-selected.</p>

<p>White/Grey cards are available in larger sizes. Most SLRs can fill the frame with an 8"x10" card. It doesn't matter if you use the white or grey side, because the camera will set the color temperature (not profile) using the correct exposure level. The grey side would be more appropriate for inclusion in one of the shots, mostly as an eyedropper point in post production. In my experience, that has limited utility, and I get better results using a calibrated monitor and my own judgement. I carry a white card, but mainly for video, which is much harder to color-correct than single images. Most concert halls and theaters use a combination of LED lights and high-efficiency replacements for incandescent bulbs. The effective color temperature is usually between 3100K and 3200K. Daylight streaming through windows and stained glass give mixed results - no easy solution.</p>

<p>A larger card won't help you with flash, because a typical flash unit is ill-equipped for what is effectively a macro photograph. When using flash as the main light, it established the color temperature of the scene. When used for fill light, check the color temperature without the flash, and filter the flash for the best blend. There's no point in having blue hightlights in a scene balanced for incandescent light. Unless you have a high-end studio flash unit, the color temperature varies with the power level. Most of the time, though, you can use one setting and handle balance in post production. It is more important to be consistent than "correct" for a string of similar shots.</p>

[digitaldog]

<blockquote>

<p>I know how to set a custom white balance in my camera but there are a couple of things I'm confused about.</p>

</blockquote>

<p>You're shooting raw or JPEG? <br>

The Passport can be used in either workflow but it's used differently. </p>

[celeste_adine]

<p>I shoot raw. Just read on the Xrite colorchecker site that you don't need to use the white card when shooting RAW, if I understand correctly. You only use that white card when shooting JPG or TIFF. A photo of the white chips included on the color grid is used to set white balance after the photos are transferred to the computer when shooting RAW and a photo of the white card is used to set white balance when JPG and TIFF photos are viewed on the computer. So maybe a custom in-camera white balance is never needed when using the colorchecker passport? Not certain I'm 100% correct though.</p>

[digitaldog]

<blockquote>

<p>I shoot raw. Just read on the Xrite colorchecker site that you don't need to use the white card when shooting RAW, if I understand correctly.</p>

</blockquote>

<p>The custom settings for the camera or any of the camera WB settings have no bearing on the raw data. But you can still use the Passport target as an aid in white balancing. It has actual neutral white patches and those that are off white in two directions of color. You don't have to use that, you can just move the raw processing WB sliders until you're happy. Or you can use the target, or a bit of both. <br>

As you capture raw, if doing so in an Adobe converter, you can also build a custom camera DNG profile which is useful. You only need a couple. You do not have to fill the frame to do any of this work however, depending on the task, more can be better. </p>

[celeste_adine]

<p>Thanks, Andrew. Your post answered some questions. After all this time worried about custom white balance only to discover it doesn't matter when shooting raw. Who knew? But I'm very happy to finally learn that :)</p>

[tudor_apmadoc]

I don't shoot with white cars any more. I use a neutral gray card - included with the color checker passport. I have the

person hold it near their face shoot one pic, then proceed.