Why does auto white balance change from shot to shot during a portrait or still-life session?

Asked 8/8/2020

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I’m shooting portraits and still life on a Nikon D780 in JPEG with Auto White Balance. During a session, the color sometimes shifts from cooler to warmer between frames, even when I use the same setup. It happens with both flash and natural light, and with different lenses. Can something in the scene be confusing AWB, and how can I keep the color more consistent?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

5y ago

2 Answers

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Ahhh...the "curse" of auto-white balance. I don't use AWB and ... based on reading, it seems like few photographers suggest using this feature.

You did not mention a camera brand-model ... but that information would likely not change the response.

If you shoot 'RAW' (which preserves the maximum amount of data and post-processing adjustment latitude) then White Balance (for most cameras) is 'recorded' in the meta-data, but not actually applied to the image data. This means that if the camera got it wrong, you can fix it.

If you shoot JPEG, the White Balance is applied to the image (and you lose color-depth information... JPEG is 8-bit data whereas most cameras use 14-bit RAW data).

Optimal White Balance techniques rely on a 'known' neutral source (it need not be white and is usually a neutral gray). Auto White Balance doesn't have the advantage of a 'known' color-neutral target and tries to guess (for better or worse) -- so you're playing the odds when you use Auto White Balance ... and it often disappoints. The main point is ... you don't get to control the results (which puts you at a major disadvantage.)

I am not aware of any cure-all for White Balance reliability issues.

When color accuracy is important (it is not always important ... more on that later), use a neutral gray card to establish white balance.

I say "not always" because some photography would be ruined by accurate color balance. e.g. Sunset photography means blue light is absorbed by particles in the atmosphere and you get a preponderance of gold/orange/red (longer wavelengths wrap around the particles instead of being absorbed)... use of neutral gray cards to neutralize this color offset would probably ruin the artistic value of the shot.

Originally by user82237. Source · Licensed CC BY-SA 4.0

user82237

5y ago

0

AI Answer

Generated from our catalog & community — verify before relying on it.

Yes. Auto white balance is only an estimate, so it can change from shot to shot as the camera sees different parts of the scene. Strong dominant colors in the subject or background can influence that estimate, making one frame look cooler and the next warmer.

Lighting can also cause it. Some lights do not produce a perfectly constant spectrum, so color can vary during the light’s cycle even if your eyes do not notice it. If flash is the main light, AWB may also be less reliable because the camera does not fully evaluate the flash color before the exposure; using a dedicated Flash white balance setting is often more consistent.

For the most consistent results, don’t use AWB for controlled portrait or still-life work. Set a fixed white balance, use flash WB when flash is dominant, or set a custom white balance from a neutral target. Shooting RAW also helps because white balance is stored as metadata and can be corrected later much more easily than with JPEG.

UniqueBot

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5y ago

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