Auto White Balance, a Cautionary Tale

Author: Ken Brown

AWB is a pretty neat (I am trying to avoid color temperature terms like “cool”) concept.  Set it and forget it.  Right ??  WRONG !!  I should start by saying that if you shoot in RAW, you are somewhat immune to this issue, as you can always adjust the color temperature in PS or LR.  However, even if you are shooting in RAW, don’t you want to try and get as close to the desired image right out of the camera? Of course you do, and there are other reasons to at least use a Camera Preset WB – one of those little images that you can dial in (a cloud, or a flash, or a tungsten light, etc.)

Reasons to use a Preset EVEN IF you are shooting in RAW:

  1. If you are shooting all day. Why would you want to make so many color temperature adjustments when post processing your images?
  2.  If you are taking multiple images and stitching them together for a panorama. You do not want different color temperatures in the different shots you’re blending, and with non-uniform lighting conditions, that can definitely occur.

But the major reason NOT to use AWB is, if you are shooting in JPEG or using the JPEG processed image, certain conditions can lead to poor results.  The camera tries to apply the right adjustment, but it simply cannot, or overcompensates due to the conditions.

What follows is a great example to convince you…  The photo is not great, but you can see what I was trying to do, shoot a hay bale in the background, framed by an old trellis leaning up against a tree in the foreground.  I won’t tell you what camera I shoot with, as I don’t want to turn this into a comparison of AWB between different cameras (although I’m guessing that there are some differences there as well).  I will tell you that this was shot with a pretty high end body and excellent lens – that is not the issue. The issue is the limitation of AWB, and that the camera is trying, really, really hard to assess the condition of the light and automatically apply the right electronic signal to the image sensor data and achieve an accurate color.  In this example, and in many other cases where you don’t have great lighting, it really missed the mark.

Shooting conditions – Heavy overcast sky

Camera Settings – ISO 4,000, f/13, 1/80 sec, 100mm telephoto

1 - The camera set on full AWB, shot in RAW, but opened as a JPEG.

1 – The camera set on full AWB, shot in RAW, but opened as a JPEG.

You can see that in the first image (full AWB), the camera adjusted and created a much “cooler” image (now I’m talking color temperature).  The whites have taken on a blue tone – the camera has added blue based on its interpretation of the lighting conditions.

2 - The camera set with the "Cloudy" Preset for WB, shot in RAW, but opened as a JPEG

2 – The camera set with the “Cloudy” Preset for WB, shot in RAW, but opened as a JPEG

The image with the camera using the “cloudy” preset has the correct, warmer tones, even just opened in JPEG with no adjustments to the RAW image.

3 - The first image (full AWB), but this time opened in RAW with the WB adjusted in Photoshop and saved as a JPEG

3 – The first image (full AWB), but this time opened in RAW with the WB adjusted in Photoshop and saved as a JPEG

For the third image, I opened the first one (with full AWB) in RAW, but adjusted the color temperature to roughly equal the cloudy preset.

If there had been snow on the ground (there was a few days ago in Vermont) the full AWB would have been much, much worse, and given all the snow a blue color as well.  Maybe you have shot images like this on a cloudy/overcast snowy day with your camera on AWB.

So to conclude…  Yes – You can use AWB and make an adjustment to the RAW image to “fix” the color.  But 1) If you shoot in JPEG or just open your images in JPEG this won’t help you.  Even if you shoot in RAW and open and adjust the color temp, why do this if you don’t have to.  As mentioned earlier, even this might cause you a problem under certain shooting conditions.

At least use a preset – they were put on your camera for a really good reason, and they are easy to use.  Many cameras allow a much more precise setting of color temperature, either to dial in the specific Kelvin Temp, or to create a preset for your images using the actual ambient conditions.

This  latter approach works really well for example inside dimly lit halls, like a church with really warm (temperature) lights.  Each camera manufacturer has a different approach to creating this type of preset.  But if you are going to do a lot of indoor photography of this type, I highly recommend learning this.  It’s generally very simple once you know how.  For my camera, I click the preset WB setting, take a shot of what “should be white” in the image, and White Balance is set.  Now I can get really accurate color, REALLY important with people in the image.

Happy shooting, and hopefully I’ve convinced you to at least use one of your camera presets.

 

Ken Brown is a Trip Leader with Arizona Highways Photo Workshops

 

 

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