Friday, July 27, 2012

White balance makes a big difference


"The bane of any photographer is light."

What?

"But without light we can't take pictures", you say. That is true, we need light to create our images but if you have been taking pictures long enough you know that light can be very frustrating. Too harsh, too dark, too contrasty, too this and too that. Then there is the problem of color temperature.

Incandescent, halogen and tungsten bulbs tend to be very yellow in color. Not very flattering to someone's skin tone. Fluorescent lighting tends to add green hues and now we have LED lights that are all over the color spectrum. To complicate matters even more, sometimes we have to shoot with several kinds of light all mixed together. So I say again, the bane of any photographer is light.

The solution to this is custom or preset white balance. This can either be done before shooting in camera or after shooting in post production. Which method you choose is dependent on your work habits and personal preferences. In this post I'll discuss several methods of obtaining proper white balance. Keep in mind, however, that some images will require further tweaking in post production regardless of how you set it in camera.

In Camera White Balance


There are two methods of getting proper color balance directly with your camera before you even make an exposure. They are you camera's built in white balance presets and custom created white balance.

Camera Presets


Most digital cameras come with a selection of industry standard preset white balance settings designed to correct any of the typical lighting situations a photographer encounters. This includes correcting for the common types of lights used by consumers (the masses, aka, you and I). This includes incandescent bulbs that throw off that harsh, ugly yellow light and fluorescent bulbs that can make a person looks sickly green.

Standard presets also include settings for may of the typical light situations found in nature as well. Here is a list of the typical presets found in a camera and their corresponding color temperatures.

PRESETTEMPERATURE
Daylight5000-6500 K
Shady9000-10000 K
Cloudy6500-8000 K
Incandescent2500-3500 K
Fluorescent4000-5000 K
Flash5000-5500 K


All these presets do is correct for the shift in color temperature created by these very specific lighting situations. Unfortunately they are generic settings and will get you close to a proper white balance. You need to understand that older bulbs tend to be yellower, and reflected light can have all kinds of color cast (i.e. green from grass, yellow from sand,etc.)

Custom White Balance


To really get proper white balance customized to your specific shooting situation you can take a custom white balance on site. All pro and many high end cameras allow you to create a custom color profile which the camera uses to correct for white balance. With Canon you simply take a reference exposure of a neutral gray card and select that as your source. With Nikon the process is similar except it does not store the source image, just the color data. To determine how your particular camera uses custom white balance read your instruction manual.

One trick to getting a good source shot is to set proper exposure then turn your auto focus off. A slight blur on the gray card works best. If you use something like an Expo Disc® you will need to turn AF off anyway.

Post Process White Balance


If you're in a situation where doing an in camera custom white balance is limiting (time restraints, changing variables, etc.) then this trick may best be suited for you. It requires the use of a color chart such as Datacolor's Spyder® products (SpyderCHECKR® and SpyderCUBE®) or a DIY solution like that pictured above. You simply take a photo of the chart and use that image as your basis for color correcting in a program like PhotoShop, Elements, Lightroom, Etc.

Set Your Camera


To use the chart you first have to properly set your camera's white balance. Here is the trick, if you are shooting RAW the white balance really doesn't matter too much. The camera applies the setting to the JPG preview only, not the RAW file. Your RAW processing program allows you to take the color data and apply that info during importing but it can be changed at any time in post processing. However, when we preview the image, we want to be as close to correct as possible, specially if you show your client the images. Remember the closer you get to the results you want in camera, the less you have to do in post processing.

Set your camera' s white balance to the preset closest to your shooting situation. I tend to be rather lazy about this and keep my camera set on the shade preset since I know I'll be changing it in post. While it's not appropriate for all shots it does keep the preview decent enough for most purposes. Keep this in mind if you go this route. Since this is part of my work flow it works well for me, however, it may not be the best solution for you.

Shoot the Chart


The first frame you take should be of the color chart. This will become the reference for each consecutive shot for your shoot.
If you are shooting a model, ask your model to hold the chart for you, as in the first image. If you are shooting a product, prop the chart under your lights where the product would be placed.

If you don't have a color chart you can also use a neutral gray (18% gray card) or at least something white to use as a base point. In this image I have both a color chart and a white paper sleeve the food I am shooting is placed into. (This DIY color checker is available to My Photo Group members as a download. Go to the Files section and scroll down for the file entitled ColorChecker.)

Reference the Chart in Post


When you import all your images onto your computer you can use the color information from the first frame and use it to color correct each consecutive image from that shoot with the click of a button.

Lightroom is a great tool for doing global changes over a large number of images. Once all my images have been imported into Lightroom I select my color chart image and bring it into the editing window. I then select the eyedropper tool in the 'Basic' module and click on the neutral gray square (second gray block next to the white square) and Lightroom automatically adjusts the white balance for that image. You can use any of the other squares to fine tune your images as needed.

Once the new white balance has been calibrated it can then be 'copied' and applied to any image individually or a range of images can be selected and applied globally.

Depending on what program you use the individual process may vary however the principal is the same. You are simply taking the color information from a controlled image (the chart) and applying it to each non-controlled image (the model or product).

Keep in mind that should anything changes with the lighting, you will need to take another reference shot of the color chart. This is specially true if you are shooting outdoors in natural light with changing conditions. Move your subject from under a tree to a doorway and the color cast from those two locations will have changed. Same goes for indoor shots. Move the model from the chair next to the table lamp to the bay window and the color temperature will have changed drastically.

By taking a reference shot of your color chart at the beginning of each change it then acts as a reminder that the following set of images will use a new color profile. Do this consistently and religiously and you will soon find it becomes part of your natural work flow.

1 comment:

  1. Both a large and small DIY color checker is available on the meet up site.

    ReplyDelete

Post a comment only if it adds to the topic being discussed. Spam, hate or derogatory comments will not be allowed.