Perfect Photo Color: Using a White Balance Cap
Achieving Accurate Color Balance in Photography
Digital cameras generally offer an automatic white balance feature. However, this automated system often provides results that are nearly correct, but lack absolute precision.
This article details how to utilize a white balance cap – whether purchased or created at home – to attain optimally balanced colors in your photographs.
Understanding White Balance
Proper white balance ensures that white objects appear white in your images, and all other colors are rendered accurately. Incorrect white balance can result in color casts, such as images appearing too blue or too yellow.
While automatic white balance is convenient, it can be fooled by unusual lighting conditions. A white balance cap offers a reliable reference point for the camera’s metering system.
Using a White Balance Cap
A white balance cap is a specially designed accessory used to calibrate your camera’s white balance settings. It provides a neutral gray surface for the camera to read.
The process involves the following steps:
- Place the cap in front of your lens, ensuring it fills the frame.
- Set your camera to custom white balance mode.
- Follow your camera’s instructions to take a reading from the cap.
Commercial vs. DIY White Balance Caps
Commercial white balance caps are readily available for purchase and are typically made from a precisely calibrated material. They offer consistent and reliable results.
Alternatively, a DIY white balance cap can be created using a piece of neutral gray cardstock or foam board. While less precise than a commercial cap, a DIY option can be effective in many situations.
Benefits of Using a White Balance Cap
Employing a white balance cap yields several advantages:
- Improved Color Accuracy: Ensures true-to-life colors in your photographs.
- Consistency: Provides repeatable results, especially in challenging lighting.
- Reduced Post-Processing: Minimizes the need for extensive color correction in editing software.
By taking the time to calibrate your camera’s white balance with a cap, you can significantly enhance the quality and accuracy of your images.
What is a White Balance Cap and Why Use One?
Numerous methods exist for establishing white balance within your camera, with subsequent adjustments possible during post-processing. The most straightforward approach, though often unreliable, involves allowing the camera to automatically determine the white balance.
However, automatic white balance frequently results in inaccuracies. While contemporary digital cameras represent remarkable technological achievements, employing sophisticated algorithms for tasks like image compression and exposure, achieving accurate white balance remains challenging.
Instead of relying on automatic settings, manual white balance adjustment is possible. This can be done through preset options within the camera, tailored to various lighting scenarios, or by creating a custom preset utilizing a gray card. Preset options depend on the camera manufacturer’s interpretation of lighting conditions, which may not reflect the actual environment.
Creating a custom preset with a gray card requires time and effort – extracting the card, capturing a reference image, and then storing it away. Alternatively, incorporating a white card into initial shots allows for its use as a reference during post-processing to establish a white balance value for subsequent images captured under similar conditions.
This latter method, while effective, is both time-consuming and potentially costly, as basic photo editing software often lacks the necessary functionality for applying a custom white balance across an entire image set. Furthermore, even slight changes in the angle at which the white card is photographed can significantly alter the resulting values.
Given the limitations of automatic settings, presets, and gray/white card methods, what alternatives are available?
The solution lies in utilizing white balance caps. When employed correctly, these caps offer the simplest and most reliable means of achieving consistent, in-camera white balance and color correction. A white balance cap functions as a lens cover, incorporating a semi-translucent material that serves as a neutral color reference for the camera.
Technically, a well-designed white balance cap permits light transmission to the camera’s sensor, effectively recreating a neutral 18% gray – mirroring the function of traditional 18% gray reference cards. The image shown is a photograph taken through the cap after in-camera calibration, demonstrating the even and neutral gray light achieved.
The cap’s effectiveness stems from its ability to transform the camera into an incident meter. Instead of measuring light reflected *from* the subject, as with automatic white balance and white card referencing, it measures light falling *onto* the subject, determining the light’s temperature directly.
Understanding Commercial and DIY White Balance Caps
White balance caps present an appealing solution for achieving accurate color in photography, but are they worth the investment? A key consideration is the cost, which can be surprisingly high for a seemingly simple device – a lens cap containing a piece of plastic.
The premier white balance cap available is the Expodisc, with prices ranging from approximately $70 to $120 depending on size and model. More affordable alternatives, such as the Promaster cap, are available for around $10 to $15. A cost-effective option is the DIY approach, utilizing two UV filters and readily available filler material; two standard UV filters typically cost around $10.
To determine the optimal recommendation, we conducted a comparative analysis. We assessed in-camera automatic white balance alongside the calibration provided by the Expodisc, a Promaster cap, and a custom-built DIY white balance cap, all under identical conditions and across diverse shooting environments.
What specific benefits does each price point offer? Let's examine the specifications of each type of white balance cap in detail.
Expodisc: Construction and Features
The Expodisc boasts a robust construction, utilizing machined aluminum. Its mounting system is exceptionally user-friendly, featuring spring-loaded bearings on the cap’s rim. This allows for quick attachment and removal without the need for threading or latches.
The diffusion material is multi-layered, incorporating several semi-opaque plastic layers topped with a plastic diffuser similar to those found in shop lights. A lanyard attachment point is integrated into the main ring. The entire unit is hand-assembled and calibrated in California, with a calibration/test card included. While a premium price is attached, the Expodisc is a durable and well-engineered device.
Notably, it is the only white balance cap that undergoes laboratory testing and certification to meet specific light transmission standards.
Promaster Cap: Design and Durability
The Promaster cap is constructed entirely of plastic and features a single layer of light diffusion material embedded within a standard lens cap that secures with tension clips. The plastic is relatively thin, allowing some visibility through it, indicating less than complete light diffusion.
It doesn’t feel particularly robust and may be susceptible to damage with rough handling. However, its lower cost allows for the purchase of multiple units for the price of a single Expodisc.
DIY Cap: Sturdiness and Materials
The DIY cap offers considerable sturdiness, being built from two aluminum filter rings and their accompanying UV glass. Significant force or direct impact would likely be required to cause damage. The diffusion material, as explained below, is determined by the material placed between the two filter glass layers.
Before examining sample photos, let’s explore the construction of the DIY filter.
Constructing the DIY White Balance Cap
Creating a DIY cap is a straightforward process. You could even test materials by simply holding them in front of the lens, a useful step before committing to a permanent build. All that’s required are two identical UV filters, sized to fit your camera lens’s thread mount.
For our test setup, we utilized two 52mm Tiffen brand UV filters. To transform these filters into a white balance cap, a filler material is needed. Numerous online tutorials suggest options ranging from white coffee filter paper to tissue paper and dust mask filters. Given the low cost of materials, experimentation is highly encouraged.
To assemble the DIY cap, place one UV filter onto your chosen material, trace its outline with a pencil, and then cut out the shape, slightly smaller than the traced line (as the inner diameter of the UV filter is smaller). Then, sandwich the cut disc between the two filters and screw them together.
This completes the DIY cap assembly. While not complex, selecting the appropriate filler material presents a challenge. In our testing, coffee filter paper produced a warm tone, tissue paper a cool tone, and the filter material from a white dust mask (available at hardware stores) came closest to neutral, with a slight coolness. We didn’t find a material we were entirely satisfied with, so we used the dust mask material for demonstration purposes, as it’s a commonly recommended option.
Now that we’ve reviewed the pricing and construction of each white balance cap, let’s examine how to use one and analyze the results.
Understanding and Utilizing a White Balance Cap
As previously discussed, a white balance cap transforms your camera into an incident light meter. This allows for measurement of light falling on your subject, rather than light reflected by it. Consequently, you can calibrate your camera to the actual light temperature, avoiding inaccuracies caused by subject and environmental reflections.
To effectively utilize this capability, position the camera at the subject’s location and direct it towards the intended shooting position. For example, if photographing an athlete near a goalpost from the 20-yard line, move to the athlete’s position and meter the light from your photographic vantage point.
Camera operation varies by model, so consult your user manual. Typically, navigate to the camera settings, locate the white balance options, and select ‘custom white balance’ instead of ‘automatic’ or a preset like ‘incandescent’. Attach the white balance cap, aim towards your light source, and capture a reference image.
This reference image informs the camera about neutral color under the specific lighting conditions. It establishes a baseline for accurate color rendition.
The Impact of Custom White Balance
What is the visible difference between relying on automatic white balance and employing a custom setting with a white balance cap? Consider the following image of a standard Stop sign:
These photographs were taken during a late evening under overcast skies, where the natural light exhibited a warm tone. The image on the left utilizes the camera’s in-camera white balance. Notice the blue tint on the sign and the somewhat sterile appearance of the foliage.
After utilizing the Expodisc and obtaining a white balance reading, the second image was captured. Colors are demonstrably more accurate, and the sterile blue cast is eliminated, better reflecting the scene’s true appearance.
Now that we’ve established the function of the white balance cap, let’s compare the performance of different caps under varying lighting scenarios. As in previous tests, our action figure, Spawn, will assist in this evaluation.
The following images were captured on a sunny day, with the subject positioned in the shade of a tree against a white building:
Under these conditions, automatic white balance produced a slightly cool result, while the Promaster cap yielded an excessively cold tone. The DIYdisc offered only a marginal improvement over the camera’s automatic setting.
The Expodisc consistently delivered the most accurate color reproduction in this test, effectively warming the image.
Let’s examine another test, featuring a lily against a backdrop of green foliage and a white wall:
Similar to the previous example, automatic white balance and the DIYdisc produced comparable cool tones. However, the Promaster performed significantly better in this scenario, closely approximating the warm tones achieved with the Expodisc.
A pattern of inconsistency is becoming apparent, linked to the thickness and quality of the filter material. The DIYdisc utilizes a thick filter, and the Expodisc incorporates multiple layers of plastic. Conversely, the Promaster is remarkably thin.
This thinness allows some light transmission, potentially compromising the accuracy of the neutral color metering process. The Promaster may not provide a consistently reliable reading due to this light leakage.
Final Assessment
Numerous DIY Expodisc guides are readily available online, and a common thread among them is criticism directed towards the Expodisc manufacturer. Many claim the product is an excessively priced item easily replicated. While this assessment may be somewhat severe, it holds a degree of truth. Constructing a functional Expodisc alternative is certainly achievable, but it necessitates a process of experimentation and refinement.
If cost savings, camera experimentation, and the satisfaction of a DIY project appeal to you, building your own Expodisc is a viable option. However, anticipate needing to test various materials before achieving satisfactory and consistently high-quality outcomes. Our own experience involved evaluating nearly a dozen different materials before reaching even a preliminary level of satisfaction.
Furthermore, suggestions of using items like fast food napkins or Pringle can lids for white balance readings are, in our opinion, impractical and unreliable.
Our evaluation of the Expodisc reveals it to be a robust and thoughtfully designed tool. Across a diverse range of subjects – including flowers, figurines, portraits, architecture, landscapes, and artwork – it consistently delivered reliable results.
Each photograph taken after camera calibration with the Expodisc exhibited a neutral color profile, with a subtle warmth that proved aesthetically pleasing for both landscapes and portraits. This level of consistency surpassed the performance of the camera’s automatic white balance, our homemade version, and the Promaster alternative.
Therefore, the key takeaway is this: for those prioritizing speed and dependable results, particularly when inconsistent white balance would necessitate extensive post-processing work in applications like Photoshop, the Expodisc represents a worthwhile investment.