Capture

Capture overview

Capture is the start phase of your workflow. How you capture digital images depends on many things, which we summarize in Best Practices>Camera, and more specifically in the Shoot Objectives section and RAW vs. Rendered sections. The capture workflow items to address are how you set up the camera, and they are largely based on whether you using a raw workflow, a JPEG workflow, or whether you are depending on the camera to provide a completely in-camera JPEG batch workflow.

Camera setup for raw capture

Since raw capture files allow all parameters to be adjusted in PIEware, camera settings are easily changed (other than exposure, shutter speed and lens aperture). However, workflow efficiency can be improved in some situations by use of custom white balance and/or the inclusion of a white balance reference such as a WhiBal card or an X-Rite ColorChecker

Recommendation

Although a prime advantage of raw capture is the ability to fine-tune white balance in PIEware, there are times when it makes smart workflow sense to create and use a custom in-camera white balance. One example is a portrait series where a person in a red shirt is followed by one in a green shirt. In this situation, the white balance will change and will affect skin tone.

The goal is to keep the tone neutral and avoid adjusting each subject's set of images. The solution is to generate a custom in-camera white balance for the lighting set-up using a white card as the target. Now we can do 20 portraits and get the same consistent skin tone or background color. If a color temperature tweak in PIEware is needed, one global shift is all that is necessary. Using this technique will usually position the frames within +- 50K of perfect white balance and tint.

Whether lit or available light, we always use this technique for portrait shoots- whether lit or available light- since it simplifies optimization, even for raw files. It is also great for shooting under fluorescent light since auto white balance can shift a lot. Remember, it's easier to make one global correction later during optimization. In situations where the background and lighting change, it is often easier to simply include a reference grey card then correct the white balance in PIEware for each lighting setup. It can be tricky to figure out the ideal placement for a reference card in situations other than a controlled lighting setup. Try to put the reference card somewhere central in the image in the dominant light temperature, and try to avoid glare on the card.

Although most cameras only offer full resolution file sizes for raw capture, a few cameras offer lower resolution raw file capture as well. The main selling point of offering low and medium resolution raw files is to reduce storage overhead for situations when raw adjustability is desirable, but final output needs are less than the full size the sensor is capable of. For a comparison of file size and storage requirements, Canon has provided the chart below for two of their current cameras that have this feature.

Figure 1 Canon’s comparison of file size and storage requirements.

The only other in-camera setting that you may consider for raw capture is sharpening. Once again, any in-camera sharpening setting is not applied to the raw files, but it is applied to the JPEG preview. This preview is the image that appears on the camera LCD, and as a proxy image in browsers that don't create their own JPEG preview from the raw data.

Since cameras vary in the relative softness of unsharpened files, some prefer to leave the default sharpening setting when shooting raw hence the preview image is easier to evaluate for focus on the camera LCD. Whether this makes any real difference for you depends on the camera model and whether you use the LCD to evaluate images for focus. We find the default settings to be useful for most for the DSLR cameras we've tested.

Although they are recognized by manufacturer's raw conversion software as starting points for image adjustment, in-camera settings for picture "looks" (tone, contrast, saturation) are ultimately irrelevant for raw capture. Adobe has recently replicated many of these picture "looks" as starting point "profiles" in ACR and Lightroom, but unlike manufacturer's software, Adobe software does not read these settings from the raw file and apply them automatically as the manufacturer's software does.

Other browsers, such as PhotoMechanic, can read the embedded JPEG profile (reflecting the in-camera "look" setting) or can optionally use the system to render the raw file creating a new JPEG preview, which will not reflect the in-camera "look" setting.

Another in-camera setting you can largely ignore is capture color space. A raw file is not encoded with a color space. The raw file has data that describes the full gamut capability of the sensor and is not encoded with a color space (profile) until it is exported from the raw processing software as a rendered file.

Different raw processors offer different choices of output color space, but the most commonly used ones are sRGB, Adobe RGB (1998), and ProPhoto RGB. Only the ProPhoto RGB space can contain the full gamut of the camera sensor.

Camera setup for JPEG capture

For many point-and-shoot cameras, JPEG capture is the only option. Some medium-format backs shoot only raw, while others can shoot JPEGs and raw + JPEG. Most DSLR cameras shoot raw, JPEG, or raw + JPEG.

The essential feature of JPEG capture is that the camera shoots a raw file and applies camera settings. The raw file is then processed out to a JPEG and the original raw data is deleted. As the raw data is processed, it ends up in a user determined color space, such as narrow gamut sRGB or wider gamut Adobe RGB (1998). Both of these color spaces will be smaller than the gamut potential of the sensor.

Cameras that shoot JPEG generally have size and/or quality options. Size refers to the pixel dimensions (resolution) of the captured file, and quality refers to the amount of compression applied to the saved JPEG. Most of the time, there is no good reason to shoot at less than the maximum image size. The case for shooting at the highest possible JPEG quality (least compression) is not as clear-cut. Increasing JPEG compression will result in more compression artifacts, and these artifacts will become more visible as the compression levels increase. Depending on the camera, there may be only three, poorly defined quality levels available: fine, normal, and low. If this is the case, it is always best to choose “Fine.” More sophisticated cameras may offer a sliding scale (1-10) for example. Unfortunately, there is no defined standard for these sliding scales.

If you wish to test JPEG files for artifacts at different quality settings, the best method is to shoot something with hard edges (like a building) and look carefully in the red channel for artifacts.

Color balance is determined by the camera setting. Although some adjustment can be made to the white balance of the JPEG file, it has to be done with 8-bit data, and this is destructive to the image data. Auto white balance works reasonably well in most "normal" lighting, but is thrown off by mixed lighting, or difficult light sources such as fluorescent and tungsten. JPEG shooters will get better white balance by choosing one of the white balance presets, such as daylight, cloudy, shade, fluorescent, tungsten, etc.

	AWB: Similar to scene averaged metering, when using Auto White Balance, the camera determines the correct white balance based on evaluation of the scene. The camera usually bases its evaluation on the brightest light source.
	Daylight: The daylight setting is based on the average color temperature of bright noontime sunlight with no cloud cover, around 5600˚K. Be aware that the temperature of actual daylight varies greatly throughout the day.
	Tungsten/Incandescent: On most cameras, the incandescent setting is based on the color temperature of a household incandescent light bulb, 2500-2800˚K. This setting is usually not for professional quartz-halogen lights, which are typically 3200˚K.
	Fluorescent: The fluorescent setting corrects for the greenish hue produced by most commercial fluorescent tubes. This setting usually expects daylight balanced tubes, so it may not work when shooting with compact fluorescent bulbs.
	Shade: The shade setting tries to counteract the blue bias of daytime shade. Often this setting results in images that are too yellow.
	Cloudy/Overcast: The cloudy/overcast preset is slightly cooler than the shade preset, also correcting for the blue bias on overcast days.
	Flash: Flash is very close to the daylight setting but is slightly bluer, around 6000˚K.
	Custom: Most DSLRs include at least one custom white balance setting that is set by shooting a white card under your designed lighting conditions.
Figure 2 White balance settings

Some cameras also allow the user to set a specific color temperature in degrees K. This can be useful when shooting in conditions where the color of the source is known, but it is impractical to shoot a white card, such as when shooting theater performances. It can also be used to cheat the color of a scene either warmer or cooler.

Even more control of in-camera white balance can be achieved by using a white or spectrally neutral grey white balance tool. These tools come in the form of disks, targets and cards. Disks are diffusion devices that fit over the front of the lens, while targets and cards are meant to be photographed and the resulting image used for a custom white balance setting. One example of an easy to use target is this one http://www.balancesmarter.com/

Another setting important for JPEG capture is choice of color space profile. Most DSLR cameras have a choice of sRGB or Adobe RGB (1998) for the color space of the JPEG capture files. sRGB is a small consumer oriented space originally designed for use on monitors, consumer printers, and the Internet. Since it has a relatively small color gamut, it is not as susceptible to color shifts due to un-calibrated and un-profiled monitors and other devices.

Many commercial digital printers use this color space by default to avoid print matching issues. The wider gamut Adobe RGB (1998) color space is more appropriate for commercial print and inkjet printing. Although Adobe RGB is an improvement gamut wise over sRGB, it doesn't capture the full gamut the sensor can detect.

A color space like ProPhoto RGB would encompass most of the sensor gamut, but is not offered as an in-camera color space choice, which is yet another reason to choose a raw workflow over a JPEG workflow if commercial print or inkjet output is where your pictures are headed.

Camera setup for in-camera JPEG batch workflow

Although not a dpBestflow recommended workflow, we are aware of some circumstances that make sense for a completely in-camera JPEG batch workflow. One that we know of is sporting event coverage. Sports shooters often are on the road covering events with the expectation that their photos need to be published online within hours if not minutes of the end of events. Sometimes the only realistic way to accomplish this is to use camera settings that will provide a reasonably finished JPEG file that can be used right out of the camera without additional post processing. In this case, choosing a good white balance, picture "look" and sharpening is essential. Testing these parameters and getting to know what your camera delivers at each of these settings are essential to this workflow.

We understand why someone might gravitate to this workflow, but we don't think it is actually necessary if you have access to a fast laptop and an all-in-one application like Lightroom or Aperture.

These applications can quickly apply post production tweaks to JPEG files such as white balance, tone, saturation, and sharpening, allowing you to apply neutral settings to your JPEG captures-preserving your ability to make higher quality renditions of these files at a later time.

We particularly don't like the thought of using this workflow for "important" news coverage. We suggest that these shooters at least shoot raw + JPEG so that there is a raw file to go to for those images that become iconic records of events.