Camera & Craft

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Chapter Five: Light Becomes the Image

Painted Light Portrait—A Long-Exposure Test

Part of being a successful photographer is knowing your gear, which—for this chapter—means knowing how far you can push your camera’s sensor. In this exercise, you’re going to test your sensor by working it hard, intentionally heating it up to create some serious noise. This is a long one, so read it through to the end before getting started.

    Camera Gear: Camera, wide-angle lens, tripod, cable release (optional), handheld light meter (optional) and a gray card

    Extra Gear: Flashlights

    Other Stuff You’ll Need: Friend(s) to pose

    Your Goal

    The goal is to find out about your camera’s noise level at a low ISO with a long exposure time—and at a high ISO with a shorter exposure time. At low ISOs, there’s less noise from the signal being amplified, but there might be increased noise from heat and random photons. At high ISOs, you reduce the heat from the CMOS sensor being on, but increase the noise from amplifying the signal.

    You’re going to capture some deep shadows, and by looking into those tones, you’ll perform a subjective noise test. When you finish, you’ll be able to decide whether it’s better to shoot at fast shutter speeds at high ISOs—or at long shutter speeds at low ISOs.

    Location Scout

    Go exploring outside in daylight to find an interesting location: You’ll be returning to it for a night shoot. It’s fine if there are streetlights or other ambient light sources, as long as there will be a range of dark tones and shadows at the scene. Figure out your shot now, so you won’t have to scout around in the dark during the actual shoot.

    Shoot Night

    Pack up your friend, flashlights and camera gear and head out to the location you scouted earlier. Put your camera on the tripod and frame up your shot.

    Aim for these elements while framing:

    • Deep backgrounds—Avoid putting your subject in front of white walls; you want dark areas behind them.
    • Use a wide-angle lens—Give yourself enough room to work by having plenty of space around your subject.

    Painted with Light

    The creative goal for this exercise is to paint with light. Different flashlights and techniques will offer different qualities, so explore tungsten, LEDs and other lights sources.

    Here are a few starting points:

    • If you point the flashlight at the camera, you’ll create floating streaks of light.
    • If you point the flashlight at your subject, you’ll illuminate them — and not yourself or your flashlight, as long as you hide the bright end of the flashlight from the camera.
    • You can outline things, write words, or sketch shapes with the light.
    • Attach a flashlight to a string and spin it around to create patterns.
    • Attach lights to your body and move through the scene.

    Exposure

    This isn’t an exact science; there’s plenty of latitude for error in exposure.

    With flashlights as your light-source, there are a few factors to work with:

    • Power of the flashlight: i.e., how bright is it?
    • Beam angle: Is it a laser pointer or a floodlight? Are you using a fine-point brush or a giant bucket?
    • Time of exposure: The longer you keep the light on an area, the brighter it will be.
    • Movement and Time: This is a big variable. If you leave the flashlight in one place, its exposure accumulates. Quick moves give you less exposure—slow moves give you more.
    • Distance of the flashlight: By increasing the distance from your subject, you decrease the power of the flashlight, and vice versa.
    • Direction of the flashlight: Pointed directly at the lens, a flashlight is a very bright object. Pointed at your subject, the brightness will depend on reflectivity—and the other factors listed above.

    Series One—Low ISO for 30 Seconds

    For the first series of images, set your camera to its lowest normal ISO (usually ISO 100). Choose 30 seconds as your shutter speed, and start with a middle aperture (ƒ/8).

    Frame up the shot with your camera on a tripod:

    1. Decide on a style and pattern of light painting.
    2. Take your first image. Come back and check out your results, evaluating your technique and exposure. Vary your aperture as needed to balance out the exposure.
    3. Take a second image. Review and adjust again. Repeat until you feel that you have a good aperture value and a good method.
    4. Take a series of ten images.

    Series Two—High ISO for 10 Seconds

    For this series, set your camera to a high ISO. Use at least ISO 800 (older cameras) or ISO 1600 (newer cameras), since these are considered to be good quality, high ISO settings. Choose ten seconds as your shutter speed and start with a middle aperture (ƒ/8).

    Frame up the shot with your camera on a tripod:

    1. Continue with your style and pattern of light painting.
    2. Take your first image. Remember that you only have ten seconds to work with this time, so speed up your pattern. Come back and check out your results, evaluating your technique and exposure. Vary your aperture as needed to balance out the exposure.
    3. Repeat until you feel that you have a good aperture value.
    4. Take a series of ten images.

    Series Three—Extreme ISO for 1 Second

    For the last series, set your camera to an extreme ISO, whichever one pushes your camera right up to the limit of its abilities. Choose one second as your shutter speed, and start with a deep aperture (ƒ/22).

    Again, frame up the shot with your camera on a tripod:

    1. Continue with your style and pattern of light painting.
    2. Take your first image. Remember that you only have one second to work with this time, so you’ll need to move very fast. Evaluate your technique and exposure. Vary your aperture as needed to balance out the exposure.
    3. Repeat until you feel that you have a good aperture value.
    4. Take a series of ten images.

    Back at Your Digital Darkroom: Noise Evaluation

    Download your images and open them in your raw processing application. Find the best single image for each series and repeat the following process with all three images. We’re going to use Lightroom for our examples, but the toolsets are similar in most raw processing applications.

    Find the noise:

    In LR, bring up the Develop module, leaving the settings at their default values. Find the Noise Reduction tools; in LR they’re located in the Detail panel. Find the darkest part of the image that still has some tone. Use 100 percent pixel view so that you see an accurate rendering of the noise.

    Look for:

    • Luminance noise: Granular patterns of specks and unwanted textures
    • Chroma noise: Splotches of green/magenta
    • Patterns or Banding: Any repeated patterns of lines or shapes that are artificial
    • Hot Pixels: Bright single pixels that are either white or a single color

    Adjust Luminance noise:

    The goal is to remove unwanted texture, but leave enough so the image doesn’t look plastic or have smeary pixels. We find that our settings for this run between a value of 8 for low-ISO images and 35 for high-ISO images. Push the slider too far so you can back off from a bad adjustment, until you get to a point where you’re satisfied. Then use the On/Off technique. The Detail and Contrast sliders are there to help you retain important detail. Think of them as adjustable limiters that tell the Luminance tool what to pay attention to and what to ignore.

    Tip: In Lightroom, if you hold the Option key while using the Detail and Contrast sliders, you’ll see a gray scale image that shows you exactly what’s being affected by the tools.

    Adjust Color noise

    Here, you want to remove those splotches of green/magenta color. We find our general low-ISO setting to be about 10 and our high-ISO settings to be 50–60. Push the setting too far, and back off, while observing the noise and fine detail. Adjust the Detail slider to limit what the Chroma tool affects. Adjust the Smoothness slider; after the Color slider takes out the primary chroma noise, this slider takes another pass at the noise, removing a subtler, lower-frequency pattern.

    Adjust Sharpness

    The Sharpening control affects texture and detail; often, luminance and color noise affect those areas as well. Once we’ve adjusted the Noise Reduction tools, we like to go back to sharpening, and then examine the adjustments. Often, small changes to this panel can improve the fine detail that may have been damaged by the Noise Reduction tools.

    Repeat and Compare

    Go through this process with your three selected images. Zoom each one to 1:1 Pixel View, and examine similar areas in each one. The goal of this process is to gain insight into the choices you can make when setting up your camera for low-light situations.

    Insights

    • Which image looks best without noise reduction?
    • Which image looks best with noise reduction?
    • Which image has the best looking fine detail?
    • Which image is best overall?
    • What tradeoffs do you make when choosing a faster shutter speed and a high ISO?
    • In which situations would extreme ISO make sense?
    • What tradeoffs do you make when choosing a low ISO and a slow shutter?
    • In which situations would it make more sense to choose a low ISO?