Setting the Exposure on Your Digital SLR Camera Manually - dummies

Setting the Exposure on Your Digital SLR Camera Manually

By Robert Correll

You can effectively troubleshoot exposure by bypassing the digital SLR camera’s autoexposure modes and handling it yourself. Remember that one of the most powerful exposure tools in your arsenal is you.

Each photographic stop has the same effect on exposure, whether it comes from shutter speed, aperture, or ISO. You can swap one for another to get to the exposure you need.

Here are some suggested steps to setting exposure manually:

  1. Select your camera’s manual mode.
  2. Decide what exposure control you want to set first.
    Let your creative goals guide you to limit one of the three exposure controls:
    • Aperture: Smaller is better for landscapes. Larger is better for portraits.
    • Shutter speed: Set a fast minimum (this is the point you’re not willing to shoot slower than) for action and dim light when going handheld. If you try another mode first and the shutter speed is too low, switch to shutter-priority mode. Set the shutter speed high enough to avoid blurring.
    • ISO: For shooting still subjects from a tripod, set to lowest ISO and slow shutter speed. If your camera shoots relatively noise-free photos up to ISO 800, use anything from ISO 100 to ISO 800.
  3. Set the first value.
    Typically, this will be aperture or shutter speed. Setting the aperture guarantees you the depth of field you want. Setting the shutter speed helps you capture action or prevent yourself from taking blurry photos.
  4. Set the second exposure control.
    Quite often, you may have set the aperture first but now bring in shutter speed to guarantee a crisp photo. You may want to set the ISO sensitivity now to keep noise to a minimum.
  5. Adjust the third exposure control to get the right exposure.
    This is what I call the “floating” control. It has to be able to move around so that you can set the exposure. The exposure scale tells you whether the camera thinks you’re under- or overexposing the photo, or right on the mark. When you’re troubleshooting, you may need to ignore the camera meter. If you’ve already taken a shot and it was too bright, tone down the exposure by a third, a half, or a whole stop. Raise the exposure if the photo was too dark.

    Don’t make wild changes unless the other photos were significantly off, too. Keep changes small and try to be methodical about it.

  6. Take a photo.
  7. Review it.

    This is the most important step.

    • Look at the photo on your monitor and decide if it appears underexposed (too dark) or overexposed (too light). Be aware that your perception may be affected if you’re looking at the photo in extreme conditions (bright or dim), or if you’ve altered the brightness level of your LCD monitor. The histogram is helpful in these situations.
    • Check the color histograms to see if any colors are clipping.
    • Zoom in, if necessary, to check details. If the exposure looks good, this photo is in the bank. You may be able to use the same settings for more photos, provided the scene and lighting don’t change much.
  8. Continue adjustments, if necessary.
    If the exposure is off, return to Step 5 and work with your floating exposure control. You may also return to Step 4 and revise the second control. If your exposure solution won’t work for more drastic reasons ― you can’t set the right shutter speed to avoid blurring or you’re concerned about too high an ISO, go back to Step 2 and reset your priorities. You may have to live with more noise or a shallower depth of field.
Setting manual exposure for a properly exposed photo.

Shutter speed is generally the least forgiving exposure element. It’s easier to accept different depths of field or noise levels, but camera shake and motion blur caused by slow shutter speeds provide little artistic leeway.