How Your Camera Meters Light
Your camera reads the light in your frame with several different methods. I recommend using the Evaluative method (Canon) or Matrix Metering (Nikon). All cameras will have a similar method - look for the symbol that looks like an eye in a rectangle.
Evaluative metering reads the entire scene to evaluate the best exposure overall but puts most importance where your light meter is pointed. The light meter is tied to the focus point in either live view or looking through the camera.
The 18% Gray Reality
Your camera is calibrated to assume the average brightness of your composition equals 128 (middle gray). In a scene that's half black and half white, averaging to 128 works perfectly. But in a predominantly bright or dark scene, the camera will get it wrong - that's where you come in.
Understanding the Histogram
The histogram is a graph showing the distribution of tones in your image. The left side represents shadows (blacks), the right side represents highlights (whites), and the middle represents midtones.
Reading Your Histogram:
- Spike on left edge: Shadow clipping (lost detail in blacks)
- Spike on right edge: Highlight clipping (blown out whites)
- Gap on left: Image may be overexposed
- Gap on right: Image may be underexposed
- Balanced spread: Good tonal range captured
Screen Brightness Warning
While judging the exposure of your image, remember that the brightness of your screen on your camera can affect your perception of the image's exposure. The brightness can be adjusted for different shooting environments - so don't completely trust your screen for exposure. This is why our histogram is so important. It's a true representation of the exposure of your image.
Steps to Take a Base Exposure
The 4-Step Process:
- 1. Take your first shot in Aperture Priority mode with meter in the middle (0)
- 2. Read the histogram to see if there is any clipping in highlights or shadows
- 3. Have a look at the overall histogram - Is the image overall too dark or too bright for the subject matter?
- 4. If you determine the exposure needs adjustment, use the exposure compensation button to make appropriate adjustments (discussed in next step)
This base exposure gives you a starting point. From here, you'll refine using exposure compensation and potentially filters or bracketing - which we cover in Step 6.
Recommended Camera Settings
Also, make sure you have your creative exposure settings set to Neutral or Faithful. This will more closely represent the true image without having the camera add contrast, sharpness, and saturation artificially to your image.
Settings Checklist:
- Metering mode: Evaluative/Matrix
- Shooting mode: Aperture Priority (Av/A)
- Picture style: Neutral or Faithful
- ISO: 100 (lowest native ISO)
- Histogram display: Enabled on review
- Highlight warning ("blinkies"): Enabled