Enter the shutter speed that exposes the darkest shadows of the scene. Then, the shutter speed that exposes the highlights.

You can measure the shutter speed with your camera’s spot meter:

• Set your camera to Aperture Priority (A) mode.
• Make sure the Metering Mode is set to 'Spot Metering'.
• Position the focus point over the darkest part of the scene. Read the shutter speed and enter it in the first field (Shadows).
• Position the focus point over the brightest part of the scene (avoiding sun reflections and light bulbs). Read the shutter speed and enter it in the second field (Highlights).