- Where are the light values? Look for the lightest areas on the object. The very brightest of the lightest values are called highlights.
- Where are the dark values? Dark values often reveal the sections of the object that are in shadow. By locating shadows, you can usually identify the light source.
- Where is the cast shadow? The section of the cast shadow closest to the object is usually the darkest value in a drawing. By locating an object's cast shadow, you can easily discover the direction from which the light source originates.
Each time you reposition the light source, identify the following:
- The shadows on the object (dark values)
- The brightest areas (the highlights)
- The light values (areas closer to the light source or not in shadow)
- The cast shadow (the darkest values)
Constrast
Your drawings can appear flat rather than three-dimensional when you use too little contrast in values. Unless you are trying to achieve a specific mood or want the subject to look flat, always use a full range of values.