Sing Conventions
1. Converging or convex lens
• focal length is positive
• image distance is positive
when on the other side
of the lens (with respect to
object)
• height upright is positive,
inverted is negative
2. Diverging or concave lens
• focal length is negative
• image distance is always
negative
(on the same side of the lens as
the object)
• height upright is positive,