Magnify

Magnifying glass

The angular magnification of a magnifying glass is defined as the ratio of an angle ε that the image (made by the glass) of an object located at the near point (typically 25 cm away from a human eye) subtends on the retina of the eye to an angle ε₀ that the object (at the same location) subtends on the retina without the glass. The angular magnification is equal to the image size magnification on the retina because of (1) a part of the human eye refracting light toward the retina is considered a thin lens , and (2) a circular shape of the retina; the twice angle between the eye's optical axis and the edge of the image on the retina (circularly shaped) is translated to twice larger the recognized image.