Angular magnification is the magnification done by optical instruments with an eyepiece, where the ratio of an angle is delimited at the eye when using the instrument divided by the angular size without the instrument. A simple magnifier achieves angular magnification by permitting the placement of an object closer the eye than the eye's ability to focus in normal circumstances. The normal close focus distance in angular magnification is 25cm.
Angular magnification is the ratio between the size of the angle as seen in the eyepiece and the size of the object's angle object when placed at a conventional closest focal point. In this case, the size of the object is a linear dimension, and the angle is the apparent size. In angular magnification, the linear dimension of the image created in the mind in unstated distance cannot be given. Therefore, the angular size refers to the angle delimited by the object at the focal point. Theoretically, one must take the tangent of the angle to get the real angular size. Practically, this step makes a difference only in cases where the angle is larger than the a few degrees. Angular magnification is about change in image size and ratio of the magnified image to the unmagnified one. Angular magnification depends on the initial viewing conditions.