empty magnification

In optics, magnification refers to the size of an image in comparison to the object that created it. There are several types, including linear magnification (ratio of image length to object length), longitudinal magnification (size increase along the optical axis), and angular magnification (ratio of angles subtended by object and image). While there's no theoretical limit to magnification, practical limits are imposed by an optical system's resolving power, its ability to distinguish between closely spaced objects. "Empty magnification" occurs when an image is enlarged without a corresponding increase in resolution, meaning finer details cannot be discerned. This can happen if the optical system's numerical aperture is insufficient to capture the diffracted light necessary to resolve fine details.12