Size
The diameter of the filter thread for mounting on the lens. Different models of lenses have different dimensions, and accordingly, the sizes of “seats” for light filters also differ. In modern photographic equipment, a set of standard diameters is used, in the range of about 27-82 mm.
Magnification factor
This parameter is specified for
macro filters(see "Type"). The magnification factor is expressed in diopters (d) and indicates the optical power of the lens (which the filter actually is). The larger the magnification factor, the stronger the filter reduces the minimum focal length and the closer you can place the lens during macro shooting.
