ASTM F1753-96(2014)

4.1 This specification is intended to ensure uniform classification of the lenses and the marking of scopes to avoid confusion of the consumer, which results form the use of different classification and identification systems.

4.2 This specification is based on the use of the diopter that is the reciprocal of the focal length of the lens as measured in metres.

1.1 This specification covers lenses and scopes used in conjunction with archery bows. It establishes a standardized system for the classification of these lenses in terms of their optical magnification, the marking of the scopes in which the lenses are mounted, and charts depicting the empirical relationship of the apparent magnification the consumer can expect to obtain when a correctly marked lens is used under specific conditions.

1.2 Acuity—The visual acuity of these lenses is related to the magnification of the lens in general. For the average subject there can be an improvement in acuity with lenses having apparent magnifications of 2 to 4× and a decrement in acuity with lenses of 6× and greater.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.