scope:

This specification covers one type of 24 inch f/4.0 lens, 9 × 9 inch format, aircraft reconnaissance camera lens cone designated LA-57A.

A production issue number will be placed following the suffix letter in the type designation. This number will be established in accordance with the provisions of MIL-STD-155 and will be furnished when required upon application by the contractor to the procuring activity after the award of each contract. This complete type designation will then be used on nameplates, shipping records, in instruction books, and wherever reference is made to the specific equipment defined by the complete designation.

intended Use:

The 24 inch f/4.0 lens, 9 × 9 inch format, LA-57A is intended for use in taking night photography and in the RB-56.