title: Significance of selection of Petzval curvature in triplet design.
abstract: The significance of proper selection of Petzval curvature P in the Cooke triplet design has been investigated. Seven triplet systems at 100 mm, f/5.0 for a 35-mm camera, have been designed for seven different values of P (0.0037-0.0002-0.0049), and their performances are evaluated and compared. It is observed that the performance of the triplet does not vary linearly with the value of P. The triplet designed with a value of P = 0.0043 gives the best performance. Its performance deteriorates rapidly for designs developed with P values lying on either side of this optimum value.
authors.forename: K D
authors.initials: KD
authors.lastname: Sharma
authors.forename: S V
authors.initials: SV
authors.lastname: Gopal