Archived posting to the Leica Users Group, 1998/08/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]>>>>>>>>>> My question: Does the 75/1.4 M lens provide a significantly more narrow depth of field for portrait work than the 90/2.0 when both lenses are used with their maximum apertures? <<<<<<<<<< Richard, You might want to check out the Depth-of-Field Calculator at http://www.serve.com/ballen/DOF.html or http://www.syspac.com/~gillettm/DOF.html According to the calculator, at 3 feet, depth of field for the 75 at f/1.4 is .45 inches. At 20 feet it's 1 foot 9.6 inches. Depth of field for the 90 at f/2 and 3 feet is .44 inches, and at 20 feet is 1 foot 9.38 inches. By comaprison, depth of field of an 80 mm R lens at f/1.4 and 3 feet is .39 inches and at 20 feet is 1 ft 6.96 inches. All are close. But (assuming this calculator is accurate) you'll find the 80 at 1.4 has the shallowest depth of field, even shallower than a Noctilux at f/1. Larry