Bausch and Lomb Sigmar Lenses for Portrait Photography Thanks to Russell Young for providing this Catalog!!! Bausch and Lomb Sigmar Lenses for Portrait Photography Cover The Sigmar Lens Factors in Portraiture Perspective in Portraiture Perspective in Portraiture Perspective in Portraiture Perspective in Portraiture Depth of Field Depth of Field Coverage Table/Price List Sigmar Diagram by Neblette 1938 p.111