Carl zeiss photomacrography with luminar lenses only . Available to purchase for immediate download. Below is an extract from the manual converted to text for a quick impression on the content. Carl zeiss photomacrography with luminar lenses onlyPhotomacrography with LUMINAR LensesAccording to this formula. the magnification in photomacrography depends on the focal length I of the objective and the optical camera length k. The latter is the distance between the image (film or plate) and the image-side focal point of the objective. Since the location of this focal point is generally not known. it is practically impossible to determine the opti- cal camera length. It is. therefore. necessary to use an easily measurable length for deter- mining the magnification. As suoh we may choose the mechanical camera length b=k+f, the distance between the principal plane of the objective and the image. or - better still the object-to-image distance which can easily be measured with accuracy. The relationships between mechanical camera length. or object- to-image distance - for an objective of a given focal length - and the magnification are shown in the graph on the opposite page. Magnifications are plotted on the abscissa and the values are indicated at the lower edge of the graph in proportional increments (stand- ard magnifications). The difference between two values is 25°/o (or a factor of 1.25). The mechanical camera length or the object-to- image distance can be read off the ordinate. The guide line representing the object-to-image