Macro lenses in reverse position

Enlarging lenses are optimized for high imaging performance in the close-up range. That's why this lenses are specially predestined for macro imaging. The range of magnification from |ß'| = 0,1 – 2 in the normal position (Fig. 1: the front lens is turned to the object) will be extended up to |ß'| = 1 – 5 in reverse position (Fig. 2: the front lens is turned to the film/sensor).

      Fig. 1 Lens in normal position, minified image

Installation

Due to the large diameter of the front lenses, an extension tube with the following minimum length must be installed between the lens and the helical mount, when the lens is used in the reverse position:

As a result of the long rear mount of the Apo-Componon 4.5/90, extension tubes at least 18 mm long must always be installed between the lens and the helical mount.

      Fig. 2 Lens in reverse position, magnified image

In order to identify lens type and mounting position while the accessories ring is removed, all lenses are designated with aperture and focal length at their rear mount.

Since the fullest aperture openings of the individual lenses differ, the aperture rings of all the lenses are uniformly marked 1 to 6. In position 1, the aperture is fully opened. Each higher number closes the aperture by exactly one f/stop. Half F/stops are designated with a dot.