Zoom lenses for narrow-gauge cine cameras, Jos. Schneider Optische Werke GmbH

Zoom lenses for narrow-gauge cine cameras

Fig. 1:
Variogon 1.8 / 8 - 48 mm
for normal-8-narrow-gauge
film with reflex viewfinder

The history of the Variogon zoom-lens is closely tied to that of the narrow-gauge cine film era. An impeccable sharpness of focus right into the corners of the image, even with varying focal lengths, was a basic precondition of its success.

The first lenses with variable focal length for narrow-gauge cine cameras appear as early as the year 1937; they were used on a 16-mm Siemens camera. Wider use, however, only became possible beginning in the fifties, through the use of computers.

This development ran parallel to technical progress in the anti-reflection coating of optical lenses. Because of the relatively large number of lens elements, the high degree of transparency of the glass became especially important.

Even at the time of the normal-8-format ( 3.6 x 4.9 mm²), almost all manufacturers of narrow-gauge cine cameras in Europe made use of the Schneider-Variogon.

The first types that time:

Variogon 2,8 / 10-40 mm,

Variogon 1,8 / 9-30 mm,

Variogon 1,8 / 7,5-37,5 mm,

Variogon 1,8 / 8-48 mm.

With the introduction of the Super-8-format on the market, a larger picture format (4.22 x 5.69 mm2) was possible, and with it a picture area about 40% larger, which in all areas, and even at full aperture, was distinguished by its sharpness.

The underlying principle of this type of Variogon was based on the mechanically compensated focal distance adjustment. In this system, mechanical radial cams move two lens groups according to mathematical-physical guidelines I and II relative to one another - in Fig. 3 represented by blue lines - in order to continuously change the focal length of the lens. As a result, the locus of the picture always remains in the same position, the film plane. The camera-to-subject distance is set with the front group of lens elements.

	Fig. 2: Because of the construction and the optical-mechanical action, the locus of the picture remains remains constant, and the picture quality is largely maintained.

With lenses with a viewfinder - see Fig. 1, - a beam splitter is situated in front of the iris
diaphragm.

An overall view of the Variogon and Optivaron lenses from our earlier product line for Super-8-narrow-gauge cine cameras is presented in a

brochure.

What is remarkable is the 30-fold zoom lens that was made at the end of the seventies for Beaulieu Cameras:

Variogon 1,8 / 6 - 180 mm

Enlargement by mouse click!

Fig. 3 right:
Principle of function of the mechanical focal distance adjustment

Variogon zoom lens