Polaroid SX70 manual Introduction, Power Source, Lens, Viewing and Exposing System

II - THEORY OF OPERATION

A. INTRODUCTION

A general description of the camera and the sequence of its functions is contained in Section I. In that section, detailed analysis of individual assemblies and electrical circuits was minimized so that emphasis could be placed on the intenelation-ship of various functions. In the following paragraphs, the individual groups of components are described in greater detail. The description are presented in the sequence in the commponents were mentioned in Section I.

B. POWER SOURCE

Power for the drive motor, the shutter electronics, and the flash array is supplied by a specially designed 6 volts battery incorporated in each 10 exposures film pack. When the pack is inserted into the camera, two contacts pads on the bottom surface of the pack engage two spring-loaded contacts on the inner bottom surface of the camera bottom plate. From these two points, it is distributed to its destinations by the copper foil strips of a flex circuit on the outer surface of the bottom plate.

The battery has adequate capacity to expose all 10 film frames with at least six months of expected shelf life.

C. LENS

The lens employed is a four element, glass lens of f/8 aperture with a focal lenght of 115mm. It has a focusing range of infinity down to 10,4 inches. Focusing is accomplished by movement of the front element only. Helical threads in the lens mount provide the linear lens elemet movement. Operation is by means of a geared focus wheel at the top of the shutter housing. There is no manualy adjustable diaphragm associated with the SX-70 lens.

D. VIEWING AND EXPOSING SYSTEM

When the camera is erected to picture taking configuration, the subject can be viewed through the collapsible viewfinder. Figures 2-1 and 2-2 show the two optical paths in the camera. Note the direction of the arrows. Reflected light from

Figure 2-1 Viewfinder optics (viewing)