AGFA Automatic 66 Instructions For Use Manual page 5

The principle of the Agfa Automatic 66
With the Agfa Automatic 66 we are giving you a camera that, for the first time, uses a
built-in exposure meter to regulate the shutter speed fully automatically.
It should be expressly pointed out that working with the camera does not require any
knowledge of the function of the automatic mechanism. If we nevertheless give a brief
explanation of its operation, it is not least because of the lively technical interest shown
in this new feature.
It can be assumed as known that light meters use light-sensitive photoelectric cells, which
show the amount of light hitting the cell converted into exposure and diaphragm values
via a galvanometer by means of corresponding needle deflections.
With the construction of the Agfa Automatic, it has been possible to make this needle
deflection the starting point for automatic shutter speed control. The process now taking
place can be compared with the mode of operation of an air pump, the air inlet
opening of which is adjustable and the piston of which is under spring tension. At the
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