History of the Photographic Lens

Historic Camera

Historic Camera Collector Club

1889, London
by E.J. Wall

Fig. 3 is the representation of the prisms forming a double concave, and the divergent action of such prisms or lens upon the rays of light.

It is obvious that by combining the two lenses the convergent or positive action of the one may be counteracted by the divergent

or negative action of the other. It is upon these principles that the whole of the modern lenses are calculated. As soon as it was announced in 1839 by Daguerre and Fox Talbot that they had been enabled to obtain a comparatively permanent image in the camera obscure, the ability and skill of mathematicians and opticians were brought into play to produce lenses which should be free from the objections common to the double convex lens which was the only one used in the camera obscure in those days.

The single lens was replaced by the achromatic combination of the telescope. This was eventually reversed, and the plane side presented to the object, as in fig. 5.

Then Wollaston's meniscus (fig. 6) came to be recognised as a means of extending the definition; and in 1840, Chevalier, a Paris optician, still further improved it by a different method of achromatising the lens.

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