Handbook of the practice and art of photography (1875)
Vogel, Hermann Wilhelm, 1834-1898, Molling, Edward F · Philadelphia, Benerman & Wilson · leaf 64
neqal re- fraction of the marginal rays as compared with those of the centre. The margin of the lens is, so to speak, a prism with a much stronger refracting angle than the centre. As the dispersion which the rays suffer increases with the refracting angle of the prism, it follows that the marginal… … Hence, if the ground-glass has been placed at f1, the marginal rays, which have intersected the axis at /3, will form a circle of dis- persion. The diameter of this circle is called the transversal or lateral aberration. It is easily understood that this must be different in two lenses of equal…
Photography
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