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Keywords from Image Description:
Achromatic lens.svg achromatic lens crown flint focus of violet without flint focus of red without flint focous of both with flint Achromatische Linse Kronglas Flintglas Fokus des violetten Anteils ohne Flintglas Fokus des roten Anteils ohne Flintglas Fokus beider Anteile mit Flintglas Own Andreas Lens diagrams