DescriptionLens6b-fr.svg English: For an achromatic doublet, visible wavelengths have approximately the same focal length Français : Avec un doublet achromatique...
choice. This image is a derivative work of the following images: File:Lens6b.svg licensed with Cc-by-sa-3.0-migrated-with-disclaimers, GFDL-en 2008-05-26T08:38:29Z...
