Various lens shapes, and the location of the principal planes.ʟ̩
&lt;br'&gt; Converging or positive lenses.
1 - Symmetrical double convex lens.
2 - Asymmetrical double-convex lens
3 - Plano- convex lens.
4 - Positive meniscus lens.
Diverging or negative lenses.
5 - Symmetrical biconcave lens.
6 - Asymmetrical biconcave lens.
7 - Plano-concave lens.
8 - Negative meniscus lens.

Original figure: https://commons.wikimedia.org/wiki/File:Lens_shapes.svg
Own work
OwlTheCat