The conversation between human and AI assistant.
[|Human|] Provide a bulleted list of the different shapes of lenses
[|AI|] The following are the different shapes of lenses:
- Convex: Curves out from the middle of the lens
- Concave: Curves into the middle of the lens
- Planar: Flat lens
[|Human|] 
Provide a bulleted list of the different shapes of lenses