Couldn’t find some clear pictures that explained how images are flipped by a lens. There are pictures and articles for sure but they just weren’t clear to me. So I rigged up a lens and tested it out.
Test Setup-Shows how image is flipped by lens

Test Materials
- LED Desk Lamp
- Letter R printed on wax paper with red marker
- 50mm lens from 35mm SLR camera
- Cardboard screen
View from- Rear of lens- At Letter R-

This would be the way you would see the object using your eyes. The letter R is in front of you in the correct orientation as you would read it. The letter R is often used for this type of demonstration as its orientation cannot be confused.
View from- Behind Image, Thru Lens, At Screen

Close up picture shows how the image on screen or film would be rotated 180 degrees and then flipped