Final answer:
The lens described as producing an extreme wide-angle effect and distorting straight lines into curves at the edges is a fish-eye lens. These lenses are a type of diverging lens that provides a unique spherical aberration effect and expands the angular magnification and apparent depth within the image.
Step-by-step explanation:
The type of lens that causes an extreme wide-angle effect and distorts the image by making straight lines appear bent or bowed at the edge of the frame is known as a fish-eye lens. This type of lens provides a very wide field of view and due to its distinct convex construction, it often leads to a spherical aberration where straight lines are projected as curved lines on the final image. Unlike a typical rectilinear wide-angle lens that attempts to keep straight lines straight, a fish-eye lens embraces the distortion as a stylistic element in photography and can be used intentionally to create a unique perspective or effect.
The characteristics of a fish-eye lens align well with the keywords related to lenses and optical effects. As light passes through a fish-eye lens, the distortion is enhanced because the lens acts as an extreme form of a diverging lens, which spreads the light rays away from the principal axis, thus exaggerating the angular magnification and apparent depth of the scene.