Lecture 16: Camera & Lenses Cont. (28)

What does the negative radius mean in the bottom of the chart?


Notice that some of the right lenses are actually curved in the opposite way as the left lenses. A negative radius corresponds to the center of the corresponding circle/sphere being to the left of curve. This is helpful as flipping whether the optical interfaces are curved in or out changes whether the rays of light are getting closer or farther apart, which is nicely illustrated in the next slide.


I think this is the radius of curvature, so it's the distance from the lens to the center of curvature and if the lens lies to the left of the center of curvature, the radius of curvature is positive and if it is on the other side is it negative.


It's cool to see that the Double-Gauss lens is still commonly used today. The compact size makes it a popular choice of lens for modern-day, portable cameras. I also believe it is in standard prime lenses, such as the 50mm f/1.4 lens and zoom lenses, like the 24-70mm f/2.8 lens. (https://en.wikipedia.org/wiki/Double-Gauss_lens)

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