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Lecture 15: Cameras and Lenses (67)
wangcynthia

As stated in lecture, Gauss's Ray Tracing helps us derive the thin lens equation. If we have an object in the world, Gauss' figures out where to put the sensor on the other side of the lens so that we can focus on that object in the resulting image.

tanmayghai18

In addition, Gauss's Ray Tracing can help us show that the three rays (parallel, chief, and focal) intersect at the same point as shown in the image on this slide. This "point of intersection" acts as the point of the "virtual image".

sirejdua

In lecture, it was mentioned that all rays that pass through the object (represented by the arrow on the left) that go through the thin lens converge onto the point on the right. Why is this the case? I know that the thin lens assumption is that all parallel rays converge to the focal point, but how is that used here?

Turese

When it says "all parallel lens go through the focal point", what are they parallel to? Each other? Does that mean there are multiple focal points?

Turese

As it turns out I was reading this diagram very wrong and didn't realize that object was referring to the black line on the left with the arrow. I thought those lines were completely arbitrary.

michellebrier

Is the focal point on the sensor, which is on the "Image" side of this diagram? And the focal distance is the distance between the "Image" point and the lens? (EDIT -- nevermind, I was looking at this incorrectly)

michellebrier

Also, this helped me out with understanding the "parallel lens" property: https://www.physicsclassroom.com/class/refrn/Lesson-5/Refraction-by-Lenses. I think it's used here to get the focal point, and then we use the fact that rays from the same point on the object plane will always be focused on the same point on the image plane, no matter where they pass through the lens, to get the object's convergence in image space.

chenwnicole

Ran into this paper, seems pretty helpful with understanding this ray tracing construction http://bolvan.ph.utexas.edu/~vadim/Classes/2010f/rays.pdf

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