The following image is taken from teaching physics lecture Was man aus virtuelle

Question

The following image is taken from teaching physics lecture Was man aus virtuellen Bildern lernen kann (in German):

enter image description here

Now the cited paper claims that the left hand side is the correct picture to explain the virtual image if you look with your eyes, the right hand side is correct if you use a camera (but incorrect if the camera is replaced with the eye). In the case of a plane mirror both constructions lead to the same result. However in the case of curved mirrors they lead to different results (which is also discussed in the cited paper). Now I am a bit confused since the right picture (with an eye instead of the camera) is that one typically drawn in physics textbooks (for example Pedrotti "Introduction to optics" p.38 or Halliday Resnick "Fundamentals of Physics" p.1140). So my question is, which picture is the correct one? Do you know further references of papers or books which discuss this problem more in detail? (I have only found this cited paper in German)

Explanation / Answer

Both drawings are correct for both the eye and the camera, as optically the eye behaves like a camera. The difference is that the first drawing shows the principal rays while the second shows the marginal rays.

The marginal rays are interesting mostly when discussing focus and depth of field. Compared to most cameras, the eye has a very large depth of field, and a very good autofocus system. Then, the issues of focus and depth of field are less important for the eye than for the camera. That's why the right picture is just slightly less relevant for the eye.

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