Question

the power of lens is - 3D what is its focal length​

Answer 1

Answer:

While analyzing 3D-2D transform we are taking the focal length as the distance to image plane. ( In almost all the reference). Focal length of a lens is actually the distance between center point of the lens to the point on the optical axis where the parallel lines will converge.

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Answer 2

Power of leans = -3D

Power of lens =1/ focal length

-3= 1/f

f =-1/3