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## Homework Statement

Consider a pinhole camera with depth R = 0.1 m used to observe a solar eclipse. Suppose the sunlight has wavelength [tex] \lambda = 5.8 \times 10^{-7}[/tex] m. Estimate the optimal value of the aperture width w.

## Homework Equations

Hint: balance the geometetrical distortion of the image, which goes to zero as w goes to zero, against the spread of an image point due to single-slit diffraction.

## The Attempt at a Solution

I determined that the approximate spread due to diffraction is [tex]{2R\lambda \over w}[/tex].

But I can't seem to find any mathematical formalism for the geometrical distortion. All I can find are statements about how the image becomes sharper as the aperture becomes smaller (i.e. the statement in 'relevant equation'). But this really doesn't give the precise dependence on w. For example, w and w^2, w^3, w^4... are all possible since they all go to zero as w goes to zero.