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At the turn of the sixteenth century Tycho Brahe and Johannes Kepler made single pinhole measurements of the solar diameter. Their accuracy was limited by diffraction (unknown to them) and the motion of the image on the screen. We discuss how two pinholes built on the same mask can be used to bypass all the problems inherent in the single pinhole approach. The distance at which the two images of the Sun are in contact is the only measurement needed, and the experimental accuracy is much better than measuring the diameter of a single moving image. We obtained 0.5% accuracy, sufficient to follow the angular variations of the solar diameter due to the motion of the Earth in its orbit. [ABSTRACT FROM AUTHOR]

Details the construction of a pinhole camera or camera obscura. Designing of pinhole lens; Construction of pinholes; Experimental set-up.

A letter to the editor is presented in response to an article about eclipse pinhole images of a partially eclipsed sun, published in the November 2013 issue.