Solar, as well as stellar, alignments of corridors in the Great Pyramid at Gisa have lead some archaeologists to interpret them as having been used for astronomical observations while under construction. Solar eclipse observers have noticed for hundreds of years, possibly much longer, the crescent images of the Sun produced when the light from the partial eclipse phases passed through small gaps between the leaves of trees. This short treatise is by no means a proof of some archaeological certainty. Especially in the light of the circumstantial evidence just presented. It is, rather, a unique attempt to illustrate some of the criteria required to ascertain the degree of resolution of sunspots that might be observed using pinhole optics and to discuss a simple experiment in which the derived theoretical results are proved.
Most optical devices rely on refraction or reflection to provide an image on a screen or film plane.
A pinhole camera is a device which uses neither lenses nor mirrors to produce its image, but rather only a small circular aperture, or pinhole . This apparent lack of what one might consider an imaging optic does not mean that such an arrangement of hole and screen cannot produce an image. It does and with the greatest depth of field. What it looses when comparing it to other optical instruments is its light gathering capabilities due to the relatively small aperture to screen distance ratio, i.e. the inverse square law. However, even with this shortcoming it still is a candidate for observing the sky s brightest object, the Sun.