• Perspective



Kim H. Veltman

Perspective and the Scope of Optics

Unpublished, Toronto, 1992

1. Introduction
2. Ancient Criteria
3. Medieaval Developments
4. Renaissance Perspective
5. Astronomy and Surveying
6. Optics as Extensions of the Eye
7. Conclusions.

1. Introduction
In some senses optics and perspective are very different: optics deals with vision: linear perspective involves representation. A person may be excellent at seeing spatially, and still be hopeless when it comes to drawing spatially in perspective. Yet etymologically, the Latin term for optics and linear perspective is the same (perspectiva). Historically the discovery of linear perspective in the Renaissance brought no clear distinctions between theories of seeing and methods of representation. The terms for optics and perspective remained effectively interchangeable. One important reason for this was that the new perspective instruments which served as drawing aids were also tools for the verification of sight, which became linked with new criteria for proper vision and changed optics from a study of the eye to include extensions of sight. Hence the discovery of perspective in the fifteenth century, the upsurge in measuring instruments during the sixteenth century and the rise of telescopes and microscopes in the seventeenth century are three interconnected developments. Perspective instruments did not simply affect painting practice: they extended the scope of optics, changed the criteria for veridical vision, transformed the very process of objectivity, and hence affected western science as much as art.

2. Ancient Criteria
In classical Greece, optics was primarily concerned with the eye and vision: focussing on psychological questions of how the eye is deceived. Optics was studied in at least three different disciplines. One was medicine and is best known to us through the work of Galen: it concerned the anatomy of the eye and study of the usefulness of its various parts. A second was geometrical optics as found in Euclid's Optics. Its relation to geometry was outlined by Aristotle in the Physics:" While geometry studies physical lines but not qua physical, optics investigates mathematical lines but qua physical not qua mathematical."

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