Some Technical Information


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Technical Information:

Listed here are a few technical items that may be of value to you in the field if you use a field or a view camera. I have prepared these for general use for those who use such cameras. The information here has been of value to me personally in the field. Some of this information was prepared a number of years ago, and other of it was prepared more recently in the context of a course I teach at the University of Massachusetts Amherst that seeks to make the subjects of light and optics clear and relevant to students of art and photography. That course, Physics 125, is introductory in nature and covers many aspects of the science of light including light in nature, lenses, cameras, film, the HD diagram, perception, color theory, digital capture, etc.


Bellows Extension Factor: This is a brief description with accompanying plots that can be copied and transported to the field that will make it easy to determine the increase in exposure that is required for a given situation when the lens is focused on something closer to the camera than infinity. Click here to retrieve it. [A PDF file. This article was published in the January/February 2006 issue of Photo Techniques magazine.]
Limits to Vision: This is a discussion of the primary factors (limitations in the anatomy of the eye and limitations imposed by the physical properites associated with the behavior of light) that are relevant to limitations in sharpness as observed by the human eye. [PDF file, revised April, 2006. A final version of this article was published in the July/August 2006 issue of View Camera magazine.]
Optimal focus and f-stop: This is a discussion of how to obtain the optimal focus when you wish two objects in the scene that are not the same distance from the camera to be in optimally sharp focus, presuming no tilts or swings are used on the camera. The discussion also includes useful charts to help determine optimal f-stops, and a brief summary that can be copied and transported to the field. [PDF file, revised, April 2006. A final version of this article was published in the September/October 2006 issue of View Camera magazine.] A brief summary is also vailable as a separate document. [PDF file]
Bob invites communication about any aspect of these pages or his work: hallock@physics.umass.edu.


Robert B. Hallock
Department of Physics, Hasbrouck Laboratory
University of Massachusets, Amherst, MA 01003
413-545-3529
hallock@physics.umass.edu