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Is there a name for the light that passes through a lens and does not make it to the capture medium (sensor, film, other)?
I'm looking for the name of the grey area in the following image from post How does a circular lens produce rectangular shots?
I've searched for the name of what this is called and can not find the answer. I guess this would be similar to overscan on a TV, and sort of the opposite of what causes vignetting in a photo.
Typically one would refer to this as the Image Circle, although that is the entire area which also encompasses the sensor or film area. I'm not familiar with a term that is the area of the image circle that does not include the captured area specifically.
An excerpt of this term in use from page 54 of The Camera - by Ansel Adams:
With a view camera there is another important measure, namely the size of the total image-circle projected by the lens. All lenses, regardless of format, project a circular image, and the rectangular film format must fit within this image-circle. With a small camera, a high-quality image is required only within the film area, and the remainder of the image-circle is disregarded. A view camera on the other hand, requires an image-circle considerably larger than the film area, to allow freedom to use the camera adjustments.
The camera lens projects a circular image that is larger than the image sensor. Not all that circular image will yield a satisfactory image The part of the image circle that yields a satisfactory image is call the "circle of good definition". The diameter of the circle of good definition must be equal to or grater that the diagonal measure of the imagining sensor. The area outside the circle of good definition is called the "circle of illumination".
Excerpt - Textbook "Photographic Lenses" C.B. Neblette Morgan & Morgan Fountain Press, London 1965 - page 127 (image sensor substituted for the word "film".
