Lesson plan
Image circle
area of the photographic film or image sensor. In practice, the edge of the image circle is sometimes less abrupt than shown, and the image quality near the periphery is degraded in more complex ways than is simulated here. The image circle is the cross section of the cone of light transmitted by a lens or series of lenses onto the image plane. When this light strikes a perpendicular target such as photographic film or a digital camera sensor, it forms a circle of light – the image circle. Various sensor aspect ratios may be used which all fit inside the same image circle, 3:2, 4:3, 16:9, etc. A lens to be used on a camera that provides movements must have an image circle larger than the size of the image format (Adams 1980, 54). To avoid vignetting, a photographer using a view camera must ensure that the area remains within the image circle (Adams 1980, 56–57; 151–52; 157–61); a tilt/shift lens or perspective-control lens used on a small- or medium-format camera usually has mechanical limitations that keep the frame area within the image circle.
Article summary
area of the photographic film or image sensor. In practice, the edge of the image circle is sometimes less abrupt than shown, and the image quality near the periphery is degraded in more complex ways than is simulated here. The image circle is the cross section of the cone of light transmitted by a lens or series of lenses onto the image plane. When this light strikes a perpendicular target such as photographic film or a digital camera sensor, it forms a circle of light – the image circle. Various sensor aspect ratios may be used which all fit inside the same image circle, 3:2, 4:3, 16:9, etc. A lens to be used on a camera that provides movements must have an image circle larger than the size of the image format (Adams 1980, 54). To avoid vignetting, a photographer using a view camera must ensure that the area remains within the image circle (Adams 1980, 56–57; 151–52; 157–61); a tilt/shift lens or perspective-control lens used on a small- or medium-format camera usually has mechanical limitations that keep the frame area within the image circle.
Key claims
No claims recorded.
Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
No sources recorded.
Key claims and bibliography are generated from the same tracked claims and sources as the article page.