Why does the sun appear hexagonal in a photo, and what does that reveal about the lens?
Asked 3/9/2011
210 views
2 answers
0
In a photo, the sun appears as a hexagonal shape rather than a circle. What does that indicate about the camera or lens that captured the image? Does it reveal anything about the aperture, aperture blades, or sensor?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
15y ago
2 Answers
48
It tells us that the aperture contains either three or six blades and that where these blades meet there is a corner which results in Fraunhofer diffraction. This is discussed mathematically in Physics SE.
It also tells us that the lens was stopped down, as if it were wide open there would be no corners to cause diffraction, regardless of the number of aperture blades.
Incidentally the number of (distinct) points to the star is equal to double the total number of unique orientations* in the sides of the aperture shape i.e. three blades would be six points, six blades would also be six points as a hexagon has only three unique orientations in its sides.
* a hexagonal aperture has six sides but only three unique orientations as there are three pairs of parallel sides.
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
15y ago
0
Generated from our catalog & community — verify before relying on it.
A hexagonal sun shape usually points to the lens aperture, not the sensor.
It indicates the lens was likely stopped down, so the aperture blades were shaping the opening instead of the lens being wide open. A hexagonal highlight or diffraction/star pattern suggests an aperture with about six blades (theoretically three can also produce a six-point pattern, but six is much more likely in real lenses).
It also suggests the blades are not strongly rounded at that setting, because rounded blades would make the opening look more circular.
More broadly, flare shape is influenced by the aperture shape, while the overall flare character depends on the lens design and elements. A star filter could create a similar effect, but that is less likely.
So the main takeaway is: the image likely came from a stopped-down lens with a roughly six-sided aperture opening.
Recommended products
UniqueBot
AI15y ago
Your Answer
Related Questions
Why is a bright geometric shape appearing in every photo from my Canon 70D?
Why doesn't stopping down the aperture crop the image on the sensor?
Do beveled or rounded aperture blade edges improve image sharpness?
Why do aperture blades create sunstar rays, and why do odd blade counts produce twice as many?
What aperture blade shapes are used in lenses, and how do they affect bokeh?