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This image was shot with a Sony E 20mm f/2.8 on a Sony a7. The lens is intended for an APS-C sensor, but I removed a baffle to shoot on the full-frame body.

Sunstar shining through the branches of a tall tree

I understand the basic physics of sunstars. My question is why the sunstars from this particular lens have the giant spokes. This is not due to anything about the composition of this particular shot; the lens always produces sunstars like this.

Edit 1: Yes, the sensor was filthy. Other lenses used around the same time had normal sunstars. I've since cleaned the sensor, and this effect still appears with this lens.

Edit 2: As requested, images of the font of the lens with the aperture at f/16, the smallest available. The first image has a UV filter in place; the second does not.

Photo of the lens, with a UV filter Photo of the lens, without a UV filter

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  • \$\begingroup\$ Is the front element scratched? Or are there directional scratches in the coating of the front element (assuming it has a coating)? \$\endgroup\$
    – scottbb
    Commented Mar 1, 2021 at 17:13
  • \$\begingroup\$ I don't have a magnifying glass or other tool I could use to check for sure. But I don't see any scratches with a basic visual inspection, and haven't noticed any other weird behavior with the lens that might be due to scratches. I purchased this on eBay, but it was listed as New condition and IIRC it seemed like it came in the original packaging. \$\endgroup\$
    – Dan Hicks
    Commented Mar 1, 2021 at 19:27
  • \$\begingroup\$ Do you get the same exact shape when there isn't a pine tree between the camera and the sun? \$\endgroup\$
    – Michael C
    Commented Mar 2, 2021 at 2:53
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    \$\begingroup\$ "This is not due to anything about the composition of this particular shot; the lens always produces sunstars like this." \$\endgroup\$
    – Dan Hicks
    Commented Mar 2, 2021 at 5:11
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    \$\begingroup\$ I'd like to see what the aperture itself looks like at the setting you use to create sunstars because that is a major factor in the appearance of sunstars. \$\endgroup\$
    – xiota
    Commented Mar 2, 2021 at 18:00

1 Answer 1

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Your lens design is not the only thing that affects diffraction, which is what produces sun stars or sun spikes.

Everything between the Sun and your camera that the light from the sun interacts with can diffract light and affect the results.

The shapes and sizes of the pine needles and branches of the tree between your lens and the sun will also play a role.

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