In eevee, the soft shadows of the sun have circular pattern artifacts

The angle value has been increased to get soft shadows with sun.
As the rendering progresses, the shadows appear to spread smoothly, but soon there are circular pattern artifacts.
This looks like a step phenomenon or constant interpolation.
I tried to manipulate all the values of the light and render properties, but couldn’t improve the artifacts.
How can I improve this problem?
I’ve attached two blend files that I set up to help you solve my problem.
Work was done in blender 2.81.

eeveeSunCircularArtifacts01.blend (159.9 KB)
eeveeSunCircularArtifacts02.blend (103.7 KB)

For Sun lamp you use a value for “angle” more adjusted to reality.
0.5 is by default.
Soft shadows for Sun lamp in Eevee will not behave very well for very large (not real) angle values.
I’ve also noticed that soft shadows on final render looks much better than viewport no matter if they have the same samples value. This must be by design, to privilege speed in real time.
Just in case you could report the problem to see if excessive banding in viewport at very high sample values is a bug or by design.

You see sun shadows in real life, they are hard shadows, not as soft as one might think.

Thanks YAFU.
As you said, no artifacts occurred in the F12 render.
This difference, even though the preview and final render have the same sample value, means that eevee is simplifying something to speed up viewport rendering.
Meanwhile the advice on the realistic angle of the sun is also interesting.
I’ll note.

0.5 degree is the angular size of the sun disk. The size you would see if looking through sun blocked telescope/binocs. Do not watch the sun through telescope/binocs without a sun filter!
0.5 degree is not however, the size you perceive the sun to be, as that includes the corona and atmospheric conditions.
0.5 degree is the minimum size you should use, but you can use bigger and compensate by lowering the strength, to simulate corona, or hazy/cloudy conditions. I use this to my advantage in Cycles if the true sun becomes problematic - increase the size and lower the strength significantly will produce less noise. Excuse will be “it was slightly overcast” :smiley:

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