Hi, I have a problem with my scene, I have a room with a window (no glass) and a corona sun, the problem is: the shadows projected by the sun through window to the floor aren’t accurate, specially in corners, they look rounded.
Searched in forum, corona web page, etc… but I didn’t find an option or solution to that, sorry if it was answered before.
Example with sun settings, render settings are default:
Have you tried reducing sun power? This shadow seems to be a bit burned and this can cause this type of “overflow” 
Cheers.
Do you have a portal in your window?
Yup, just confirming what Rawa wrote. Sun is area light, so it will always blur shadows like this. You can try changing sun size to some sick value like 0,01 and see what happens, but this will not look realistic.
its strange what doesnt look correct when you really analyse something despite it being accurate. i always think of that thread early on in alphas where someone built real lenses and stuck them infront of the max camera and they worked. It reminds me that if ive set it up correctly the corona is always right
OK, thanks.
btw real life sample (photo)
Bugs happens in RL too 
those are the worst, unrealistic clouds, weird shadows/caustics, unrealistic water surface, flickering on horizon, …
