Light radiating from the Sun follows the inverse square law (ie intensity = 1/d*d)
The benchmark value for the Earth at one Astronomical Unit (AU) from the Sun is thus 1/1*1 = 1.
For Mercury 1/0.3*0.3 = 11. The Sun is more than ten times brighter than on Earth.
For Venus 1/0.7*0.7 = 2. The Sun is around twice as bright as on Earth.
For Mars 1/1.5*1.5 = 0.44. The Sun is less than half as bright as it appears on Earth.
For Jupiter 1/5.2*5.2 = 0.036. The Sun is only around 4% as bright as it appears on Earth.
For Saturn, 1/9.5*9.5 = 0.01. The Sun is only around 1% as bright as it appears from the Earth.
For Neptune 1/30*30 = 0.001. The Sun is only 0.1% as bright as it appears from the Earth.
Solar filters typically reduce light levels by 99.999% (ie allow 0.00001 pu through).
We need to rearrange the inverse square law formula to make distance the object (ie d = sqrt (1/i))
sqrt (1/0.00001) = 316 AU or 29 374 000 000 miles.
At this distance the Sun would subtend an angle of arc tan 865 300/29 374 000 000 = 0.0017 deg. or 6 arc seconds (hopefully I haven’t made any mistakes in my maths).