I like to read alone—the more isolated the better. If I had a spaceship and travelled directly away from the sun, but made sure to keep it in view, how far away would I have to go before there wouldn’t be enough sunlight (or light from other stars) to read by? Assume the spaceship stays in more or less empty space; no landing on planets with thick atmospheres or flying into nebulas or black holes.
In an earlier thread, some people could read by the light of the full Moon, and some couldn’t, so I’ll take the full Moon’s brightness as the cutoff. The Sun is about 400,000 times brighter than the full Moon, so you might be able to still read out to sqrt(400000) = 632 times farther away from the Sun, about 632 AU. For reference, Pluto is 30 to 50 AU away depending on where it is in its orbit. That’s farther than I would have guessed.
ETA: Voyager 1 is about 127 AU distant.
I think the fact that the full moon is a disc as seen from Earth while the sun becomes a point source as you move further out is going to have a bearing on ZenBeam’s B.O.E. estimate.
I’ll admit I’m not sure what that impact is.
It was explained to me long ago, in a Heinlein aside IIRC, that even the furthest planets would have plenty of light for things like exploration and colonization. Most daylight on Earth is far, far brighter than we can use anyway, so our eyes screen out a large percentage of it. They would just screen out less (larger iris opening) on Mars or Titan or whatever, and it would seem “normally” bright to us.
Mostly, it just means that shadows will be sharper. I don’t think it would be significant for reading at all.