Low-Light, Darkvision and nightfall

Question

I can't seen to find the relevant rules to make this clear for me: low-light vision specifies that its bearers can "see twice as far" as a human in conditions including moonlight and starlight, and the elf racial description says that an elf in moonlight sees as well as in sunlight. What I'm trying to find out is how far is a human able to see in conditions of moonlight or starlight; i.e. just how far is low-light vision going to allow you to see above ground at night?

Darkvision tends to be capped at 60 ft., which seems to be a disadvantage aboveground when compared to an elf's low-light vision, yet the Flaw "Beady Eyes" from Dragon #328 "downgrades" darkvision to low-light vision, a seeming upgrade if one does not spend their time spelunking.

So, just how much better than darkvision is low-light vision above ground at night?

Answer 1

The extraordinary ability low-light vision is a mess...

The elf racial trait low-light vision says

An elf can see twice as far as a human in starlight, moonlight, torchlight, and similar conditions of poor illumination. (PH 16)

The Player's Handbook on Vision and Light adds that one should

Double the effective radius of bright light and of shadowy illumination for such characters [that possess low-light vision]. (165)

The Monster Manual provides a similar description of low-light vision that's slightly more explicit:

A creature with low-light vision can see twice as far as a human in starlight, moonlight, torchlight, and similar conditions of shadowy illumination. (311)

And the Dungeon Master's Guide provides a description of low-light vision:

Characters with low-light vision have eyes that are so sensitive to light that they can see twice as far as normal in dim light. [...] Characters with low-light vision can see outdoors on a moonlit night as well as they can during the day.

Finally, the Rules Compendium provides another description of low-light vision:

Creatures that have low-light vision can see twice as far as normal in dim light. ... Those that have low-light vision can see outdoors on a moonlit night as well as a human can during the day. (115)

In other words: Yuck, or Ask the DM.

...But you can probably safely just take the best parts

The light levels poor and dim aren't listed Table 9–7: Light Sources and Illumination (PH 165), but shadowy totally is. And while torchlight can be either shadowy or bright illumination according to the same table, moonlight and starlight aren't even on the table.

So from the Player's Handbook section on Vision and Light take double the effective radius of bright light and shadowy illumination, from the Monster Manual description take starlight, and from the Dungeon Master's Guide description take see outdoors on a moonlit night as well as they can during the day. Put them in a Word Blender. Pour out...

Low-light Vision (Ex): A creature with low-light vision can see twice as far in bright and shadowy illumination. It can see outdoors on a starlit or moonlit night as well as a human can during the day.

When the torches go out (or whenever the DM says the night's overcast), such a creature is still blind, which is the rather severe downside of low-light vision. (I'm not sure discussing low-light vision with regards to flaws is entirely fair, given that one can always mitigate one's flaws simply by playing differently.)

"But how far can a human see in moonlight?"

Effectively, creatures can see as far as one of us humans actually can... that is, until the creature needs to use the skill Spot to determine the location of enemies.

The skill Spot isn't used to determine the literal distance a creature can see but how far away a creature can detect enemies. Each terrain has a Stealth and Detection entry that's used when determining the distance at which encounters effectively begin. For example, Stealth and Detection in a Forest says

In a sparse forest, the maximum distance at which a Spot check for detecting the nearby presence of others can succeed is 3d6×10 feet. In a medium forest, this distance is 2d8×10 feet, and in a dense forest it is 2d6×10 feet. (DMG 87)

So the DM determines the distance randomly. Then according to the skill Spot

The Dungeon Master may call for Spot checks to determine the distance at which an encounter begins. A penalty applies on such checks, depending on the distance between the two individuals or groups [a −1 penalty per 10 ft.], and an additional penalty may apply if the character making the Spot check is distracted (not concentrating on being observant) [a −5 penalty]. (83)

But the DM needn't call for such Spot skill checks and just declare the encounter begins. Further, if one or more creatures are in shadowy illumination those creature have concealment and can use that to make Hide skill checks, probably substantially reducing the chances they'll be noticed by an unobservant sentry making a Spot skill check. If one or more creature is in darkness then I hope you like rules.

D&D 3.5 never says exactly how far folks can see. Instead, the game explains how far away folks can see the next pile of XP.

Answer 2

All of the information you're looking for on vision can be found here

Moonlight doesn't naturally simulate a light source. It's automatically considered as a "Shadowy" condition, which changes the effect of lights in the area.

For example, if you have a torch out in the moonlight, Your humans and characters without Low-Light Vision can see out to 40ft before anything beyond is treated as darkness. Characters with Low-Light Vision can see as far as they would be able to during the day, and Characters with darkvision are limited by their darkvision range. Anything beyond that is essentially darkness as well.

A torch sconce in an unlit dungeon with a lit torch produces the same amount of light as it wound under the moonlight. Since both areas are considered shadowy. Any area you can't see into is considered darkness, and in these areas your character is effectively treated as Blinded.

If you have no light source, Darkvision is always better, if you're in a situation when you're attempting to be stealthy, Darkvision is always better, if you have a light source and its important that you are able to see a long distance in a dark area, Low-light vision is superior.

The only instance in which darkvision isn't superior is when you get into advanced detection methods like Blindsense, Tremorsense, and Blindsight.