Apologies for the poor formatting, but here are my (unpublished) research notes on light and visibility for DD5. Hope it's useful
3LBBs
Light: U&WA p9
In the underworld some light source or an infravision spell must be used. Torches, lanterns and magic swords will illuminate the way, but they also allow monsters to "see" the users so that monsters will never be surprised unless coming through a door. Also, torches can be blown out by a strong gust of wind. Monsters are assumed to have permanent infravision as long as they are not serving some character.
Sighting Monsters: (Underworld) p9
Players will see monsters at 20 - 80 feet (roll a pair of four sided dice to determine the distance) unless they are surprised by the monster.
Surprise: (Underworld) p9
A Condition of surprise can only exist when one or both parties are unaware of the presence of the other. Such things as ESP'ing, light, and noise will negate surprise. If the possibility for surprise exists roll a six-sided die for each party concerned. A roll of 1 or 2 indicates the party is surprised. Distance is then 10-30 feet.
Example of Referee Moderating Dungeon Expedition: p14
With appropriate variations for ability to detect and/or see what is around them, the adventure will continue in this manner until the party leaves the dungeons or, are killed therein.
Sighting Monsters (Wilderness): p9
Sighting Monsters: Players will see monsters at from 40-240 yards (inches convert to tens of yards for the wilderness) unless the monster has surprised the characters involved.
Surprise: This is the same as in the underworld, except that the distance is from 10-30 yards, and if there are three or more monsters involved they will have moved into a circle around the adventurers. Monsters at 10 yards distance will be able to attack.
DALM
Light:
In the Underworld, generally passages have no light source. In this case, especially for hobbits and men, players must have some kind of light source. A lit torch will permit a player to "see" maximum of 15 feet, after which only dim shadows are slightly visible. A lantern has a maximum range of 30', with similar viewing after this distance. Of course this will make them: seeable to creatures in the darkness.....
Seeing Monsters:
Players will "see" a monster at the maximum range of his light source if unable to see in the dark, or at 90 feet if they can. There is a chance, however, for "surprise" to occur for both parties (die 1 or 2). Certain magical devices will give prior warning,for which see MAGICAL ITEMS in the GLOSSARY.
EPT
1210 The Move in the Underworld p65
Light or some form of magical illumination MUST be present at all times. Torchbearers are needed, thus, or else some player character may be penalised by being made to fight one-handed while clutching a troch. If an "eye" or spell is used to provide light, its operator must keep one had free for this purpose.
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DD5
The Underworld is generally unlit[1] so that players, especially Men and Hobbets, must carry some kind of illumination.[2] Torches, lanterns, enchanted swords, and light spells will illuminate[3] a 30ft radius[4] beyond which only dim shadows are visible.[5] Dungeon denizens are assumed to see well in the dark,[6] however, and carrying light will ruin any possibility of surprising them,[7] except by coming through a door.[8] Note that torches can be extinguished by sudden gusts of wind.[9]
Footnotes:
[1] U&WA p9 (Light): <<In the underworld some light source or an infravision spell must be used>> and DALM <<In the Underworld, generally passages have no light source>>.
[2] DALM <<In this case, especially for hobbits and men, players must have some kind of light source>>. U&WA does not repeat the intriguing phrase regarding hobbits and men, possibly because EGG was reportedly focussed on human player-types at the time. Note that DALM also states explicitly that dwarves and elves can see in the dark; 1974 D&D does not.
[3] CM3 p38 (Magic Swords): <<Magical Swords shed a light of their own over a circle 12" in diameter>> and U&WA p9 (Light): <<Torches, lanterns and magic swords will illuminate the way>>. See also Light, Continuous Light, Darkvision, and other magic spells.
[4] CM3 p38 (Magic Swords): <<Magical Swords shed a light of their own over a circle 12" in diameter>>; DALM <<A lit torch will permit a player to "see" maximum of 15 feet... A lantern has a maximum range of 30'>>; U&WA is tacit on this. However, M&M says (Light spell) p23: <<A spell to cast light in a circle 3" in diameter>>. DD5 simplifies this to a single, 30ft radius for all these light sources.
[5] DALM <<A lit torch will permit a player to "see" maximum of 15 feet, after which only dim shadows are slightly visible. A lantern has a maximum range of 30', with similar viewing after this distance>>.
[6] U&WA p9 (Light): <<Monsters are assumed to have permanent infravision as long as they are not serving some character>>.
[7] DALM <<A lit torch will permit a player to "see" ... Of course this will make them: seeable to creatures in the darkness>> and U&WA p9 (Light): <<Torches ... allow monsters to "see" the users so that monsters will never be surprised>>.
[8] U&WA p9 (Light): <<monsters will never be surprised unless coming through a door>>.
[9] U&WA p9 (Light): <<torches can be blown out by a strong gust of wind>>.