Rules for Light Sources

[korgoth]

Hey, folks. I may simply have passed over them, but I don't see in Volume III where the ranges for torchlight, etc. are stated. Did I miss it?

[coffee]

korgoth said:

Hey, folks. I may simply have passed over them, but I don't see in Volume III where the ranges for torchlight, etc. are stated. Did I miss it?

In my (6th printing) copy they're on page 9 (such as they are).

'"Torches, lanterns and magic swords will illuminate the way, but they also allow monsters to "see" the users so that the monsters will never be surprised unless coming through a door.'

Does that help?

[korgoth]

coffee said:

korgoth said:

Hey, folks. I may simply have passed over them, but I don't see in Volume III where the ranges for torchlight, etc. are stated. Did I miss it?

In my (6th printing) copy they're on page 9 (such as they are).

'"Torches, lanterns and magic swords will illuminate the way, but they also allow monsters to "see" the users so that the monsters will never be surprised unless coming through a door.'

Does that help?

So it's never spelled out that a torch illumines a 30' radius, etc? Just wondering if I failed to find that, or if it simply isn't there to be found.

[coffee]

I think all that wasn't specified until the DMG, for AD&D. OD&D was a lot looser and common sense prevailed over actual rules.

It's one of the reasons the books could be so small.

[korgoth]

Thanks! I know those rules are in Moldvay's Basic as well.

I guess I'm just spoiled.

[Finarvyn]

Yeah, rules such as these were never really spelled out. I suppose there was the assumption that in a dungeon things would be twisty and turny to the point where a torch illuminates at best the room or section of hallway where you currently stand.

We always played a "torches on means area is lit" versus "torches off means area is dark" and never actually bothered to count squares or pin down specific rules.

[thorswulf]

I never really bithered with it either. I mean, do you really want to go to the trouble of cutting out a a 3" or 6" circle out of black paper, and place it around miniatures? No I didn't either.

[foster1941]

When this would matter would be when in either a long hallway or a large room a monster can see the party but they can't see it -- standard encounter distance is 20-80' and if we assume torches and lanterns illuminate an area approx. 30' radius (which is, IIRC, what later editions say) that leaves considerable room for monsters lurking in the shadows -- the party will be able to hear them (since they weren't surprised, otherwise the encounter distance would've been 10-30') but they can't see them...

[ffilz]

Actually, they might even be able to see that something is out there, but not sufficient to identify what it is.

It's interesting that bits like this aren't addressed because certainly they must have arisen in the early play that preceeded editting D&D. I suspect that bits like this were felt early on to need lots of GM discretion and they didn't feel like they could properly address that in the rules.

It's trying to codify things like this that I think distract from the essential simplicity and workability of the D&D play model. If you get all caught up in realism etc. the whole game model crumbles apart. Far easier to just pick a simple model that allows for play and move on.

So perhaps the easist way to address this is something like:

Generally a torch illuminates enough that the PCs can see the general outlines of rooms and passages and major features including monsters. Obviously a torch, or even infravision has some limits to visibility and the GM is free to put constraints on a case by case basis.

The just assume that the non-surprise encounter distance does allow identification. Perhaps something in the environment allows the PCs on occaision to see as far as 80' even with illumination limited to a few torches. Maybe there's some phosphorescent moss, or perhaps the monster's damp skin glistens.

And of course I think it's always reasonable to borrow from other games or newer editions to resolve issues in the early editions.

Frank

[coffee]

ffilz said:

Actually, they might even be able to see that <b>something</b> is out there, but not sufficient to identify what it is.

Yeah, they'd be able to see the evil gleam of its eyes, but that's about it. Adds a lot of atmosphere, that way.

[philotomy]

The claustrophobic, torch-lit atmosphere is always something that I try to convey, because it so easily falls by the wayside when the players are looking at nice neat lines on graph paper or a battlemat. I typically describe torchlight as illuminating a 20' radius with decent clarity, with some dim, shadowy illumination out to 30'. Beyond that little circle of light, it's black, unless there is something out there to reflect the light.

[thorswulf]

I'll second that. There was an old bomb shelter behind this house a buddy andI checked out with a flashlight. Even a 20'x20' room is dark and creepy.

[tgamemaster1975]

thorswulf said:

I'll second that. There was an old bomb shelter behind this house a buddy andI checked out with a flashlight. Even a 20'x20' room is dark and creepy.

I know what you mean, I was through the basement area of the old White Motor company in Cleveland OH, oh about 25 years ago and there were down to a low operating level at the time, and I walked with a maintenance guy through many tunnels/basement with long corridors that had water leaking from the ceiling in many areas, water on the floors, poorly lit with rooms the same way. The corridors were not the much different in size from a sterotypical dungeon and I remember at the time having two thoughts, one was about now much this was like a D&D sans monsters/treasure and what a great Halloween haunted house it would make.

[coffee]

I actually got to try it out this evening; out power went out. I knew I had a flashlight in my jacket pocket, so I got that, and we lit candles. It was different, but not scary, but that's at home, where we know the place well.

If I had been in a strange place with no light, it would have been a very different thing.

Darkness is still one of the main fears people have, and with good reason.


Also, I'd like to take this opportunity to debunk the Hollywood myth that you can light up a whole area (like a tunnel) with a Zippo lighter. I've tried it in real life, and all it does is accentuate the gloom.

[Thorulfr]

coffee said:

Also, I'd like to take this opportunity to debunk the Hollywood myth that you can light up a whole area (like a tunnel) with a Zippo lighter. I've tried it in real life, and all it does is accentuate the gloom.

The main problem with candles, etc., is that you have to keep the flame out of your line-of-sight. The flame will dazzle you, wiping out your night vision. That's why you have your torchbearer hireling standing behind you.

Cribbing from the book I did for Call of Cthulhu, an 8" wax candle will burn for about 8 hours in still air, and a tallow candle would burn for about 7 - but only if it was trimmed every 15 minutes or so (otherwise the wick will get too long, making the flame gutter, smoke, and burn too fast.) In medieval times, wax candles would likely need trimming as well, but not as frequently as tallow candles...I don't know if anyone has written up any practical experiments with old-style twisted wicks.

There was also a common thing called 'rushlights,' long strips of reed pith soaked in grease. Anyone interested in some stats? (gotta go read to my son and put him in bed now)

(edit: fixed typo)

[makofan]

On pgae 9, it says monsters will be encountered at a distance of 20'-80'. So that seems to give the idea that beyond 30' you can see some type of movements

[philotomy]

Huh, it even says "Players will see monsters at 20-80 ft...unless they are surprised."

Nevertheless, I'd overrule the die roll in any situation where vision was limited (by a corner, by limited lighting, or whatever). I'd either say the PCs know the monster is there by other means (hearing, smell), or I'd make vision limit the max. encounter distance, for this particular case.

(Or I'd let the encounter distance stand, and if it was beyond the party's light, I'd say they saw their light reflected (off armor, off eyes, off something) -- so they're not surprised and know *something* is there, but can't tell exactly what...)

[murquhart72]

I believe it was assumed you could see with torch/lantern light period, but only clearly enough for details within 10' to 30' or so, everything else being mere shadows or an hyperactive imagination
Lanterns lasted longer, but were more expensive and may (in warmer climes) use oil.

[Zulgyan]

Jul 23, 2017 17:32:12 GMT -6 murquhart72 said:

I believe it was assumed you could see with torch/lantern light period, but only clearly enough for details within 10' to 30' or so, everything else being mere shadows or an hyperactive imagination
Lanterns lasted longer, but were more expensive and may (in warmer climes) use oil.

Coolest explanation ever.

[Scott Anderson]

A magic sword or a candle provides enough light for one person to see what he is doing.

A torch provides enough light for two people to see what they are doing.

A lantern provides enough light for three people to see what they are doing.

Use common sense about how far you can see; probably 20-30'

[tetramorph]

Scott Anderson, I like how you make it about number of people rather than distance in diameter.

That means: who gets to have a weapon in hand and who is busy holding the light source.

A lantern would help a lot, in this case. I think I would rule that you can't see behind you with a torch pointing forward.

[rustic313]

Given that encounters can occur out to 8", I rule that torches and omnidirectional lanterns illuminate with shadowy light to 8" and bright illumination to half that distance.

I also run with 1" = 5 feet ( or one pace) so ymmv.

For reference a cruddy 40 watt bulb puts out more than twice as many lumens as a midsize oil lamp. Go get a cheap 25 watt bulb at the hardware store and you have 200 lumens, probably the typical case for small handheld oil lamp technology... A 40 watt bulb would be likely best case with 450 lumens. A 60 watt bulb with 800 lumens is on par with a heavy duty railroad lantern or a storm lantern. I also have one of those and it would be a pita to carry all day much less fight with, about 5 lbs filled. But with about 10 bucks and a dark evening you can pace off some distances pretty easily using the lightbulbs.

I have an oil lamp with a single 3/4" wick, or about 100 lumens, and it puts out about a 15 foot circle sufficient to see detail, best case, with shadows out further. It drinks about 3/4 oz an hour so a pint of lamp oil lasts 24 hours more or less.

So, all that said, I feel pretty comfortable that 4/8" ( 20/40') is reasonable in game terms and also in real life. If a party used a large storm lantern (for example, in as static position o r if they paid the enc price to lug it) I might expand encounter distance to 12" i.e. 2d6.

[delta]

I appreciate folks pointing out the "see monsters at 20-80 feet" rule in Vol-3.

I ran into a snippet from an old Scientific American article, circa 1888, that said, "A good light is obtained by spacing them [torches] 20 or 30 yards apart" (link). If we take half the distance between these torches we get 37.5 feet (25 × 3 / 2), pretty close to the AD&D radius of 40 feet. I suppose if that's "good light", then we could reasonably justify "dim light" at something like 80 feet.

Personally, for a while I've been using 30 feet illumination to keep things in multiples-of-threes. I guess maybe there's a few reasons to extend that out (at least dimly) a bit farther. Wish someone could test that in a video (e.g., haunted house-style situation).

Related article on my blog.

[tetramorph]

rustic313, that is really interesting pointing out encounter distance.

I've been thinking of it more in terms of exploration movement. 60" per move, 120" per turn.

delta, that is some cool research you did there.

What about 30" for torch, 60" for lantern. That would match up the main light sources to move rates.

If I am not surprised by a monster 80" away, maybe it is because I hear and smell it, rather than see it.

[delta]

Or maybe (over 60 feet): Glowing/reflecting eyes, and nothing else, off in the pitch darkness.

[gemini476]

It might be worth pointing out the method implied in both U&WA's "Example of the referee moderating a dungeon expedition" and TSR1's "Solo Dungeon Adventures": you basically just see 10" in corridors (and seemingly infinite in rooms) and react to stuff as you reach them.

Consider the following dialogue:

REF: 10', 20', 30', 40', 50'. "Four way": Northwest, northeast, south and southwest -- the south passage is 20' wide.
CAL: Go south.
REF: 10' -70': passage continues, doors east and west.
CAL: Listen at the east door.
REF: (After appropriate check) You hear shuffling.
CAL: Two of us (specifying which two) will throw out weight against the door to open it. All will be ready for combat.
REF: (After rolling two dice:) The door opens! You can't be surprised, but the monsters -- you see half-a-dozen gnolls -- can be. (Here a check for surprise is made, melee conducted, and so on.)
CAL: Okay, what does the room look like -- we're examining the walls, ceiling, floor, and contents of the room itself.
REF: (After checking to see if dwarves and/or elves are in the party:) The room is a truncated pyramid. The east wall is the truncated part, directly opposite the door you entered. It is 10' long with another door in it. The walls connecting it to the west wall, the place you entered, are each about 35' long. The west wall, which is where you entered is 30' long with a door in the middle of the wall. The elf has noted that there seems to be a hollow spot near the east end of the southeast wall. The floor and ceiling seem to have nothing unusual. The room contains the bodies of the gnolls, a pile of refuse in the north corner of the west wall, and two trunks along the wall opposite the one which sounds hollow.

So we have the referee describing the corridors in that iconic square-by-square fashion, noting doors as they are reached, and conducting room combat before describing the room.

Perhaps the reason that there aren't rules for light source ranges is because they weren't used in that way in the first place? I'm not particularly familiar with the nitty-gritty of the early sessions.
It had certainly changed by the time AD&D came out, in any case. The DMG's monastery adventure has a point where they're told what passages look like "as far out as can be seen", which you'll note that "four way" in the quote up there doesn't. The non-south passages could dead-end within 10ft, for all we know.

I do kind of wish that they had written something about torch/lantern durations, though. I'm pretty sure that the only mention of a torch running out is regarding strong gusts of wind, although you could perhaps make some ruling regarding that 25% chance to drop items when surprised.

[rustic313]

For those that care about a real world analogue, I am preparing a small experiment. I swung by Walmart yesterday and picked up 25, 30, 40, and 60 watt bulbs and two cheap lamps (one with a basic shade reflector desk-lamp style, and one basic table lamp that I can take the shade off for omnidirectional light). I already have a mid-size flame lantern.

To evaluate elvish vision ("see in normal darkness") and other "low light vision," I will use a NVD. I have a Gen 1 nightvision device that I think is a good surrogate for "low light vision"/"starlight vision" (not "infravision," which I envision as a FLIR). I've used Gen 3 NVD before as well but I think it may just be to good for game purposes... with no illumination (IR or otherwise) Gen 3 can easily see hundreds of feet and discern usable detail.

Finally, for the clerical "light" spell (daylight bright) I've got a surefire with a bunch of lumens.

My planned test protocol is to measure the distance at which I can discern:
- Vague outlines/movement of a camouflaged subject. My roan hunting dawg and children dressed in my hunting camoflague will have to suffice.
- A handheld weapon such as a short sword or dagger. My small child wielding his pirate sword should work.
- Detail sufficient to read headlines on a newspaper.

I will evaluate each bulb and the lantern using an omnidirectional lamp as well as a desk lamp with a directional shade. If time allows I'll see how it works with the lamp held in front of me (as if I am carrying it) vs. placed behind me (torch bearer). I will also add the Gen 1 NVD to see what that does for "low light vision."

[delta]

I love this so much. Are you planning your tests inside or outside? I imagine that inside there might be some (maybe slight) extra radiosity effect, compared to outside. Although you'd need a fairly long room to test the questions here.

[scottyg]

Jul 27, 2018 8:14:39 GMT -6 gemini476 said:

It might be worth pointing out the method implied in both U&WA's "Example of the referee moderating a dungeon expedition" and TSR1's "Solo Dungeon Adventures": you basically just see 10" in corridors (and seemingly infinite in rooms) and react to stuff as you reach them.

Consider the following dialogue:

REF: 10', 20', 30', 40', 50'. "Four way": Northwest, northeast, south and southwest -- the south passage is 20' wide.
CAL: Go south.
REF: 10' -70': passage continues, doors east and west.
...

I'm pretty sure that's the DM narrating for the benefit of the mapper, and not an indication of how far the party can see.

[rustic313]

Experiment results (indoors)
Edits in Blue.


Conditions
I set up two different "targets" to look at.  Target #1 was an OD Green jacket against a brown/drab background with a black steel dagger (KABAR sized) tucked alongside the sleeve, semi-concealed.  Target #2 was a kid's book with two different size fonts, one large one and one smaller one, as requested by a previous poster.  The "large font" has letters 3/4" tall and 7/8" wide (54 pitch-ish).  The "small font" has letters 3/8" tall, and fit three letters into every 5/8" (15 pitch). 

I used a basic table lamp (omnidirectional) and a cheap $5 Walmart desk lamp with a simple directional shade that focused the light in a cone +/- 60 degrees-ish.  I also used a Gen 1 NVD (SPARK CORE).  For control, I used my normal house illum plus a Surefire Vampire V1 (250 white light lumens, highly focused).

Data is given in the format of OMNI / SHADED.  Units of measure are paces.  I have a consistent 5 foot pace.  I'd hang my hat on 1 pace = 5 feet +/- 5% having a lot of experience with orienteering, range work and marching.

I evaluated 25W (200 lumen), 40W (450 lumen), and 60W (800 lumen) LED bulbs.   I did not use the oil lamp indoors.  I skipped the 30W bulb, and skipped data collection for the 40W hooded lamp once I saw how consistent the data was.  Additionally, at the end of the test protocol, I had run out of bourbon so that truncated things.  

Luckily, I have a very long central hallway that goes down the middle of a long, skinny house.

Data

Data - 25W Bulb (1" wick oil lamp equivalent)
Large Text - 6.5 / 7.5
Small Text - 2 / 3
Jacket Silhouette - 15 / 16+
Knife Detail - 8 / 9.5
Detail with NVD - 12 / 13

Data - 40W Bulb
(Double wick lamp equivalent)
Large Text - 7 / NA

Small Text - 3 / NA
Jacket Silhoutte - 16 / NA
Knife Detail - 8 or 8.5 / NA
Detail with NVD - 12 / NA


Data - 60W Bulb
("Dressial Belgian" train lantern equivalent)
Large Text - 7.5 / 9
Small Text - 4 / 5
Jacket Silhoutte - 17/ NA
(ran out of space in hallway)
Knife Detail - 9 / 11

Detail with NVD - 13 / 14+

Test Case -- All house lights on plus Surefire white light pointed at target
Large Text - 12
Small Text - 5.5
Knife Detail - 14
Similar data for NVD plus modern IR illuminator only (100W output, highly focused beam) except small text was only about 2 paces

Discussion
I rapidly discovered that holding the lamp in front of me cut vision by about half.  Putting it behind me helped a ton; all the numbers above are with the lamp behind me (i.e. torch bearer mode).   A number of times the extension cord pulled out of the wall.  I'd note that the 60W bulb and to a lesser extent 40W bulb definitely left "stars" in my vision.  The 25W bulb was disorienting to lose the light but not as much as the 60W.

The NVD is fine for reading text but requires mechanical adjustment of the focus for closer-up work.  I just left it on an intermediate focus until it was time to baseline it at the end so focused on discerning the knife detail with the NVD.  I imagine an elvish eyeball has auto-focus adjustment so could rapidly switch from reading words up close to scanning for threats further away.  As a side note, outdoors I have used the NVD with a bright IR illuminator out to 75 yards on man-size silhouettes, and without an illuminator on bright moon-light nights to about 15-25 yards again on silhouttes.

My dog's eyeshine and occasionally a glint off the steel blade showed up great in the NVD, occasionally at significantly longer distances than indicated above.  Less so with the naked eye but occasionally noticeable.

Looking at the quantitative data, the inverse square law is definitely a thing.  For example, take the large text data:  6.5-7-7.5.  You can more than quadruple the lumen output but only get a 15% improvement in detection range.  The same pattern is observed for seeing the knife:  8-8.5-9.

Likewise, the simple hooded lamp seems to give about a 20% improvement in performance.  The biggest benefit was that it was much easier for one person to hold and observe with; holding the hooded lamp in front of you doesn't dazzle your vision like holding an unhooded torch does.

Working indoors did produce some noticeable artifacts; namely, light reflecting off walls, and occasional changes in detail as doorway thresholds were passed.

Conclusions
Something on the order of 80 feet is indeed very realistic for seeing rough outlines, shapes, and eyeshine indoors.  Detail to include small weapons (daggers) and large text is visible at something like half that distance.  Looks like ol' Gary used his experience exploring dark ruins as a kid to good use when coming up with the 2-8" encounter distance rule!

Moving up to a 60W train lantern doesn't help a whole lot.  Even the best case, a hooded 800 lumen train-style lamp, would bump the discernment of details out to about 50 feet, so I imagine silhouettes would be about double that (sorry, I don't have a 100 foot hallway).  At most I think you could justify bumping encounter distance out to 2d6" for such a lamp, and even that is a bit of a stretch.

If you use 1" = 10 feet, then saying that torch/lamp light sheds an 8" circle of shadowy light and a 4" circle of bright light sufficient for seeing detail is a wonderful approximation.

Lastly, "low light" elvish vision (i.e. NVDs) is definitely a perk.  It bumps detection of details (the knife, in this case) out to about 75% of the illumination distance for a high probability of detect, rather than being limitd to around 50%.  Additionally, the "control" case with full illum could see the knife at 14 paces.  The NVDs spotted the knife at 12-14 depending on scenario, making the NVDs almost as good as "full daylight vision" at detecting the detail.  I would highlight that the Gen 1 NVD got intermittent detects of the knife out to longer distances depending on glint, reflection, eyeshine, etc.  For the sake of simplicity I think it is very reasonable to simply say that elves at al can observe detail out to the full radius of shadowy light (whereas poor Humans just see shadows, shapes and movement), but not necessarily a significantly longer detect range at all.  I'll have more data on that once I go outside on another night.

Final thought on scale:  I have been using 1" = 5', 1 round = 10 seconds for some time as suggested by Delta.  However, I am seriously considering going back to 1" = 10', 1 round = 20 seconds.  There are now a lot of 15mm fantasy miniatures available that facilitate working at that scale.  The light numbers here just mesh so perfectly with a 1" = 10' scale, and for a game where underworld exploration is so key that is a major factor.