Visibility and Illumination

I've been trying to lock down some concrete rules on visibility for Dungeon Crawl Classics since the rulebook doesn't give specific details on illumination or vision, it's one of those things it leaves open for the GM to determine on his own. All of this speculating was prompted by my desire to convert some 1st edition AD&D modules into Dungeon Crawl Classics adventures, and I really wanted to clearly outline for my players what their visibility would be in these dungeons. I also recently started reading Untimately, and the thoroughly analytical approach Brendan has toward the original D&D books inspired me to look at every edition of D&D in a similar way, just like I did that one time when I made the same character in every edition of Dungeons & Dragons.

Let's start with 1st edition AD&D. The Dungeon Master's Guide gives no real limitations to vision and in fact says line of sight could potentially be "infinite" (p.62) but has paragraphs for arbitrating Infravision and Ultravision abilities. I'm mostly interested in regular old line of sight for the average human and how it relates to dungeon delving. The 1st edition Player's Handbook has a table (p.102) that lists light sources:
Torch, 40 feet
Lantern, 30 feet
Bullseye Lantern, 80 feet

Quick Footnote: It's interesting to note that the same table lists magic daggers and swords as light sources. Torches and lanterns also have "burning time" listed, as presumably the DM was meant to keep track of how long the PCs had been using the same light source. This effectively meant that a ring with a light spell was once considered an invaluable piece of magical equipment!

2nd edition AD&D does a little bit of clarifying line of sight. In the Player's Handbook (p.117) it gives definitive distances in yards for what can be seen depending on the weather. Each column is delineated by the distance at which a man-sized object can be seen moving, spotted (for stationary creatures and objects), general identification, clear identification, and detailed identification. This is an interesting, if exhaustive, breakdown because the table also includes worst possible conditions such as "Night, no moon" and "Fog, dense or blizzard."

The 2nd edition light source table lists a few immediately noticeable differences right away:
Torch, 15 feet
Hooded Lantern, 30 feet
Bullseye Lantern, 60 feet
Something I never really registered before, or maybe I just ignored back when I played as a teenager, is that these light sources also have burning times listed, and each one seems different than it's 1st edition predecessor. The burn times become more consumptive and restrictive in 2nd edition, and I would infer that because of this both players and DMs alike were less inclined to pay attention to such details. The 2nd edition trend of having adventures that didn't take place in dungeons probably helped the eventual disuse of these details. Also, Magical weapons still shed light, but it clearly states this is an optional rule that a DM may not allow.

The 3rd edition Player's Handbook has it's own table of light source visibility and burn times (p.165) and this table shows a reversal of the 2nd edition numbers. Instead of sharing these numbers, let's just do a quick comparison of all of the different editions, including their burn times:

	1st edition	2nd edition	3rd edition
Torch	40 feet / 1 hour	15 feet / 30 minutes	40 feet / 1 hour
Hooded Lantern	30 feet / 4 hours	30 feet / 2 hours	60 feet / 6 hours
Bullseye Lantern	80 feet / 4 hours	60 feet / 2 hours	120 feet / 6 hours

Strangely, 3rd edition gives illumination figures for use in areas of bright light, which seems redundant to me and I'm at a loss for why that column is listed at all. Check it out for yourself, the explanation is on page 164.

It's worth noting that 4th edition lists illumination in squares, but doesn't ever list how many feet or yards a single square is.

I think the 1st edition AD&D numbers are solid, and I'm perplexed as to why they were ever changed in later editions.