Vision and Light
Before a character can do anything in the dungeon or the wilderness, he has to be able to see what he is doing. If a character can't see a target, his chances of hitting it are very small. If he can't see, he can't read a scroll or a large "Keep Out" sign on the wall. In the AD&D game, characters can see set distances and often by fantastic means that defy logic.
Limits of Vision
The first limitation on vision is how far away an object can be before it cannot be seen clearly. Size and weather have a great effect on this. Mountains can be seen from great distances, 60 to 100 miles or more, yet virtually no detail can be seen. On level ground, the horizon is about five to 12 miles away, but a character usually cannot see a specific object that far away. The limit of vision for seeing and identifying man-sized objects is much less than this.
Under optimum conditions, the maximum range at which a man-sized object can be seen is about 1,500 yards, if it is moving. If the object doesn't move, it usually cannot be seen at this distance. Even if it is moving, all that can be seen is a moving object. The character cannot tell what it is or what it is doing.
At 1,000 yards, both moving and stationary man-sized objects can be spotted. General size and shape can be determined, but exact identifications are impossible. It is not likely that creature type can be identified at this range, unless the creature has a very unique shape.
At 500 yards, general identifications can be made. Size, shape, color, and creature type are all distinguishable. Individuals still cannot be identified, unless they are distinctively dressed or separated from the rest of the group. Livery and heraldic symbols or banners can be seen if large and bold. Most coats of arms cannot be distinguished at this distance. General actions can be ascertained with confidence.
At 100 yards, individuals can be identified (unless, of course, their features are concealed). Coats of arms are clear. Most actions are easily seen, although small events are unclear.
At 10 yards, all details but the smallest are clear. Emotions and actions are easily seen, including such small actions as pick-pocketing (if it is detectable).
Of course, conditions are seldom perfect. There are a number of factors that can reduce visibility and alter the ranges at which things can be spotted and identified. The table below lists the effects of different types of conditions.
All ranges are given in yards.
"Movement" indicates the maximum distance at which a moving figure can be seen. "Spotted" is the maximum distance a moving or a stationary figure can be seen. "Type" gives the maximum distance at which the general details of a figure can be seen--species or race, weapons, etc. "ID" range enables exact (or reasonably exact) identification. "Detail" range means small actions can be seen clearly.
There are many factors other than weather that affect viewing. Size is an important factor. When looking at a small creature (size S), all categories are reduced to the next lower category (except the "detail" range, which remains unchanged). Thus, under clear conditions, the ranges for seeing a small creature are "movement" at 1,000 yards, "spotted" at 500 yards, "type" at 100 yards, and "ID" and "detail" at 10 yards.
When sighting large creatures, the "movement," "spotting," and "type" ranges are doubled. Exceptionally large creatures can be seen from even greater distances. Large groups of moving creatures can be seen at great distances. Thus, it is easy to see a herd of buffalo or an army on the march.
The ranges given in the table below do not take terrain into account. All ranges are based on flat, open ground. Hills, mountains, tall grass, and dense woods all drastically reduce the chances of seeing a creature. (The terrain does not alter sighting ranges, only the chances of seeing a creature.) Thus, even though on a clear day woods may hide a bear until he is 30 yards away, it is still a clear day for visibility. The bear, once seen, can be quickly and easily identified as a bear. The DM has more information on specific terrain effects on sighting.
Visibility Ranges
| Condition | Movement | Spotted | Type | ID | Detail |
|---|---|---|---|---|---|
| Clear sky | 1,500 | 1,000 | 500 | 100 | 10 |
| Fog, dense or blizzard | 10 | 10 | 5 | 5 | 3 |
| Fog, light or snow | 500 | 200 | 100 | 30 | 10 |
| Fog, moderate | 100 | 50 | 25 | 15 | 10 |
| Mist or light rain | 1,000 | 500 | 250 | 30 | 10 |
| Night, full moon | 100 | 50 | 30 | 10 | 5 |
| Night, no moon | 50 | 20 | 10 | 5 | 3 |
| Twilight | 500 | 300 | 150 | 30 | 10 |
As a final caveat, the ranges in the table above assume Earthlike conditions. Sighting conditions on one of the Lower Planes, or the horizon distance on another world, could be entirely different. If your DM feels he must take this into account, he will have to learn more about this subject at his local library or make it up.
Light
Most characters cannot see much without light. Some night conditions (those for the outdoors) are given in the Visibility Ranges table above. But all of these assume some small amount of light. In totally lightless conditions, normal vision is impossible, unless a source of light is carried by the party.
Light sources vary in the area they affect. The table below gives the radius of light and burning time for the most common types of light sources.
Light Sources
| Source | Radius | Burning time |
|---|---|---|
| Candle | 5 ft | 10 min/inch |
| Torch | 15 ft | 30 min |
| Hooded lantern | 30 ft | 2 hrs/pint of oil |
| Beacon lantern | 240 ft* | 30 hrs/pint of oil |
| Bullseye lantern | 60 ft* | 2 hrs/pint of oil |
| Campfire | 35 ft | 1 hr/armload of wood |
| Bonfire | 50 ft | 1/2 hr/armload of wood |
| Light spell | 20 ft | Variable |
| Continual light | 60 ft | Indefinite |
| Weapon** | 5 ft | As desired |
* Light from these is not cast in a radius, but rather in a cone-shaped beam. At its far end, the cone of light from a beacon lantern is 90 feet wide. A bullseye lantern has a beam 20 feet wide at its far end.
** Magical weapons usually shed light. Some shed light only in the presence of certain creatures.
Of course, while a lantern or fire enables characters to see, it does have some disadvantages. The greatest of these is that it is hard to sneak up on someone if he can see you coming. It is hard to remain inconspicuous when you have the only campfire on the plain, or you are carrying the only torch in the dungeon. Furthermore, not only do creatures know you are coming, they can generally see you before you see them (since the light source illuminates the area around you, those outside this area can see into the area). Characters should always bear these risks in mind.
Infravision
Infravision is the ability to sense or "see" heat. You may have seen an exhibit in a Science Museum where you can see yourself in the eye of an infrared camera. It looks like the picture to the right.
This special sense is limited to a 60-foot range. Within this range, characters can see the degrees of heat radiated by an object as a glowing blob translated into colors like a thermagram.
There are several things that must be considered:
First, large heat sources will temporarily blind characters with infravision just as looking at a bright light blinds those with normal vision. Thus, those attempting to use infravision must make the effort to avoid looking directly at fires or torches, either their own or the enemy's. (The light from magical items does not radiate significant heat.)
Infravision cannont distinguish one humanoid type from another of a similar size, and certainly cannot let people be "recognized" at any distance of more than 5 feet.
Vague outlines of doors can be discerned.
Ultravision
Despite its scientific inaccuracy, for game purposes, ultravision is the term used to describe the ability to see at night. It could be considered to be like having passive night vision goggles, which amplify ambient light, similar to the picture at the right. 
In night conditions this means that vision will be clear, as if it were daylight, to a range of 100 yards, and shadowy and indistinct from beyond 100 yards to about 300 yards distance. If the night is very dark, with thick clouds overhead, reduction of ultravisual sight is 50%.
Where more than about 6 feet of earth or 3 feet of stone interpose between the sky and the individual, such as in virtually any underground area, ultravision allows only vision of the dimmest sort in about 3-foot radius, since the ultraviolet rays are screened out. (Of course, if an emission source is nearby, the visual capabilities improve accordingly.) Nearby light, including the radiance shed by magic items, tends to spoil ultravision, the brightness of the rays “blinding” the eyes to dimmer areas more distant.
Using Mirrors
At times it is useful for characters to look at objects or creatures via reflections in a mirror. This is particularly true of those creatures so hideous (such as a medusa) that gazing directly upon them might turn the viewer to stone. When using a mirror, a light source must be present. Second, attempting to direct your actions by looking in a mirror is very disorienting (try it and see). Thus, all actions requiring an ability or proficiency check or an attack roll suffer a -3 penalty. The character also loses all Dexterity bonuses to Armor Class if fighting an opponent seen only in a mirror.