The elf, and half-elf low-light vision extends 60' as well. but again, Dark-Vision is, essencially infra-red sight. They see into the lower light spectrum and heat rather than light. A torch or latern produces heat, so that heat effects their sight. It's something like looking past a 100 watt light bulb when the bulb is either right in front of you, or next to your head. It's difficult (if not impossible) to see through the source of the light. Seeing into a second level of light at the same time means that the dwarf has to have two sets of eyes. You can, as an example, cover one eye with your cupped hand and turn out the light. The covered eye has adapted to the difference in light, so you have partial night sight for a few moments while the other eye catches up... it also tends to give you a mild headache for a second or two if you do it too much.<br/><br/>Even the world's most famous night vision animal, the cat, is night blind when it's standing in a room with a light source and looking out into the dark via a window. Science has proven this facet. The Human eye (and the real difference between elven and human eyes (and dwarven) is the number of rods and cones, not a mystical magical ability) cannot see both in darkness and light at the same time. The iris allows in either more or less light depending on the level of light provided. Low-light means that the ratio between rods and cones in the eye is different and can therefore interpret more of the light spectrum, but it's still restricted to one form or the other at any given moment.<br/><br/>I would say, in the absence of a written statement in any of the source material, that it's a GM's call. but it doesn't make sense for someone to see normally in a light for 20 feet, then see in the infrared or in a different spectrum beyond that. That would negate the -2 attack penalty for the drow's vision simply by giving them a ranged weapon and saying, "Just shoot into the dark areas... you can ignore your penalty since you're not actually "looking" in the light.