Years ago I did some spelunking in a handful of remote caves. Most of my companions used carbide head lamps - not too bright but reliable. I used a 6-volt electric lamp that used odd batteries that I've only seen in outdoor stores. On one trip to a cave in Nevada my headlamp was initially brighter than the carbide lamps but when the battery began losing power and it became dimmer than the carbide lamps my companions all told me I should change the battery. I was determined to get all the life out of the expensive batteries that I could so I ignored them and kept going with my ever dimmer light. I noticed that even when my light was very feeble I could still see just fine. In fact, I could see detail better with my very dim light than I could when I looked at surfaces illuminated by my friends' lights. I think that in addition to the issue of what works better for dark-adapted vision there is also a contrast issue. For awhile after I purchased my Ultima 2000 I tried using my computer and a cheap program, SkyMap Pro, to drive it. The red light setting on the program was still much too bright. I picked up some scrap red Plexiglas from Delvie's in SLC (very cheap) and cut it to fit over my laptop monitor, fixed in place with a couple of pieces of Velcro. That cut the brightness enough that it didn't affect my night vision anymore than a dim red flashlight. I recommend it for anyone who uses a computer at night, even in red mode. Kim