OK I think I finally understand the deal with night vision, the second link I posted above is very informative. Again, whats most important as far as preserving night vision is using as little light as possible. Apparently there was a scientific study with thousands of subjects that found that our the cones in our eyes are most sensitive to light at 555 nanometers(nm) in the electromagnetic spectrum, and the rods are most sensitive to light at 510 nm. Cones detect color light and rods detect black and white light, and its the rods that we use most when its dark and our eyes are adapted. According to the technical specs section of the photon webpage, the turquoise photon emits light at a wavelength of 495 nm, which is very close to 510 nm, so are eyes are more sensitive to that color than any other when our eyes are night adapted. Because our eyes are most sensitive to that color light, a light with less brightness can be used, therefore not affecting your night vision as much. If you use a red light, you will need it to be much brighter because your eyes are much less sensitive to that color.
However this is only releveant if you use a very dim light. If your light is too bright, then it will ruin your night vision regardless of the color. Remember these experiments were done using very low levels of light. The ideal light would have just barely enought to see by. this amount of light will vary greatly depending on what your are doing. If you are an astronomer and just need a light to read a star chart by(much information about night vision comes from astronomers who need to read star charts and still preserve night vision to see faint stars at night), then you will need a very faint light. Even the little green LED on my keyboard that tells you when the caps lock button is pressed might be too bright for this, and a photon would be out of the question. On the other hand if you need a light to walk around with could be brighter, but the amount of light would depend on wether you are outside or indoors, where walls, the ceiling, furniture and other objects reflect the light and therefore you need much less. According to the website where I got much of this information from, if you can see color, then your night vision has beem compromised. Lets face it you're never going to get a level of light that low, and even if you could it wouldn't be very useful. The best you could hope for is to affect it as little as possible.
Ok I've just spent a lot of time explaning night vision, now here are my recomendations: First of all, most of the time theres no point in worrying about night vision at all. If you care so much about your hard earned night vision, don't use a flashlight at all! If you're eyes really are fully adjusted to the dark, then you should have no problem walking around a dark room or anywhere outside. If you can't see clearly enough to walk around at a medium pace without bumping into a tree branch or something or tripping over an obstacle, then your eyes probably aren't fully adjusted.
In order for your eyes to be fully adjusted to the dark, you need in a dark environment for more than an hour with no sources of light pollution such as a streatlamp. There are different levels of darkness and if you go from one dark area to a darker one, say from an unlit room at night with windows to your unlit basement, you will have to get adjusted to that environment as well.
If your eyes aren't fully adjusted to the dark, then thats what a flashlight is there for. Who gives a crap about your night vision, since you don't have it anyway, and if you have a flashlight you don't need it!
The only time you would really need aditional light to see when your eyes are fully adjusted would be if you're in a sealed building with no windows, a deep cave or someplace underground, or if you need to read something or something else recqiring more detail.
In this situation, when you need a bit more light but you don't want to completely ruin your night vision, i think you're best bet would be to take a turquoise Photon 3 and keep it set on the lowest level. Even better, replace the 2 CR-2016 batteries with 1 CR-2032 battery to make it even dimmer. I haven't done this yet so I don't know how bright this will be, but you'll probaby want to keep it the low or medium settings, and this way you can adjust it depending on how dark adapted your eyes are and how much ambient light there already is. Since all Photon 3s have the same body and a CR-2016 is exactly half the size of a CR-2032, this shouldn't damage the photon at all and will in fact make the batteries last much longer. This will still damage you're night vision somewhat but not nearly as much as a brighter light. Just be careful not to accidentally push button on the front, even a second of the bright light will ruin your night vision instantly.
Anyway I've been talking for a while and if you've actually read everything I said thank you for not making that a waste of time. I am by no means an expert and I'm making no guarantees about anything I've said, and I may very well be wrong about some of them. The above is pretty much just a compilation of ideas I've seen along with my own conclusions and suggestions. Anyone who know anything about the subject by all means say something. I hope this helps.
