My L6 de-domed XP-G2 does 439Kcd (1325M throw), simply won’t reach a mile. The L2 with XHP-35 makes 332Kcd (1152M throw) , again, just not putting anything out there at a mile to see by.
Light travels in an exponential manner, it takes 4 times the light to travel twice the distance. Numbers get thrown around a lot in the forums, but achieving in excess of 600Kcd is just not easy. Wouldn’t surprise me if my 3 watt blue laser would’t reach a mile. Yet my 200mW green one easily does twice that, virtually all about the spectrum and the power it takes to push it.
Giving a quarter lux at a given distance, or the equivalent of a full moon, is difficult to read anything unless it’s in your hand. Looking back at a light source one can see the source from much further out than said source can lay down visible light. A reflector will light up far beyond where you can tell there’s light being made, for example, which is why people should remember to dim their high beams when driving… while the light being made doesn’t seem to reach far, it can cause the oncoming driver to lose night vision and quite possibly run into the one that failed to dim… just sayin. Everyone’s eyes are different of course, and while 90% of the folks here might call BS on what I just said, my daughter’s eyes are hypersensitive at night and she can be night blinded from quite a distance away. Many women suffer this phenomenon. My daughter says an oncoming cars lights pierce her eyes like needles, causing physical pain and making her look away. Obviously potentially dangerous.
My point here is this… tonight if my wife looks at the TN42 at a mile off her eyes won’t be able to see the paper illuminated as well as if she refuses to look at the light directly. At a mere 1/4 lux, the sheet of paper won’t be lit up brightly and will be difficult enough to get a good picture of. I’m planning on using my normal beamshot settings of ISO 1600 , f/5.6, 1/2 sec shutter. I haven’t done anything like this before so I’m not exactly sure what settings to use. I know if it were me on the target end with my main Canon camera I could use settings to make it look like daylight, but of course that’s not the point is it? Imitating what the eye is seeing, that’s the objective. So I’m fairly certain the first attempt will be bogus, would almost bet money my wife will somehow get the camera settings wrong. To that end, I’m debating switching ends with her, let her turn the flashlight on and point it at me, but that brings a whole new set of alignment issues into play.
This just isn’t as easy as it might would seem.
Granted, we are “only” a mile apart, across the lake. But the marina my wife will be at is in a small community, it’ll take some 10-15 minutes to drive between the two spots. The place I will be stationed is a pretty much abandoned loading ramp and dock, trashy, difficult to access, and with a less than desirable public that uses it more for drinking and what not than fishing or boat launching. So it’s got to be me at this site, my wife at the nicer marina. But there are some parking lot lights at the marina, she’ll have to traverse some rocky lakeshore area to get away from the lights, it’s gonna be somewhat tricky. All’s we can do is try, right? (while watching out for critturs, both creepy crawly kind and vertical ones)