I'm just pointing out that there a lot of questions are about how many lumens are brighter, etc..and, you can't SEE lumens...its the wrong unit.
Essentially, lumens are what are sent out...but the intensity of the dot is a function of the light that bounces back to your eyes.
THAT is measured as lux typically.
As the human eye is a LOUSY light meter, we're terrible at judging how bright a dot of light is.
There are devices that can measure lux (lux meters), but you'd need to get one that will read a laser accurately.
The other issue to consider is that lux is lumens per square meter.
So if you know the lumens, the cd, and the size of the dot, you can calculate the lux...but you won't.
The useful part revolves more around the idea that if you have the same sized dot, and, get it with more lumens in the same surface area....doubling the lumens doubles the lux...its a one to one ratio if the dot size is constant.
When you add in what nm, you run into yet another issue...Lumens (And therefore lux) are weighted by the eye's response to various nm ranges...so some wavelengths "count more or less than others".
So, if you use a lightly weighted wavelength, a measured lux would be low, etc.
As discussed, when completely night adapted for example, you are essentially seeing in black and white anyway. The less adapted you are, the more color you might be able to distinguish.
Its all a question of degree after that.
Some people will see red better than others for example, and, that will impact their perception of that nm range, and so forth.
