Here is a concrete example of what I am talking about. You don't have to buy an Acebeam K70 to carry out this experiment, but it will be more fun if you do!
So get your light set up for throw, and wander down field with your favorite book on the physics of light. Have an assistant sit with the flashlight, and turn it on and off as you move away. Use a cell phone to coordinate with your assistant.
Find the shortest distance at which there is not enough light to read by. With the K70, that should be about 1300 meters! When you do this, hold the book exactly perpendicular to the flashlight beam. Now, take a couple of steps back towards to the light. Move just enough so that you can read, and no more.
Okay, you have found the lowest lux at which you can read. Now tilt the book back 60 degrees. As the cosine of 60 degrees is 1/2, this will cut the lux in half. Voilà! You can no longer read. Even though you are still the same 1300 meters away from your K70 flashlight, the lux on target has changed.
This is proof that the lux on target depends on the angle at which your flashlight beam strikes the target.
I understand what you are saying, but, lux is what bounces back to your eyes....the lumens per square meter.
If the surface is angled, less is reflected back to your eyes, so the flashlight sent out the same amount and quality of light, but, essentially, less was reflected back to you.
If comparing lights, the differences in how far you can see, at the maximum range, will therefore be proportional to the beam's cd.
This THREAD is to explain the difference between lux and lumens...and to allow readers to gain a feel for what they represent.
If we go off on tangents (pun intended), we dilute the light we are trying to cast on the subject.