How does Incident Light Metering work

following on from an earlier post I have a similar question about light metering.

I understand the basics that Incident measures the light falling on the subject whereas reflective measures light reflected from the subject.

Reflective makes sense because the sensor is some distant from the subject and receives light reflected of the subject and therefore it makes sense that exposure is adjusted to ensure the sensor/film receives sufficient light to create a properly exposed image.

However I don't see how incident light reading can easily be converted into an exposure setting as it measuring the light at the subject and therefore ignores the distance to the sensor/film/camera etc. although it is clear that the amount of light reaching the subject will be reflecting a certain amount (in different directions) back towards the camera. Surely only the light being reflected back towards the camera is what will affect the exposure requirement so how does the light meter manage to evaluate the light correctly to obtain the exposure setting. I have always understood that the further away from an object the light is dimmer due to it being spread over larger area (hence the inverse square law) so if you measure the incident light and get an exposure reading what happens if the distance to the camera is doubled, the light meter will still give the same setting but the theory says you need to increase the exposure because of distance....I have probably got confused because I am missing something vital from these techniques so it would be appreciated if someone could enlighten me on how incident light metering actually works and is often the preferred method when in studio or using flashmeters.

TIA

What you have confused is that there is NO change in exposure settings based on the distance from a subject. Think about it for a moment. If you look at a building and then back up a mile or two, does the apparent brightness of the building change? No, it does not.

The inverse square law is really concerned with a point source of light and how much of the light from that source falls on something at various distances from that light.

SkipD wrote in post #15137416
The inverse square law is really concerned with a point source of light and how much of the light from that source falls on something at various distances from that light.

Dead right, and the inverse square law follows from a geometric argument about the photons fanning out from the source. When they are not fanning out, e.g. from a laser, there is no inverse-square falloff. This is how laser pointers work; only relatively few photons are scattered, by collisions with floating particles (dust).

melcat wrote in post #15137473
Dead right, and the inverse square law follows from a geometric argument about the photons fanning out from the source. When they are not fanning out, e.g. from a laser, there is no inverse-square falloff. This is how laser pointers work; only relatively few photons are scattered, by collisions with floating particles (dust).

Yeah, fall-off only concerns the source, not how it's perceived. Lasers are different because of a phenomenon in physics where photons cause other particles they pass by to release photons as well, even the same particle that emitted the photon in the first place, assuming you apply a constant charge. The density of photons in a laser is so high, that distance is hardly a limiting factor... Even so, laser light does have to be focused and it does spread out over a distance, so by the time the light from your laser pen reaches the moon, it's likely to cover the whole surface area of the moon, so don't worry about blinding any astronauts.

Anyways, incident light metering does work because whether your subject is pure white or black, the meter only cares about how much light is going hit the subject. Reflective metering attempts to equalize all tones within the image to a reference shade (18% gray), which means that if you're at a wedding shooting the bride and groom, a reflective meter will want the white dress or black suit to be the reference shade, under-exposing the former, and over-exposing the latter. This is why cameras use sophisticated metering algorithms to attempt to guess what you're photographing.
If you go out to photograph in winter with full snow out, you'll find your camera often severely under-exposing, even with +ev adjustments.