Re: The Real Reason for Throw-an in depth examination
The reflective nature of the object of interest is not always the same and this too comes into play. Reflective street signs can light up at hundreds of yards being illuminated by a weak flood source that can't reveal a skunk at 50'.
It seems that the idea of throw if not its definition has been well fleshed out here by the group of contributors. The OP's concern that folks equate the measure of lumens to a lights ability to "throw" will continue to be a source of confusion for anyone not understanding the various measures of light output or more specifically, the difference between lux and flux.
If there were an instrument like a spotter's scope that were to measure the return light from a distant object, this might well be the tool to use to measure effective throw. A lux meter placed behind a scope as it were.
One could place a lux meter on a standardized target and then back away from this target while illuminating it until the threshold was reached for the individual at which point they felt they could no longer discern the target. The measure of lux (now measured at the target) at this distance could then be established for the individual as being the minimum for this specific target. They could then repeat the process with other light sources and get a feel for the various throws of these lights. It would also be illuminating to see how and if the minimum lux necessary for this target were to vary because of the spectral nature of the light source itself.
I am still confused by the actual title of this thread. I would submit that the real reason for throw is simply that there are times when a person needs to be able to effectively illuminate a distant target and for that purpose needs a light that can provide adequate throw.
Clearly different lights will have various abilities to throw light and illuminate targets at any distance. Their success is so subjective in nature and dependent on both the observer as well as the nature of the target that it is unrealistic to hope for some simple and objective measure of throw.
The reflective nature of the object of interest is not always the same and this too comes into play. Reflective street signs can light up at hundreds of yards being illuminated by a weak flood source that can't reveal a skunk at 50'.
It seems that the idea of throw if not its definition has been well fleshed out here by the group of contributors. The OP's concern that folks equate the measure of lumens to a lights ability to "throw" will continue to be a source of confusion for anyone not understanding the various measures of light output or more specifically, the difference between lux and flux.
If there were an instrument like a spotter's scope that were to measure the return light from a distant object, this might well be the tool to use to measure effective throw. A lux meter placed behind a scope as it were.
One could place a lux meter on a standardized target and then back away from this target while illuminating it until the threshold was reached for the individual at which point they felt they could no longer discern the target. The measure of lux (now measured at the target) at this distance could then be established for the individual as being the minimum for this specific target. They could then repeat the process with other light sources and get a feel for the various throws of these lights. It would also be illuminating to see how and if the minimum lux necessary for this target were to vary because of the spectral nature of the light source itself.
I am still confused by the actual title of this thread. I would submit that the real reason for throw is simply that there are times when a person needs to be able to effectively illuminate a distant target and for that purpose needs a light that can provide adequate throw.
Clearly different lights will have various abilities to throw light and illuminate targets at any distance. Their success is so subjective in nature and dependent on both the observer as well as the nature of the target that it is unrealistic to hope for some simple and objective measure of throw.