Comparing LED Flashlight to Sunlight

[loomdrop]

If you had a typical LED flashlight that requires 4 AA batteries shine on you close up (1 inch away) for several minutes, would that be more visible light than you'd get from an hour or two standing in summer sunlight (visible light not UV or infrared)? What about if the flashlight was on for 9 minutes? Would it start to be hot?
I am interested in the comparison between an LED flashlight close in proximity and natural sunlight since most of sunlight is in the visible spectrum.
Also, I read that LED flashlights are either typically made from blue light and have a phosphorus add on to make white or are made with multiple LEDs to make white. For the blue light/phosphorus method, does that mean that the original blue wavelengths all end up becoming longer and losing power/heat? Lastly, Does anyone know how LED flashlights with adjustable focus and different options of brightness for high and low are made or what category that would fall into?

 

[jon_slider]

loomdrop, welcome
You may find this Flashlight Wiki informative as a starting point

 

[parang]

Sunlight at noon is about 10k lumens, IIRC.

 

[letschat7]

For what it is worth Led Lenser makes some adjustable lights.

 

[defloyd77]

To help us help you, do you have a particular use in mind, like treatment for SAD or is this just out of curiosity?

 

[alpg88]

measure it. use photo exposure meter,

 

[desert.snake]

If you had a typical LED flashlight that requires 4 AA batteries shine on you close up (1 inch away) for several minutes, would that be more visible light than you'd get from an hour or two standing in summer sunlight (visible light not UV or infrared)? What about if the flashlight was on for 9 minutes? Would it start to be hot?
I am interested in the comparison between an LED flashlight close in proximity and natural sunlight since most of sunlight is in the visible spectrum.
Also, I read that LED flashlights are either typically made from blue light and have a phosphorus add on to make white or are made with multiple LEDs to make white. For the blue light/phosphorus method, does that mean that the original blue wavelengths all end up becoming longer and losing power/heat? Lastly, Does anyone know how LED flashlights with adjustable focus and different options of brightness for high and low are made or what category that would fall into?

Oh, this is all very, very difficult. You will need to find out what spectrum and power the LEDs you are interested in have and compare the power distribution and power with sunlight at your location at a certain time of day. Good measuring devices aren't cheap either

6.4 The Solar Spectrum | METEO 300: Fundamentals of Atmospheric Science

Spectral power distribution - Wikipedia

en.wikipedia.org

In short - regular 4AA LED flashlight will not be able to heat your hand even if you illuminate it for a whole year, there is too little energy. Although even this is enough to destroy the retina if you shine the light deliberately into the eyes for a long time, not allowing you to look away and close your eyelids