If you are used to lighting with regular tungsten hot lights, the brightness information on an LED light's product description will surely sound vague and confusing. In this video you will find out how an LED lights' brightness compares to a regular 1-kilowatt tungsten hot light.
For those who are new to using the "stop" terminology, this means twice or half the amount of light. A stop more light means two times more light than we currently have, while a stop less is half the light we've got. In this video you will see that certain LED lights are measured at "minus two stops," which means they are four times less bright than the standard used in the video, the 1 kW (or 1K) hot light. That "minus two stops" LED light will have a comparable intensity to a 250-watt hot light.
The guys from The Slanted Lens set up a fair test environment where the 1K tungsten is set to flood mode (not focused) and blast light towards a light meter. A number of LED lights take the spot of the tungsten and their intensity is also measured. The results indicate how many stops under or over the LED lights differ from the tungsten.
A good thing to remember is that a regular 1K tungsten light is measured at f/8.7 at a distance of 8 feet with the camera set at ISO 800 and 1/50 s for the shutter speed. Most of the affordable LED panels that were tested were measured at about two stops under than the tungsten light, meaning four times less powerful. Most fresnel LED lights they tested, however, had a similar light output to the 1K hot light.
We hope you found that comparison helpful. Let us know if you have impressions from LED panels or more focused LED sources that were not tested in this video.