The total brightness measurements of the underwater lights shown on this site are given in lumens. The definition of the lumen is based upon the sensitivity of the human eye, and is the best measure of how well a light can illuminate a given area. Lumen measurements take into account the total amount of light produced by the fixture, regardless of whether it is focused into a narrow beam or spread across a wide area. Lumens are a much better measurement to use than watts, which are a measure of electrical power, because different kinds of lights produce more or less lumens for a given amount of electricity. For example, a typical 55 watt halogen light produces about 600 lumens of light. An LED fixture that produces 600 lumens will typically only use about 10 watts of electricity.
The underwater light brightness and electrical tests shown on this site are performed in a state-of-the-art optical laboratory using properly calibrated instruments. The measurements are done in accordance with procedures developed by the Illuminating Engineering Society of North America (the IES). Specifically, the 2 Pi procedure of IES Method LM-79-08. The equipment used is a 1 meter LabSphere Illumia integrating sphere with a CDS-610 spectrophotometer. The sphere is calibrated weekly against a NIST traceable calibration lamp. Simultaneous electrical and thermal measurements are made with calibrated, high accuracy laboratory instruments.
The one deviation from LM-79 that is made for the testing that is presented on this site is the thermal stabilization time. Since underwater lights are intended to be operated submerged, they are normally cooled by the surrounding water. The LM-79 method, which is intended for testing lights in air, requires that the lights be operated for long enough that they reach a steady operating temperature. Underwater lights, operated in air, would become so hot after an extended period that they would not produce their normal, full output. Most high-quality underwater lights are equipped with special circuitry to reduce the light output or shut down completely to avoid burning up when operated out of the water. In order to present an accurate representation of the actual underwater lumen output of the tested lights, and to be fair to all manufacturers, the lumen measurements are made one minute after the lights are turned on (in air), after stabilizing (powered off) at an ambient temperature of 25 degrees Celsius ( 77 F).
All photos have been taken in the same conditions using the same equipment, to insure accuracy and consistency. Below are some more details:
Camera: Nikon D7100
Lens: Nikon DX SWM VR ED IF Aspherical ø72
Shutter speed: 1/20 S
F Stop: 10
Light distance to wall: 1 meter
Camera Distance to wall: 2 meters
All prices are taken from the average market price at time of purchase.
Date of purchase for each light varies, as detailed below:
All testing was done in Lumitec’s in-house optics lab. Lumens were measured using a Labsphere integrating sphere, taken at 1 minute after startup.