The ARRI Photometric Calculator is designed to demonstrate the photometric performance of ARRI lampheads at different lamphead setups and distances. It also helps to get an idea of the correct camera setup. Its design and usability are optimized for smart phones with touch screen. Usability is best when the phone is in portrait mode and the web site is scaled to this mode (via double click).
Choose your desired ARRI product.
Select category first, then continue with product group. The last dropdown finally selects your lamphead.
Configure the selected lamphead according to your needs. Different configuration possibilities exist for different technologies.
A click on the underlined product name brings you to the product home page.
The actual photometric measurements are displayed in this section. Choose the desired metric system using the radio buttons. You can switch at any time.
Use the sliders or enter values directly into the corresponding text boxes to select your target values. The other values and sliders change and display results accordingly.
Please note: Distance can be selected in between 0.5m and a viable maximum value defined for each lamphead. How ever, depending on light intensity there is a minimum safety distance defined individually for every lamphead. The distance slide turns red when a distance below safety is selected.
The beam angle is a constant value and therefore does not change.
For most lampheads, a light distribution graph is available. It can be viewed by clicking on the “Light distribution” symbol in the lower right corner of the measurements section. The graph shows the luminious intensity in one plane across the beam diameter, where 0° is the optical axis. Please note that the unit is candela and not lux, and therefore values are valid for a circular path around the lamphead, not for a distribution on an even wall. Generally, a smoother graph indicates a higher quality of the light field.
Get an idea of the correct aperture your camera requires in order to reach a correct exposition.
Select your camera setup by defining film exposure index, shutter angle and camera speed. If a filter or other light consuming accessories are used, select a value between 1% and 100% in the filter factor box.
Please note that this is just an approximation assuming that the frame is filled with a simple 18% grey. Correct exposure may vary due to frame content and desired look.
If changing a value via the interface does not result in a prompt change in the output values, please use the “calculate” button in the lower right corner.