I have a few corporate clients that hire me to photograph their events. These events usually consist of a photo-op with a celebrity or keynote speaker followed by the banquet and or presentation. I must admit, it can be monotonous work but it has allowed me to the honor of meeting and photographing Presidents, 4 star generals, best-selling authors and top athletes. I digress.
One thing all of these have in common is that there is some sort of multi-media display at these events– A projection, screen, a TV, monitor or something similar and without fail, they all ask me to get image of these displays. I always laugh inside, because they already have the images and presentation, why do they want a still image of the display? Regardless, I comply. That brings us to today’s quick tip.
When photographing these displays it is important that we understand a few technical things. One, the display is typically backlit so our in camera meter will fool us every time. If using an in-camera meter, you will typically need to over expose the image because your camera will see the backlight and compensate with an under exposed result. Second, we need to understand that these images on screens cycle. While our eye perceives it as a single frame, it it anywhere from 60-90Hz, meaning the image cycles the screen 60-90 times a second. Just like our camera, these displays work with an additive light technique of Red, green and blue. When each color of light is combined we see a complete image. So, technically speaking the red, green and blue image is cycling at 60-90 times a second.
What does that mean for you? Your shutter speed must be priority when photographing a digital display. It is safe to use a shutter speed of 1/60 or less to capture the full image, meaning all there channels together. Below are two images of the same screen. One was captured at 1/60 sec and the other at 1/250th of a sec. The difference is noticeable. In the bottom images you can actually see each channel of color as it makes its way through the Hz cycle.
I hope this helps next time you need to photograph a screen. Whether for a corporate event, a commercial job or on a vacation at the museum, you can successfully get an image that works. Happy creating. Cris