Mercury Vapor Lights and Color Shifting
One of my oldest friends Matt has been playing softball for a season or two and this year I have finally had the time to come out and shoot his games. I really didn’t know what to expect with adult softball at first (I have to admit it seemed a little strange), but as I started to know the guys and see how hard they play I have built a strong base of respect for the sport.
After my first night of shooting a game I noticed that my white balance was shifting nearly every frame, making editing a huge pain. It was incredibly difficult to figure out why this was going on until I found a really delightful post by Guy Rhodes over at SportsShooter.com.
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One of the most difficult aspects of shooting softball is the stadium lights at night. The majority of small sporting arenas (think highschool gym’s, baseballs fields, and the like) use mercury vapor lights, which represent a huge problem when trying to get accurate color at high shutter speeds. These lights put out their light at 60Hz, or 60 pulses of light per second.
The human eye can’t detect these pulses, nor can we really get a hang of the color balance difference between them (I am assuming this is because the color shifts so fast our brain averages them out). The only way to get consistent color with each image is to shoot at a shutter speed of 1/60th or below, which is going to make for some pretty blurry photos! In my efforts to find a happy medium I ended up shooting at 1/120th, which gave me decent color but really unacceptable image quality (that was the first and last time I shoot below 1/500th for sports).
Guy illustrates this point effectively in this comparison image. The color shifting pattern that Guy experienced in his tests mimic almost precisely what I was seeing in Lightroom. It was so bad I was almost too embarrassed to send the team the images from that first game.
While I have not been able to overcome the color shift from the mercury vapor lights, I have a had a few realizations (and developed a couple tips) that have helped me:
- Set the white balance to Tungsten. While you still won’t get consistent color when you set the white balance, you will at least get consistently variable color. I don’t trust my camera to correctly figure out what should be white automatically, so when it’s set to Tungsten you will at least be getting color that most closely reflects what it should be.
- Shoot what is important. This is kind of anathema to the whole point of this post, but when you’re shooting sports you need to keep in mind what your clients are going to be looking for. If they have hired you to do accurate color work in a sports environment you will absolutely need to bring your own lights. In every other case they want to see facial expressions, dirt flying up from a slide, a great catch, etc. When they have found the image they connect with then go ahead and color correct it.
- (Wacky idea) Shoot at multiples of 1/60th. I have not tested this, but so far it’s been a good rule of thumb. The theory here is that if you keep with the pulse of the light you will tend to make an image in the middle of one of the pulses and therefore get uniform color across the frame. This particular tip seems so shady that I hesitate to post it, but take it for whats its worth.
As an side note: daylight savings time has come, which gives us photographers a extra hour of daylight (I see it as proof that God probably is a photographer). The direct effect? One less hour that I have to rely on mercury vapor lights and get to shoot in the gorgeous setting sun, like in The Closer’s most recent game!
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