Posts Tagged ‘color temperature’

Video Production 101 – White Balance

Friday, February 5th, 2010

This question came to me recently:

My videos have been oddly yellowish. I read somewhere about ‘white balancing.’ I have a Sony Cybershot. Do I white balance on the camera during filming, do I do it during editing, if so where? Thank You so much for your help!

Although our eyes can’t perceive it, certain light sources give off a particular color temperature. These varying degrees of color are represented on the Kelvin scale. Tungsten bulbs burn at about 3200 degrees Kelvin, while sunlight burns at about 5600 degrees Kelvin. However, the color temperature of the sun doesn’t stay constant. It’s constantly changing as morning turns to afternoon and as afternoon turns to dusk. Our eyes can automatically compensate for this change in color temperature, but video cameras cannot. So, they need to be calibrated every time the light source changes. Otherwise, the footage can come out with an orange tint, blue tint, or even a green tint.

Calibrating a video camera to ensure correct color representation is called white balancing. Many cameras come with preset white balance settings for diffewhite-balancerent shooting situations – indoor, daylight, cloudy, etc. However, conducting a manual white balance on your camera is the best way to ensure that all colors within your scene are represented correctly. There’s a great tutorial on color temperature and white balancing here. You can also read my production tip for shooting under fluorescent lights, which pose a different set of challenges.

To white balance, turn your camera’s white balance setting to manual. Then, hold a plain, white sheet of paper in front of the camera and zoom in until the paper fills the screen (make sure you hold the paper under the light source under which you will be filming). Then (this is true of most cameras with manual white balance), press and hold your white balance button until your camera confirms that a proper white balance has been set. Then, you’re ready to shoot. Just remember to re-white balance every time you change locations and lighting setups. Read this post for tips on how to adjust your white balance to a warmer or cooler tone.

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Shooting the Grocery Store

Thursday, September 3rd, 2009

Twice this week I have been up all night working as the DP for Filament Artists’ latest short film, entitled “Love at the Grocery Store.” The screenplay was selected as the winner of the Production Prize at the 2008 Sidewalk Moving Picture Festival and will premiere at this year’s festival on September 26.

Shooting inside a grocery store has its particular set of challenges and so I wanted to pass along some things to remember if any of your projects take you inside the same environment.

LIGHTING & TONE

Most grocery stores are lit with fluorescents, meaning that everything will be washed with a flat, even, diffused light. If the tone of your piece calls for high-contrast lighting, you might want to see if the grocery store manager will allow you to turn off the overheads, giving you more freedom to light as you see fit. If this isn’t possible and you still want to create a surreal look with high-contrast, you can always light your subject with hard, direct light, that comes from the side, creating harsh shadows. The hard light will force you to stop down your f-stop. This should darken the background, while leaving your subject properly exposed.

Since fluorescent bulbs cast an even, diffused light, your subjects can come out looking drab, flat, and uninteresting. You will need some additional light to help create more natural skin tones and make colors that pop just a little more. However, reflectors alone won’t get the job done. They just won’t provide enough reflected light underneath fluorescent bulbs. And aiming a 1Kw or 650w tungsten at your actors will create an obvious difference in color and tone.

To give your shots a warmer look under fluorescent lighting, start by using your tungsten lamps and reflectors together. Mount a large piece of white foam core onto a c-stand and then bounce light from a 1Kw lamp onto your subject. The result is a soft, diffused light that isn’t overbearing, and yet one that warms up the scene a bit more. And I always recommend a little rim lighting to help your subjects stand out more from the background.

Bear in mind that the above solution assumes that you want a natural, warm tone for your project. If the mood of your film is a bit darker and somber, then you might like the sterile, flat, “blue” tone that the existing lights create.

LIGHTING & COLOR

Shooting under fluorescent lights can affect the white balance of your shot. If not properly monitored, the lights may cause the color of your shot to drift slowly from a cool tone to a warm tone, then back again.

However, I’d advise you to look back at our previous post for a more extensive look at shooting under fluorescents. To that article let me add that using a Kino light bank will be a big help. Kino’s do use fluorescent bulbs, but unlike the bulbs installed overhead in a grocery store, these bulbs burn at a constant color temperature. This will give your shots more accurate color representation while maintaining a consistent look with the rest of the lighting in the store.

Fluorescent lights might also appear green on camera. A green tone might work well for your project if the mood is more sinister and the location of your story more urban, decayed, or threatening.

Look for the comedy, “Love at a Grocery Store” at this year’s Sidewalk Moving Picture Festival. The screening is tentatively set for 9pm at the Alabama Power Building.

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Production Tip: Shooting Under Flourescents

Tuesday, March 31st, 2009

Shooting under flourescent lights while on location can be a nightmare. First, the light emitted by the bulbs creates a very flat, even, and uninteresting scene. Second, each flourescent bulb gives off light at a different frequency, which can play nasty tricks on your camera’s CCD. For those of you who have been forced to shoot under flourescents, you may have noticed that the color of your footage will gradually shift from a cooler tone to a warmer tone, then back again. Ideally, it would be best to turn off all flourescents while on location and set up your own lights to ensure maximum control over the lighting situation. However, this isn’t always an option – especially if your shoot is more run-and-gun. So, how can you best control the lighting when using your own light kit isn’t always an option?

  1. The very first thing you want to do is set a MANUAL white balance. Don’t leave control of the color in the hands of the camera’s auto white balance function. This could make things worse and the color shift could become even more noticeable.
  2. Try using a minus green card for your white balance. Flourescent lights will add a green tint to your scene. White balancing off of a minus green card will negate that tint and give your scene a more natural look. However, I’ve noticed that some green cards when used with certain cameras will make the scene look a little too rosy. you may have to experiment here.
  3. Adjust the camera’s shutter speed to 1/120. Usually, this will sync up the camera’s shutter with the rate at which the flourescent bulbs give off light, preventing the scene from color shifting. In my experiences, this has worked well with the Canon XL-1s, Canon XL2, Panasonic DVX-100, and Panasonic HVX-200.

Those are a few tips for correcting in-camera. If you ARE able to use your own lights, here are a coupe of additional suggestions:

  1. If you are able to use your own lights, but are unable to turn off the overhead flourescents, be sure to add green gel to your lights to compensate for the green tint emitted by the flourescent bulbs. Then, after adding the gel, get a manual white balance.
  2. Invest in a Kino-Flo light bank. the flourescent bulbs in a Kino kit emit light at a constant color temperature, so you don’t have to worry about fluctuations in the color of your scene.

Following these suggestions will certainly help compensate for an unpleasant lighting situation. I would also suggest that you visit the forums at Cinematography.com for tons of useful information on camera techniques.

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