Color temperature

In my last post I mention little bit about color temperature. Each light source has its own “temperature,” and thus they glow at different colors. Most appear to our eyes as normal white light because our brains compensate for the color shifts. A tungsten or incandescent light bulb will have a warm orange/yellow glow; Fluorescents will have a green tint, LEDs will appear bluish and cold. Today’s cameras, as sophisticated as they are, are just dumb machines and record the light as it really is. The cameras have what’s called “white balance” presets for the different light sources. Although most people (myself included) use the auto setting (which tends to be fine in most cases, you can switch between tungsten, fluorescent, flash, daylight, etc., if you wanted to).

In the old days, most film was balanced for daylight (though you could buy film that was made for, say, tungsten lighting). Shooting it under artificial light, the pictures would have a different color cast, depending on the light source. One could correct for it in the darkroom or put a filter that was the opposite color of the light source, thus canceling out the color shift.

With today’s digital cameras, one can correct the color change with a filter over the lens (as in the old film days) or fiddle with the camera’s white balance , but you have to know what the light source is. You can also correct for the color in the digital darkroom with a image editing program such as Photoshop or Lightroom.

Most people shoot their cameras in the JPEG, which is a compression format. When you take a picture as a JPEG, your camera compresses the photo by comparing pixels then throwing some out that it deems unnecessary. The trouble with that is some of the digital information that makes up an image is lost, and it becomes more difficult to do the photo corrections such as color shifts or fixing over/under exposures.

But with most DSLRs (and a few point-an-shoot digital cameras) you can set the camera to record images in what’s called the raw format. Raw is lossless and records all the pixels of an image. With all the information available, it makes it much easier to do any corrections a photo might need. The downside is that the images take up much more memory that those compressed in JPEG. Also, because raw photos are in an unprocessed format and are unable to be printed or even viewed, you need the tools usually found in the high end (re: expensive) software to access the raw files.
Here are 2 examples of color temperature.
The first photo is of the Record company car that I drove to an assignment at night at Franklin High School in Stockton. Although the overhead light in the parking lot was enclosed I guessed that it was what’s known as a sodium vapor light. Its signature color is a sickly orange cast given to everything it touches. It is so pronounced that even the mind can’t compensate for it. I have never been able to correct for it when shooting JPEGs no matter how much I fiddle with it in Photoshop. But shooting in raw I easily fixed the problem. The raw converter portion of the software has a feature where you can do what’s known as a white balance “click.” Just find a neutral color, a black, white or gray, in the photo and take the white balance tool and click on it. Instantly everything in the photo turns to its true color.
On another assignment to shoot a men’s basketball game at the University of the Pacific Spanos Center in Stockton, I saw a full moon rising over some leafless trees in the parking lot. A nearby light on a pole illuminated a tree as the moon peeked through some thick cloud cover. This time the light looked to my eyes to be white. But when I returned to the office and downloaded the photos, I realized that it must have been a fluorescent light, because the branches of the tree were an eerie green that made it look as if it were a scene from a Halloween horror movie. The moonlight, which essentially is the same as regular daylight, made the portion of the clouds that could be seen a neutral gr ay save for a reddish ring around the moon. I shot it in raw and by doing a white balance “click” on the branches of the tree, they turned their natural grayish color. However when dealing with more than one light type source in the same photo, if you correct for one, the other is likely to be thrown off. While the branches were right after the color change, the clouds turned a purplish color, and the ring around the moon became a bright magenta.

So when it comes to night photography and knowing about color temperature, it can affect how you take your pictures and can help you make your decisions on what steps to take on correcting the color shifts.


Here are the rules to the latest Readers Photo Challenge assignment: Night

1. Entries can be emailed to Type in “Night” in the subject line.

2. Photos have to be shot between Feb. 17 and Mar. 2.

3. Include your name (first and last), hometown, and the kind of camera/lens you used and where it was taken (ie: “Weber Avenue in downtown Stockton.”

4. If there is a recognizable person in the photo, please identify them (name, age, hometown).

5. The subject is up to you but it must be shot outdoors at night, any time after sunset to before sunrise. It can be a found situation or a created one.

6. Please feel free to include any interesting anecdotes or stories on how you took the picture.

7. The deadline for submission is Sunday, March 2. The top examples will be published on Monday, March 10 with an online gallery of all the photos on the same day.

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