Light and the Photographer

Light is the primary working tool of the photographer. Light is the visible portion of the electro-magnetic spectrum. The spectrum starts from red, the weakest of rays, all the way to violet which is the strongest of rays.

Light rays from the sun are considered white and they contain all the colors of the spectrum. Black is the absence of any color.

When we place a prism in front of a white ray, the prism will diffract (separate) that light into
all the colors of the spectrum.

When we place a LENS in front of any ray, that lens will simply refract (bend) that ray.

In the illustration below, you will see a point where the rays meet.  That point is also called the film plane.   At that point, all light rays of the subject must meet to accomplish sharp, focused pictures.

So, being in focus simply means moving the lens elements forward and backward until all the rays coming toward the camera from the subject meet at one point; the focal point on the film.

The human eye

The human eye looks basically like the crude drawing below. The lens at the left side of the eye focuses light rays onto the retina at the right. The retina converts light rays into electrical impulses that are sent to the brain.  Our brain then tells us we are seeing a bit of light.

Both digital and film cameras have a lens in front to capture light rays. Light rays enter through the lens to the film, or digital sensor; both of which are sensitive to light

More on Light Rays

We have different labels for describing the rays we see. Here are a few basic ones:

• Transmitted Rays

When you look at a stop light the top light is red, the middle is yellow, and the bottom light is green. That light is transmitted by putting a light source behind a colored filter.

• Direct Rays

When you look directly into the sun, a camera’s flash unit, or a flashlight you are looking at direct light. The light you see is coming directly from the source.

• Reflected Rays

When you look at anything, you can see that object because direct light is shining on it and being reflected back into your eyes.

• Ambient Light:

Think of ambient light as stray light – light rays that are being bounced around from all sorts of sources. If direct or reflected light on the subject is stronger your subject will appear clearer and less hazy.

• Available Light

Available light simply means whatever light is present when not using flash or other sources of light.

Understanding Color

The COLOR of the subject is determined by the color of the light source and the color of the subject.

Photographic film records light as it actually is. Your eye/brain, however, will always correct light back to “normal”. Your brain is constantly compensating.

That is … if you are inside a place that is lit with light bulbs, those light bulbs actually transmit a reddish-brown light and white objects will be recorded on film as reddish-brown. However your brain will correct that light and a white object will appear white.

Same thing happens inside a place illuminated with fluorescent bulbs. Fluorescent bulbs actually transmit an ugly greenish-yellow light, but your brain corrects that light and it appears white to your eye. Film records that light as greenish-yellow.

  

Fluorescent light contains only enough green and yellow light to photos turn out a bit “off” in color.  However, by using a magenta filter in front of the lens, the overall lighting is more natural and “warm”.

We will discuss this at length later on. Right now just understand that it happens.

RED GREEN and BLUE are Primary Colors

Some people (see some of the comments below) just refuse to believe that green could be a primary color! Well if you’re still not a believer check out how red and green make yellow.

RED light rays only contain red because it is a primary color. 
So GREEN light rays only contain green,  
and BLUE rays only contain blue.  
Again, that is because these are the PRIMARY colors.

Secondary colors - 
magenta, 
cyan, and 
yellow (yellow)
are considered SECONDARY colors because each one is a mix of two PRIMARY colors. Mixing PRIMARY & SECONDARY colors will give you TERTIARY (third tier) colors …. making up all the visible colors in the spectrum.

You can see how PRIMARY colors and SECONDARY colors mix from the chart below:

 

Here’s another image to show you how using the primary colors, red, green and blue, you can produce the secondary colors.

Do Not Worry; there will be no test on this. Just read it and think about it for a while. This concept can be a little confusing as in school we learned that the primary colors are different. We must remember that color in the printing world is what we learned in school, but color combinations are different for light. For photography, we must learn the colors of light, not the colors for printing. In photography we are talking about RGB or colors of light that join together to make white, whereas in print all primary colors joined together would create a neutral color, or gray.
 

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