Assignment 3 One Light

Using the 250 watt halogen bulb in the equipment closet, make a portrait by selecting a quality and direction of light to communicate an emotion that you feel about a person. Make an additional portrait that reflects the opposite feeling you have about the person. Explain in writing the laws of light that were at work in each portrait.

Lesson 3 Direction of Light, Diffusion, Diffraction and Using One Light

Examples of diffusion

What happens when a point source (like the sun or our Halogen Bulb) falls on a solid white sphere:
1. A highlight is created
2. A cast shadow is created
3. A core is created in the transition of the highlight and the shadow
4. A cast shadow is created
5. A specular or incident highlight is created with the highlight (it is the direct reflection of the light source)



The cube is tilted to reveal 3 sides equally. When a point source (our Halogen bulb) is placed over and as close to the camera lens as possible, all three sides reflect equally. When the light is moved to the left and up, the 3 sides reflect light in unequal ways and appear as 3 differentvalues

Assignment 2 Demonstrate the 3 Laws of Light in One Photograph

In one photograph using one light source clearly demonstrate the 3 laws of light at work. Include the light source in the photograph. The subject is the light. Think of it as more of a physics project than a photograph. Use a dodging tool  to prevent the light from flaring the lens.  Try to crop out any rigging you might use and make the image about the light.

Lesson 2 Light Travels in a Straight Line

Abelardo Merrell Photograph








The camera obscura is an example of light traveling in a straight line

Lesson 2 Angle of Incidence Equal Angle of Reflection

Light reflected from a metal surface with angle of incidence equal to the angle of reflection. The dashed line is perpendicular to the surface.

Light reflection from a) smooth surface (specular reflection) and b) rough surface (diffuse reflection). In both cases the angle of incidence equals the angle of reflection at the point that the light ray strikes the surface.

Diagram of a Parabolic Reflector

World War II Search Light

Assignment 1 Inverse Square Law

1. Using 3 identical 4x5 grey cards set 1 foot apart, overlapping slightly and placed at a 45 degree angle from the camera angle. Make 4 photographs of the cards with the light 2 feet, 4 feet, 8 feet, 16 feet and 32 feet from the middle card. Use an incident meter on the middle card to give the correct exposure. The middle card should have the same value on each photograph.  Use Lightroom to weak the middle card until they all read the same value.

2. Use 3 4x5 cards a black card in front, a grey card in the middle and a white card in the back. Using the same single point source make all 3 cards appear to be the same value. You can move the cards and the light source until it works.

3.  Create a blog on blogger using your google account and use the simple template.

4.  Send the url for your blog to ccs@nyc.rr.com by next Monday.

Lesson 1 Inverse Square Law

The inverse square law states that the intensity of the light from a point source diminishes inversely to the square of the distance.  I=1/d²  Here is a better illustration that what I drew on the white board.

I got this next chart from Lee Varis's website.  He illustrates here the relationship of 18% grey to a modified 10 step zone system, 50% that you would see in Lightroom's histogram and the number 118 you see in Photoshop's histogram using RGB color space.  



Here is the results of our test in class with the middle grey card adjusted in Lightroom and tweaked in photoshop to look the same.  You can see the Front card gets darker in relation to the Middle card as the light is moved further away and the Back card gets lighter as the light is moved further away.

Ben Kong's Version

Our Class Demonstation Results

Production Stills