LESSON 2
OPTICS
Lesson Objective:
When you have completed this lesson you will be able to:
1.
Identify
basic characteristic of lenses.
2.
Describe
focal plane and focal length.
3.
Identify
performance features of lenses.
4.
Describe
ratio and scale.
These objectives support the following tasks:
113-578-1006
Compute Electronic Flash Exposure and Ratio
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Photograph Subjects Using Various Focal Length Lenses
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Employ Photographic Composition
2-1. INTRODUCTION: In order to produce clear usable images, you must have a
special flat field lens.
In this lesson you will be taught basic optics and
how the different lenses work.
2-2. The purpose of a camera lens is to refract light rays in such a manner
that a sharp, clear image is formed.
Camera lenses are designed to function
with the least amount of error and to reproduce objects in a practical object-
image size relationship.
2-3. THE PINHOLE LENS. The simplest type of lens is a pinhole in a piece of
thin metal or black paper, (fig 2-1).
Only an extremely small part of the
light reflected by a subject passes through the pinhole to form an image in the
camera.
Figure 2-1.
Image produced by small pinhole.
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