Formulas and reasoning behind finding focal length

In summary, focal length is a measurement of the distance between a lens and its focal point, where light rays converge to form a clear image. It is calculated using the formula f = (d x D) / (d + D), where f is the focal length, d is the distance between the lens and the object, and D is the distance between the lens and the image. The longer the focal length, the narrower the angle of view and the higher the magnification of the image. Understanding the formulas and reasoning behind focal length is important in photography and optics.
  • #1
Apoxyus
hey can someone give me the formulas and resoning behind finding focal length, magnitude of radius curvature, and other optic stuff. Thank you.
 
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  • #3
Thanks
 

1. What is the formula for finding focal length?

The formula for finding focal length is f = (R1 * R2) / (R1 + R2), where R1 and R2 are the radii of curvature of the two surfaces of the lens.

2. How does the focal length affect the image produced by a lens?

The focal length of a lens determines the magnification and field of view of the image. A shorter focal length results in a wider field of view and a smaller image, while a longer focal length produces a narrower field of view and a larger image.

3. What is the relationship between focal length and lens power?

The lens power is inversely proportional to the focal length. This means that as the focal length increases, the lens power decreases, and vice versa.

4. How do you measure the focal length of a lens?

The focal length of a lens can be measured by placing the lens in front of a light source and measuring the distance between the lens and the point where the light is focused to a sharp point. This is known as the focal length method.

5. Can the focal length of a lens be changed?

Yes, the focal length of a lens can be changed by adjusting the distance between the two surfaces of the lens or by using additional lenses to alter the path of light. This is how zoom lenses are able to change their focal length and produce different magnifications.

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