In Light Refraction and Lenses, you will learn about the lens, the lens material, the refractive index of glass, and how this can affect the light that enters a lens. Also, you will learn about the spherical aberration of a lens and how it can help in the science of photography. This article explains these concepts in more detail.
In terms of mathematics, the term spherical aberration is defined as a distortion in an image. The best way to think of it is to imagine a blurry or overexposed photo, then looking at the same photo with your naked eye and seeing it as clear as day. Now imagine that you are looking at the photo with the unaided eye, but it is just slightly blurred by the spherical aberration. This is the way in which this term is used in the context of optics and photography.
Image quality can be degraded by this aberration because it does not allow a properly exposed photo to be seen clearly when taken at a different distance. But, the aperture on the camera can also cause blurriness when it opens too wide or closes too tightly. As a result, there are several ways to correct for this aberration, and they all have different effects on how photos appear at different distances.
In Light Refraction and Lenses, you will study light refraction to determine the three different aberrations that affect the way images are exposed. There are three different forms of spherical aberration, the first being spherical aberration caused by imperfections in the optical design of the lens and how it distorts light rays entering the lens. The second form of spherical aberration is the spherical aberration of the image sensor and is what causes the blurred background in many photos taken using the digital camera. Finally, the third form of spherical aberration is caused by imperfections in the surfaces of the lenses that bend the light rays when they enter the lens.
In Light Refraction and Lenses, you will also learn about how the spherical aberration changes the optical properties of the lens. For example, lenses with very small spherical aberrations are better than lenses with larger ones, because the smaller ones do not distort light near the center of the lens, but instead cause light to deviate to the sides. Similarly, lenses with larger spherical aberrations cause light to deviate to the sides in the center of the lens, which makes the outside portion of the lens appear more blurred.
When you study optics in school, you learned that the optical properties of glass and lens materials change depending on the aberrations in their design. You also learned that the natural refractive index of glass (which is what determines the physical appearance of the glass) changes depending on how the refractive index of light changes, so that if the light is all the same, then you should be able to see a uniform look across the surface of the lens. In Light Refraction and Lenses, you will learn that this is only true if the lens is perfectly flat, which is a rare and difficult to achieve optical condition.
Because the refractive index of light changes with the number of other points of light that are entering the lens at one time, the characteristics of the lens change accordingly. For example, a spherical aberration that have just one point of light entering it and an equivalent point of light exiting will make the lens appear much bluer than a lens with two points of light and one point of light exiting, and the amount of light that make the lens appear less reddish depends on the spherical aberration that is present.
In Light Refraction and Lenses, you will learn about how spherical aberration causes a lens to appear redder, or bluer, as well as how you can use this knowledge to improve your pictures. In a similar fashion to determining the number of light rays that are passing through a lens, the location of light rays inside a lens determines its appearance in your final photo. By learning about spherical aberration, you can make great improvements to your photographs with a very simple solution.