How do optical spherical lenses achieve focusing and imaging in photography applications?
Publish Time: 2024-12-31
The application of optical spherical lenses in photography mainly involves the process of focusing and imaging.1. Refraction principleThe basic principle of spherical lenses is to use the refraction property of light. When light passes from one medium (such as air) to another medium (such as glass), the propagation speed of the light changes, resulting in the deflection of the light. This deflection phenomenon is called refraction. Spherical lenses are usually composed of two spherical surfaces, and light will be refracted twice when passing through these two spherical surfaces.2. Types of lensesThere are two main types of spherical lenses: convex lenses and concave lenses.Convex lens (converging lens): After passing through a convex lens, light will converge to the focus of the lens. A convex lens can converge parallel light from a distant object to a point, which is called a focus.Concave lens (diverging lens): After passing through a concave lens, light will be dispersed. A concave lens disperses parallel light into a virtual focus.3. Focusing processIn photography, focusing refers to adjusting the position of the lens so that the light emitted from the object forms a clear image on the photosensitive element. The focusing process can be achieved through the following steps:Object distance determination: Determine the distance from the object to the lens.Adjust the image distance: Move the lens or change the position of the lens group so that the image distance satisfies the lens imaging formula. This is usually achieved through the camera's focus ring or autofocus system.Clear imaging: When the image distance is adjusted correctly, a clear image will be formed on the photosensitive element.4. Image quality of spherical lensesSpherical lenses may produce some aberrations during the imaging process, which will affect the image quality. Common aberrations include:Spherical aberration: Due to the uneven curvature of the lens surface, the refraction angle of light at different positions is different, resulting in blur at the focus.Chromatic aberration: Different colors of light have different refraction angles when passing through the lens, resulting in different focal positions of different colors of light, resulting in dispersion.Coma: When light is incident from the edge of an object, the image will appear blurry similar to the tail of a comet.Field curvature: The lens may bend the imaging plane, causing the image to be unclear at the edge.To reduce these aberrations, modern camera lenses are usually composed of multiple lenses, which can correct various aberrations and improve the image quality.5. Practical applicationIn photography, spherical lenses are widely used, from simple SLR camera lenses to complex zoom lenses. By adjusting the focal length and focus of the lens, photographers can achieve different shooting effects, such as depth of field control, magnification adjustment, etc.Optical spherical lenses achieve focusing and imaging by refracting light, and their imaging effect is affected by the object distance, image distance and focal length. By adjusting the lens position, the light can form a clear image on the photosensitive element. In order to improve the image quality, modern camera lenses usually adopt a multi-lens combination design to reduce aberrations.
