What is an aperture wheel?

An aperture wheel is a device used in optical instruments, such as cameras and microscopes, to control the size of the aperture through which light passes. By adjusting the aperture size, users can regulate the amount of light that reaches the sensor or film, influencing exposure and depth of field. This feature allows for greater creative control over images, enabling adjustments for various lighting conditions and desired effects. The aperture wheel typically consists of multiple openings of different sizes that can be rotated into position.