Lens aperture is divided into three main categories: fixed aperture, cat’s eye aperture and iris diaphragm. Fixed aperture lenses cannot adjust the size of the aperture and are usually used in low-end devices such as mobile phone cameras. The cat’s eye aperture consists of two thin metal sheets with semi-elliptical or semi-diamond shaped holes that can be adjusted in size and is widely used in entry-level cameras. Iris-type aperture consists of multiple curved aperture blades, the number of blades can be up to eighteen, the aperture can be adjusted in a wider range, the light transmission holes are close to round, so it is widely used in consumer cameras and DSLR cameras.

The iris diaphragm changes the size of the aperture through the clutching of the blades, and the multi-blade design makes the light transmission aperture closer to a circle. In order to demonstrate the effect of iris aperture, I chose a Nikkor AF 50/F1.8D lens for demonstration. The lens’ aperture ring offers a full aperture range from F1.8 to F22 and consists of seven aperture blades. When the aperture ring is fully open, the light-through hole is bright and wide, and more light is passed through.

In summary, different types of lens aperture has its own characteristics, fixed aperture structure is simple, cat’s eye aperture is inexpensive, while the iris aperture provides a larger aperture adjustment range and better image quality, so it is widely used in modern photography.

The multi-blade design of the iris aperture not only increases the flexibility of aperture adjustment, but also reduces halation at the edge of the aperture and improves image quality. In addition, the iris aperture can also achieve different depth of field effects at different aperture values, providing more creative space for photographers. When using the iris aperture lens, the photographer can choose the appropriate aperture value according to the shooting needs, in order to obtain the best imaging effect.

In short, the classification and selection of lens aperture is crucial to photographic creation. Fixed aperture is suitable for low-end equipment, cat-eye aperture is suitable for entry-level cameras, while iris diaphragm is suitable for high-end photographic equipment, which provides photographers with more room for creativity. Understanding the different types of lens apertures helps photographers to better master their photography skills and improve the quality of their shots.