When shooting portraits, we often want to separate the portrait fr•om the background. A shallow depth of field can achieve this goal, ←so we need to shoot with a large aperture.

When shooting scenery, we want to get clear photos both far and near, so πwe need a deep depth of field, and we need to☆ shoot with a small ap•erture.

Types of visor

Fixed visor

The simplest camera has only a fixed aperture wΩith a round hole-the Waterhau ser aperture. The original variable aperture was just a series of circular ♠holes of different sizes arranged around a disk with a central axis; rotati∑ng the disk can move the ÷appropriate size of the circular hole to t×he optical axis to achieve the effect of controlling the aperture. In thφe middle of the nineteenth century, John Waterh←ouser invented this kind of aperture.

Mobile phones often use fixed shad∞ing rings

cat's eye aperture

The 　　 cat-eye diaphragm is composed of a sheet of me©tal with an oval or diamond-shaped hole in th♠e center, and two sheets of metal with a semi-elliptical or semi​-diamond-shaped hole are aligned and moved relative to each oth•er to form a cat-eyeλ diaphragm.

cat-eye hood is mostly used for sim<ple cameras.

The 　　"iris" type aperture is composed of a↑ plurality of overlapping arc-shaped thin metal blades. The clutαch of the blades can change the size of the central circular βaperture. Some cameras can change' the size of the aperture by turning the  ring on the lens barrel, while some ca>meras use a microprocessor chip to control a micro-motor to automatically chan♥ge the aperture of the aperture. There ↔can be as many as 18 curved thin metal blades. The more arc-shaped thin met¶al blades, the closer the aperturΩe is to circular. By designing the shape of the thin metal blades by the εcomputer, only 6 thin metal blades can be used to obtain a near‍ly circular aperture.

instantaneous aperture

The aperture of a SLR camera i₹s an instantaneous apertu↔re, and only when the shutter is opened, the aperture is reduced to¶ a predetermined size. Usually the time circle is in the largest posit≈ion.

SLR lens uses this kind of

and shutter aperture

Some simple cameras have an aperture that also functΩions as a shutter. Most of these dual-blade cat-eye apertur"es are different from simple cat-eye apertures: thδe shutter aperture is usually c→ompletely closed.

Large and medium format cameras areδ mostly inter-lens shutter

At the moment when the shutter is press✔ed, the double-blade aperture opens to a pred"etermined aperture, and after ×maintaining this aperture for a predetermined shutter ope★ning time, it closes immediately: in this way, ≤the aperture doubles ≥as a shutter.