camera gain

A mirrorless camera, sometimes referred to as a mirrorless interchangeable-lens camera (MILC), is a digital system camera which does not use a reflex mirror to present an image through a viewfinder. They have come to replace DSLRs, which have historically dominated interchangeable lens cameras. Other terms include electronic viewfinder interchangeable lens (EVIL), compact system camera (CSC), and digital single-lens mirrorless (DSLM).
When compared to similar DSLRs, these cameras can be smaller, lighter, and quieter.
In cameras with mirrors, light from the lens is directed to either the image sensor or the viewfinder. This is done using a mechanical movable mirror which sits behind the lens. By contrast, in a mirrorless camera, the lens always shines light onto the image sensor, and what the camera sees is displayed on a screen for the photographer. Most mirrorless cameras also simulate a traditional viewfinder using a small screen, known as an electronic viewfinder (EVF).
DSLRs can act like mirrorless cameras if they have a "live view" mode, in which the mirror moves out of the way so the lens can always shine onto the image sensor.
Many mirrorless cameras retain a mechanical shutter. Like a DSLR, a mirrorless camera accepts interchangeable lenses. Mirrorless cameras necessarily have shorter battery life because they need to power the screen and sensor at all times.

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