With the official debut of Sony A7RII, I believe many friends will compare it with Canon 5DS and Nikon D810. An old question is raised again: Which is better, a DSLR or a Sony mirrorless camera? Can a Sony full-frame mirrorless camera replace a DSLR? Sony's interchangeable lens camera e-mount (ILCE) is structurally a mirrorless camera. Domestically, Sony has registered the Chinese trademark "Micro-Single", which means "small size, SLR image quality". So, Sony's tiny camera is a mirrorless camera.

A few days ago, Sony produced a concept promotional video with a simple and crude content: In a desert, a huge piece of glass fell apart and was shattered, with the lyrics "Release me." As a result, an A7II revealed its true content - if it were described in Chinese, it should be "break and then stand". SLR, not reflex - what is "reverse"

The full name of SLR camera is "single lens reflex camera", and the full name of mirrorless camera is "mirrorless interchangeable lens camera". Whether it's a DSLR or mirrorless, "reflective" refers to the "mirror" structure - just find a DSLR camera, take off the lens, and see the glass inside? That's a mirror.

The original purpose of the mirror was to facilitate viewing. As early as the mid-18th century, the camera obscura with built-in reflectors had become the main tool for painters to sketch from life. From the birth of the SLR camera in 1884 to 1948, the waist-level viewfinder with a reflector and frosted glass was the main viewfinder method of the SLR camera. In 1949, the Contax S SLR camera launched by Zeiss had a reflector-pentaprism structure, and for the first time achieved eye-level front viewfinding - which is also the main viewfinder method for today's SLR cameras.

As camera operation changes from fully manual to fully automatic, reflectors also play a new role. First, the early TTL metering element behind the lens was placed on the lens (later moved to the viewfinder). Then, it is important to realize the important foundation of TTL autofocus function. The mirrors we see today are actually half-reflecting mirrors. The light that passes through the lens falls on the reflector, and part of it is reflected upward 90 degrees into the viewfinder, and finally reaches our eyes; the other part passes through the reflector and is reflected by the sub-reflector before reaching the autofocus module, allowing the camera to achieve rapid autofocus.