The main working principle of a DSLR digital camera

In the working system of a DSLR digital camera, the light passes through the lens to the mirror, is refracted to the upper focusing screen and forms an image, through the eyepiece and the pentaprism, we can see the outside scene in the viewing window. In contrast, a digital camera can only see the image through an LCD screen or an electronic viewfinder (EVF). Obviously, images that are seen directly are easier to shoot than images that are seen through processing.

When shooting in DSLR, when the shutter button is pressed, the mirror pops up, and the shutter curtain in front of the sensor (CCD or CMOS) opens at the same time, and the light through the lens is projected onto the original sensor, and then the rear mirror immediately returns to its original shape, and the image can be seen again in the viewing window. This structure of the single-lens reflex camera determines that it is shot completely through the lens focus, it can make the image seen in the viewing window and the film forever the same, and its framing range is basically the same as the actual shooting range, which is very conducive to intuitive framing and composition.

The biggest difference.

The SLR can change the lens.

Consumer digital cannot.

The SLR is framed through a reflector and a pentahed-sided (prism) mirror.

The consumer machine is framed by LCD.

Single-lens reflex is relative to double-lens reflex cameras.

There are two lenses for double reflex.

One is used for shooting as usual**.

There is also a lens that is dedicated to framing and cannot be photographed.

The consumer machine is one lens, not a dual lens or a multi-lens.

Hope it can help you a little bit.

Imaging principles

In this system, the unique design of the mirrors and prisms allows the photographer to observe the image passing through the lens directly from the viewfinder.

As can be seen in the construction diagram of a single-lens reflex camera, the light passing through the lens reaches the mirror, reflects to the upper focusing screen and forms an image, and through the eyepiece and the pentaprism, we can see the outside scene in the viewing window.

The light passes through the lens and is reflected by the reflector into the frosted viewfinder screen. Through a convex lens and reflected in a pentaprism, the final image appears in the frame.

When the shutter is pressed, the mirror moves in the direction indicated by the arrow, the mirror is lifted, and the image is captured on the CCD or CMOS, as seen on the viewfinder.

The advantage of DSLRs over rangefinders is that what you see is what you get, and the angle of the image in the viewfinder is the same as the angle at which the final film is produced.

However, compared with the rangefinder camera, the posterior focus of the SLR camera lens should be able to image at the position of the reflector and the focal plane position of the image sensor at the same time, and a false focus must be generated before the imaging focal plane, which causes the structure of the optical lens of the SLR camera to be more complex and larger, and the imaging effect is not as direct and transparent as the rangefinder camera. At the same time, the volume of the "reflector" should be thick and bulky.

SLR is a single-lens reflex viewfinder camera throughout the whole process, and a single lens refers to the photographic ** light path and the framing light path share a lens, unlike the rangefinder camera or double reflex camera with independent lens for the framing light path.

Reflection refers to a flat mirror in the camera that separates the two light paths: the mirror falls down during framing, reflecting the light of the lens to the pentaprism and then to the viewfinder window; When shooting, the mirror is quickly raised, and the light can hit the film or the image sensor CMOS or CCD.

The SLR has only one lens, and it is used for both photography and framing, so the parallax problem is basically solved.

When framing, the light from the subject is focused by the lens, reflected by the oblique mirror to the focus, and then through the top ridge"Roof prism"Reflection, the person who captures the beam can observe the scene through the viewfinder eyepiece, and the image is the same as the scene from the top, bottom, left and right, so it is very convenient to frame and focus.

When shooting, the mirror will immediately pop up, the lens aperture will automatically shrink to a predetermined value, and the shutter will open to make the film light-sensitive; **When the shutter closes at the end, the mirror and lens aperture reset at the same time.