How to learn to use SLR photography? Where should beginners start?

The connection between the lens and the fuselage of a SLR camera is realized by something called a bayonet, which is usually three knives inside or three knives outside. In order to prevent the lens from falling off the fuselage, there is a locking tenon. Different cameras produced by different manufacturers have slightly different positions and operation methods of locking devices, which leads to different lens loading and unloading. For example, Nikon's F bayonet is equipped with three internal knives rotating counterclockwise, while Canon's EF bayonet is equipped with three internal knives rotating clockwise, and the initial position of the positioning point is different when the lens is inserted.

Why use a rotating bayonet? At first, the camera lens with interchangeable lens was connected to the fuselage with screws, just like screwing screws into nuts (such as M42 screws, which had a great influence). With the passage of time, screws can no longer meet the needs of new users. For example, screws can no longer basically meet the needs of full aperture metering and reduced aperture shooting, which is the most basic function of bayonet SLR cameras, so bayonet came into being.

Be careful when installing the lens, and be more careful when removing the lens. The lens must be vertical when it is pulled out, otherwise it will not only be difficult to pull out, but also damage the lens barrel or the bayonet of the fuselage. When rotating the lens, your hand should hold the lens barrel, not the aperture ring, focus ring or zoom ring. When installing the lens, the red dot on the lens should aim at the red dot on the fuselage and then insert it, and rotate it to the end in the required direction until you hear the locking "click" sound.

In a windy and dusty environment, try not to replace the lens, so as to avoid dust entering the mirror box, which may not only touch the CCD, but also enter the moving parts, leading to increased wear and even failure. If you need to change the lens in harsh environment, then turn the fuselage upside down and load and unload it with the bayonet facing down to avoid dust entering to the maximum extent. The replaced lens should be covered with front and back covers as soon as possible and put into a bag or lens barrel.