The lens is the camera's eyes, so once it is dirty, marked or scratched, the image quality will be reduced. The dust and dirt attached to the front lens of the lens always bother the photographer. Although it is said that the lens should not be cleaned when it is unnecessary, it is necessary to keep the lens clean, otherwise it will affect the image quality, and the lens will cause glare. Will increase.

　　1) Use a blower or soft brush to clean the floating dust

　　 Use a blower or soft brush to remove the floating dust on the surface Or small particles, if wiped with a cleaning cloth, they may inadvertently drive dust or particles to rub against the lens and cause scratches. When using a thin fiber soft cloth or a special lens cloth or lens paper to wipe off the fingerprints on the lens, the action must be gentle.

　　2) Use a special lens cleaning fluid

　　 For those stubborn marks that should not be wiped off, you need to use a cleaning fluid . Be sure to use a special lens cleaning solution. Never try to wipe the lens with ammonia or other household detergents, which may cause irreparable damage to the lens. The special lens cleaning liquid should be poured on a clean soft cloth, not directly on the lens. When cleaning the lens, don't forget the rear lens of the lens. The dust attached to the upper lens design surface may enter the camera and stick to the image sensor, causing marks on the final image.

　　3) Use lens pen

　　 You can use special accessories such as hama lens pen to protect you Of the lens. It has a retractable brush to clean dust and dirt, and the other end is a round handle that can bend with the curvature of the lens surface. Gently press it on the dirt on the lens, and then slowly rotate it a few times. Disappeared.

　　4) Use a soft cloth to clean dirt

　　 The lens and body mount will inevitably appear dusty with use And dirt. If the connected contacts are dirty, electronic components such as the autofocus system will be affected. You can use a soft and dry cloth to gently clean the dirt.

　　5) Install the filter and front and rear covers to prevent dust

　　 Installing a filter in front of the lens is the best way to protect the lens One of the good methods. Like a UV lens or a skylight lens, it can always be installed on the front lens of the lens to protect the lens. After all, scratches or damage to the lens are irreversible, and the filter is relatively cheaper. Finally, when you are not using the lens, remember to cover both the front and rear caps of the lens. The lens cap can prevent dust and dirt from invading the optical lens.

　　Lens focal length

　　The focal length is a measure of the concentration or divergence of light in an optical system. The distance from the optical center of the lens to the focal point of the light. It is also the distance from the center of the lens to the imaging plane such as the film or CCD in the camera. An optical system with a short focal length has a better ability to gather light than an optical system with a long focal length. Simply put, the focal length is the distance between the focal point and the vertex of the mirror.

　　lens specifications

　　 The common lens focal length classifications are: 8mm, 15mm, 24mm, 28mm, 35mm, 50mm, 85mm, 105mm, 135mm, 200mm, 400mm, 600mm, 1200mm, etc., as well as an ultra-telephoto telephoto lens up to 2500mm.

　　 SLR refers to single-lens reflex viewfinder, namely SLR (SingleLensReflex), which is the most popular viewfinder system today, and most 35mm cameras use this viewfinder. In this system, the unique design of the mirror and prism allows the photographer to directly observe the image through the lens from the viewfinder. Therefore, it is possible to accurately see the same image that the film is about to 'see'.