What is the difference between 55mm, 85mm, 105mm and 135mm lenses for SLR cameras? How big is it for ordinary household use and travel?

55mm, 105mm, 135mm, etc. refer to the focal length of the lens. The smaller the number, the closer it is to wide angle. The higher the number, the closer the focal length is. Generally speaking, when taking photos, it mainly depends on what we take. If the lens does not change, it is fixed focus. If the lens is variable, it is a zoom lens. If we just want to take pictures of scenery when traveling, it is best to choose a zoom lens with a range of 28 to 280. If you want to be professional, prepare a few more lenses. The 55--280 telephoto lens can capture people or objects a hundred meters away, and the 55mm medium focal length lens is designed to capture people and objects in front of you, as well as landscapes. The 18-55 wide-angle lens or macro lens is specially designed to take panoramic shots of tall buildings in front of you or close-ups of flowers.