How to evaluate the quality of lens?

Everything about lens-evaluate basic lens options and good image quality. These four lenses all include ultra-low dispersion lenses and aspherical elements, which are optical elements used to eliminate distortion and chromatic aberration (color "ghost") and can produce very clear images. Considering the low (or reasonable) price, their image quality is very suitable for all photographers who have high requirements for photos. Small size. From only about 204 grams (18-55mm lens) to about 535 grams (18-200mm VR lens), these four lenses are light in weight and small in size, so users can easily take one of them out of the camera bag and put it on the D40/D40X for shooting. Fast, close focus. These lenses focus quickly and quietly. Although they are not macro lenses, they all allow users to focus at a distance of 0.3m or 0.6m. They are AF-S lenses with built-in focus motors, and D40/D40X are necessary. When using a non-AF-S or AF-I lens, the user's camera cannot focus automatically (this will be explained in detail later in this chapter). Figure 1 and Figure 2 show how much zoom range D40/D40X can give users with these four basic lenses. As shown in figure 1, a complete picture can be obtained at 18mm by using any one of these four lenses, and the field of view of each lens in telephoto is internally marked. As shown in Figure 2, it is an enlarged view of the field of view of the longest focal ends of the four lenses, which are 55mm, 70mm, 135mm and 200mm respectively. Improve your ability. Users may take many good photos with basic headphones, but sooner or later, users will find that some images need to exceed the ability of existing lenses. It's time for users to consider adding one or two new lenses to their interchangeable lens library. The main limitations that need to be overcome are as follows. The need to get closer to the theme. Telephoto lenses and telephoto zoom lenses can bring distant objects closer to the camera, so even if the physical distance is far away, it will not be a big obstacle. Users can take compact V-shaped pictures of geese in front of the blue sky, shy tigers in the zoo or fierce sports scenes opposite the football field. Such a lens can highlight the main body and shorten the distance between objects. In the D40/D40X, the long focal length lens covers the range of 55-500mm, and users can also purchase ultra-long focal length lenses to enlarge this range. The desire for a broader perspective. Wide-angle lens or wide-angle zoom lens allows users to shoot a vast landscape, or shoot everything in a room with no retreat, while emphasizing the prospect. The wide-angle lens range of D40 and D40X is about 10-20mm. Approaching the appeal. Macro lens is a special kind of lens, which has close focusing ability and can focus on objects 2.54cm or 5.08cm away from the front of the lens. Some of these lenses are fixed-focus lenses (zoom is not allowed), such as 60mm and 105mm macro nikkor lens, and some are zoom lenses with macro function. At the time of writing this book, although the current 60mm f/2.8Micro-Nikkor lens is an autofocus lens (non-AF-S), it cannot be autofocused on the D40/D40X, but this is not entirely a disadvantage, because users usually use manual focusing when taking macro photos. On the other hand, the latest 105 mm f/2.8 G ED-IFAF-S VR micro nikkor lens provides autofocus function, but an old, similar lens cannot autofocus (users must always pay attention to the word AF-S in the lens name when buying a new lens). The necessity of low illumination shooting or high-speed shutter shooting. In very dark light, the aperture of f/4.5 may not allow users to take pictures at the shutter speed they can hold. In this case, users can use a lens with anti-shake function to improve the ISO sensitivity to an acceptable level without using a tripod, or they can install a lens with a fast aperture on D40/D40X (f/ 1.2-f/2.8). If you need to use a high-speed shutter to take moving photos, users will find that a fast lens is very useful even in good light. The motion capture ability of f/2.8 lens is 1/500s, which is much better than that of f/4.5 lens. The need for clearer images. Some shots are really clearer than others. When shooting may need to cut a lot or enlarge the display, such as enlarging it to about 28-35cm, users will definitely want a very sharp lens. Some lenses have better large aperture, some have better macro, and some zoom lenses have better focal length. When sharpness is the key, the right lens will be of great help to users. The temptation of special functions. When the user's work is very special, the special lens that can be used is likely to help the user complete the work well. This book has introduced the super performance of macro lens in macro photography, and the demand for fast large aperture lens shooting with high-speed shutter in dark light. Anti-shake is another special function that is gradually going to the public. It can compensate the camera and photographer's jitter when taking pictures by moving inside the lens. Some lenses have special abilities that other ordinary lenses don't have. Including some lenses with movable parts inside, which can control the viewing angle to a certain extent, and Nikon's DC lens series (unfortunately, they are all non-AF-S lenses and cannot focus automatically), which allows users to adjust the appearance of parts outside the focus of the image (which is particularly useful in portrait photography). Other special lenses include fisheye lenses and ultraviolet lenses for special science. If the user needs these special functions, no other lens can complete the work.