How does the zoom lens prevent the imaging deformation during photography? For example, how to calculate the aperture value of indoor photography flash, and whether to make exposure compensation?

1. Focus with a long focal length. When using zoom lens, the correct focusing method is to focus with a long focal length first, and then choose the appropriate focal length to shoot; Because under the long focal length, the image of the subject is the largest and the depth of field is the smallest, which is convenient for accurate focusing. In the case of backlight or complex light, it is also helpful to choose appropriate partial metering, and it is not necessary to be close to the object for metering. Usually, when shooting, we often use a zoom lens with medium and long focal length as the main lens, focus on metering with the longest focal length, and then select the ideal focal length after locking the exposure, so that we don't have to move back and forth.

2. Try more at each focal length. Although most photographers are extremely concerned about the zoom magnification of the zoom lens, they often use the long focal length at one end, and some even regard it as a fixed-focus telephoto lens. In fact, when you try to use other focal lengths to get a completely different picture, you will find that the zoom lens has considerable potential as a variable framing tool.

3. Be familiar with the operation of zoom lens. In the early zoom lens, zoom and focus were adjusted by two rings respectively. At present, most zoom lenses are changed to single-loop control, which is characterized by changing the focal length by pushing and pulling the lens back and forth and rotating it left and right. Therefore, for photographers who have just bought a new mirror, they should be familiar with and keep in mind the front and rear direction of zooming and the left and right position of focusing, so as to avoid the influence of slightly turning the adjusting ring when zooming after precise focusing. This is why many more "conservative" photographers prefer to use the old-fashioned double-ring zoom lens.

4. Correct use of the bracket. When using a zoom lens with a focal length of more than 200mm, the lens should be fixed on a tripod and other brackets to ensure the stability when shooting.

5. Choose the right hood. Zoom lenses are more prone to halo than other types of lenses, so a suitable hood is essential. Sometimes the occlusion caused by the hood can't be seen in the viewfinder of a single-lens reflex camera, but it is displayed on the display screen. This situation is most obvious when shooting in a small aperture, which often causes the hood to fall into the depth of field. In addition, some hoods are effective at the long focal length end, but when zooming to the short focal length end, there will be vignetting caused by occlusion that cannot be seen on the viewfinder in the photo. Therefore, it is very important to choose a suitable hood for the zoom lens and use it reasonably.

6. Add a range finder. If you need to use a long focal length, you can change your 70-2 10 mm lens into a telescopic zoom lens of 140-420mm at will for a little money, and the triple zoom lens can even reach 2 10-630 mm, so that your lens can immediately rank among the astronomical telescopes. But the price will be the loss of aperture series and the clarity of the photos taken.

For example, if a F4 zoom lens is equipped with a 2x rangefinder, the aperture will lose 2 levels and become F8; After adding 3 times the range finder, the maximum aperture becomes F 1 1. As you know, the best resolution of the lens should be to choose an aperture 2 levels smaller than the maximum aperture to shoot. Therefore, when adding rangefinder, we must consider using high sensitivity and tripod, and at the same time, the subject should be still.

7。 Use the filter carefully. Don't add a filter to the zoom lens unless it is really necessary. You really need a protective glass on the beach or in salt water. In order to change the color temperature and create special effects, such as deepening the color of the sky and eliminating reflection, polarizers are needed. In addition, adding some optional filters will only increase the reflection problem inside the lens, which is already a headache.

8. Control the depth of the picture. Shoot with a zoom lens at a distance of 1.5 meters, with a focal length of 60mm, and shoot at a distance of 7.5 meters, with a focal length of 300 mm. The images of the subjects in the obtained photos are the same size, but the depth of the two photos is different. Photographs taken with a focal length of 60mm have a sense of depth and space in the background; 300mm focal length shooting gives the impression that the scene is compressed and the subject and the scene seem to be "closer".

9. Keep a distance to prevent deformation. When shooting with the wide-angle end of the zoom lens, attention should be paid to keeping a proper distance from the subject to avoid deformation of the subject. It must be remembered that the main factor affecting the perspective effect is the distance when shooting, not the focal length.

10. The trick to control the depth of field. You can do an experiment. You can use the same aperture and the same focal length to take two photos with the same distance of 25mm and 50mm respectively, and then enlarge the photos with the focal length of 25mm to make the subject in the picture as big as that of 50 mm. After comparing the backgrounds of the two photos, it will be found that the background in the enlarged photo is not as hazy as that in the first photo, and actually a more useful depth of field is obtained. This method is also effective when applied to fixed-focus wide-angle lenses.