Traditional Culture Encyclopedia - Photography and portraiture - How to solve the problems in taking pictures?

How to solve the problems in taking pictures?

All photographers occasionally encounter some problems when taking pictures, sometimes because of equipment failure and sometimes because of human error. The following is the knowledge I brought to you about how to solve the problems encountered in taking pictures. Welcome to reading.

First, the camera/lens problem.

Part of the picture is blocked by a hood or filter. Use the appropriate type of hood that matches your lens. The hood is designed according to the focal length of the lens. If the hood is too long for your lens, it may extend too far and block the picture. Halo may occur when multiple filters are used or filters are used together with a hood, especially when a short focal length lens is used. If necessary, you can take off the hood and cover the lens with your hands. Make sure your hand is not in the photo.

There is dust on the photosensitive element during exposure. A little dust on the photosensitive surface will affect the arrival of light during exposure. When replacing the lens, keep the body clean by blowing the ball or dust cover. Black spots can be erased in the process of image editing, and can also be removed by silver plating or bleaching technology.

Dust on the scanner glass during scanning. Dust on the negative or scanner glass will prevent light from passing through the negative, thus showing white spots on the positive film. Dust on opaque objects or images in the scanner will show dark spots. In digital images, these defects can be modified later, but it is more convenient to keep things clean.

Second, the exposure problem.

The exposure meter is influenced by the background. When shooting an object with a bright background (such as a bright sky), if the whole photometric reading is used, the subject is likely to be underexposed and too dim. If your subject is small and bright and your background is large and dark, you will encounter similar problems. The subject will be overexposed and too bright. Move the exposure meter to the subject, and manually set the aperture and shutter data according to the photometric results. The exposure meters of some new cameras can avoid this situation. They use a variety of photosensitive modes to compare the light conditions in different parts of the scene and automatically adjust the exposure.

Thirdly, the problem of clarity.

The focus of the camera is not aimed at the subject. For example, the object moved, but the camera did not refocus. When using an autofocus camera, there is probably not enough time for the camera to adjust the focal length before exposure.

This camera is completely out of focus. For example, when taking a close-up, the lens is inexplicably focused in a far place. It may be because when shooting with an autofocus camera, there is not enough focusing time for the camera system before exposure.

In many cases, it is caused by camera shake. When shooting with a hand-held camera, the shutter speed is too slow, which will blur the whole photo. According to experience, when shooting with a hand-held camera, at least the lens focal length value should be used as the slowest acceptable shutter speed:1-100 mm seconds for a 000mm lens and 1/250 seconds for a 200mm lens. Try to use a tripod when shooting with a slow shutter.

The lens is too dirty. This will generally reduce the sharpness of the picture, especially when it occurs at the same time as lens halo.

Insufficient depth of field. If the aperture is too large, the depth of field will be small, and some parts of the scene focused by the camera will be clear, but the foreground and background will be blurred. Motion blur. The rest of the picture is clear, but the moving object is not real.

Fourth, the color problem.

The shooting scene is a fluorescent light environment. The fluorescent lamp device emits a lot of green light, which makes the whole scene look green. This problem can be solved by assembling FL fluorescent lamp filter on the lens.

The white balance adjustment is not correct (digital camera), or the color film does not match the light type. RAW files can adjust the white balance without losing image quality, but JPEG and TIFF formats cannot. Film type: use tungsten lamp to balance the film. Shooting in sunlight or flash will make the scene blue, so use sunlight to balance the film. Shooting with the sun balance film in tungsten lamp will make the scene red, so shooting with the balance film in tungsten lamp should be done in tungsten lamp.

The reflected light from nearby colored objects will cause color cast in the scene. Shooting portraits in the shade of trees will make the skin look unexpectedly green, because the light is filtered by green leaves. Similarly, the pictures taken by the wall reflection with obvious color will also show the color of the wall. This effect is remarkable in skin color or neutral colors such as white and gray.

The shooting scene is a fluorescent light environment. The fluorescent lamp device emits a lot of green light, which makes the whole scene look green. This problem can be solved by assembling FL fluorescent lamp filter on the lens.

Verb (abbreviation of verb) flash problem

Light reflected from a reflecting surface. When shooting directly at the surface of a glass window, mirror, book or shiny wall, if the flash is on or near the camera, it will reflect the light back to the camera lens. When shooting in a scene with a reflective surface, move the camera or flash to one side, so that the shooting axis or light path forms a certain angle with the reflective surface. Glasses will have the same problem, so make the subject's line of sight slightly deviate from the camera, or take the flash off the camera.

Red light reflected from the vascular retina. Take people's eyes away from the camera, or take the flash away from the camera. Some cameras have a red-eye reduction mode: turn on the flash before the main exposure process, thus avoiding the iris of the subject and reducing the amount of visible red light.

The angle of the flash will produce unnecessary shadows. Draw a virtual line between the flash and the subject, which helps to predict the position of the shadow. You can also place a low-power tungsten lamp near the flash, which is also the role of this kind of modeling lamp in the flash device of large studios. Or keep the subject away from the wall and let the shadow fall on the ground outside the film frame, instead of appearing on the wall obviously.

Use a flash in strong light. This phenomenon is easy to occur when the scene light is bright and the camera shutter speed is slow. In the process of opening the shutter, two images will be recorded when the film is exposed-a clear image under a short flash and a fuzzy ghost under a bright light. Make sure that the shutter is set to the maximum adaptive speed of the flash. Depending on the situation, you can also dim the spotlight and shoot when the subject is not very dynamic, or shoot only with the spotlight under the high-speed shutter.

Different parts of the original scene are at different distances from the flash. The part far away from the flash is darker than the part near the flash, because the longer the propagation distance of the light emitted by the flash, the weaker the intensity. Try to gather the important parts of the main body and keep them close to the flash.

Cameras with focal plane shutters, such as SLR cameras, have too fast shutter speed. When the flash is triggered, the shutter has not been fully opened. If you set the shutter speed manually, please refer to the manufacturer's guide to learn how to set the camera when using the flash. For most cameras, 1/60 seconds is safe enough, and some cameras can set a higher shutter speed when using the flash. Flash shutter synchronization speed may be marked with different colors, which are different from other values. Or it can be marked with an X-shaped or flashing symbol. If the camera automatically sets the shutter speed when using the flash, then your camera needs to be repaired.

If the subject is too dark, it means that the scene is underexposed-the light that illuminates the subject is too weak. If the exposure is set manually when the flash is used, it may be caused by the incorrect aperture setting of the camera lens or starting the shutter before the flash is fully charged. In manual mode, shooting outdoors or indoors in a large space (such as a gym) at night can increase one exposure. In other cases, dark scenes that absorb ambient light may increase exposure.

If the subject is too bright, the scene is overexposed-the light shining on the subject is too strong. In some cases, overexposure in manual mode is caused by the wrong aperture setting of the camera lens. In manual mode, when shooting in a small room or a color room, the aperture can be reduced by one grid to balance the excess light reflected from the wall and ceiling.

Six, the problem of digital photography

The image resolution is too low for the intended use. For display, 72 ~ 100 PPI is more suitable, and inkjet printers or thermal printers need 200 ~ 300 dpi. If you scan an image, you need to set a resolution higher than the above purpose. If the picture is from a digital camera, try to improve the resolution in the "Image-Image Size" column in Photoshop. The so-called cubic smooth difference method is selected. Next time, you should use a higher resolution.

The picture quality of digital cameras is too poor. In the low image quality setting (basic or good image quality), the camera sets the image to a low resolution or compressed image. Details will be lost when the compressed picture is reopened. When printing small photos, the results may be negligible. However, when printing large photos, the loss of image quality will be very obvious. Plan the final size and production method of the photo. Web photos can be stored with low quality. If you want to print 8 x 10 or larger photos, you need to set the camera to the highest quality.

This situation often appears in the shadow area of photos taken at night, or exposed for a long time in poor light. Try shooting with a lower ISO setting. Try ISO 100 or ISO 200 instead of ISO 800 or ISO 1600. In Photoshop, try the function of "filter-noise-speckle removal". This method can really reduce the noise, but it will also soften the picture. Some software and Photoshop plug-ins may have better denoising effect.

When shooting with a digital camera, it may be because the ISO is too high. Try to shoot this scene with a lower ISO. You may need a tripod, or a slower shutter speed, or a flash and extra indoor light. Sometimes some stripes will appear immediately, and the shooting effect with existing lighting will be better than with extra lighting and flash. At this time, we must improve the ISO sensitivity.

Digital images are too sharp in image editing software. If the sharpness of the original file is not artificially improved, return to the original file for operation. If you need to increase the sharpness, you can reduce the sharpening intensity.