Questions and answers on basic knowledge of photography

The photographer's ability is to transform the fleeting ordinary things in daily life into immortal visual images. The following is a question and answer about the basic knowledge of photography that I took with me. I hope it helps you.

Q: What is a digital SLR camera?

Answer: "SLR" camera is the abbreviation of single-lens mirror camera, which refers to the camera structure where the photographer can directly see the image passing through the lens from the viewfinder. There is a reflector between the photosensitive element and the lens of the SLR camera, which reflects the light into the optical viewfinder. When the shutter is pressed, the reflector pops up, so that the light emitted by the lens reaches the photosensitive element. The mirror moves very fast. Even if the shutter height is 1/4000 seconds or 1/8000 seconds, the viewfinder is only blocked instantly.

Q: What is the DX format in Nikon cameras and lenses?

A: Except for some professional cameras, most digital SLR cameras still use the photosensitive elements in APS-C format, which is the so-called "APS-C" format. The size of the photosensitive element in this frame is almost the same as that in the past "APS-C film", and the area is about 23.5 mm× 15.6 mm, so it is generally called "APS-C frame". Nikon calls this specification "DX format".

Q: What is a full-frame digital SLR camera?

A: Most digital SLR cameras are based on the lens of a 35mm camera. Therefore, in order to distinguish it from digital SLR cameras with APS-C format, cameras with the same photosensitive elements and 35 mm film size are generally called "full-frame cameras" and Nikon calls them "FX frames". Compared with the general APS-C format, the photosensitive element area of a full-frame digital SLR camera is 2.2 1 times, so it can take better photos.

Q: What is the small turntable next to the viewfinder for?

A: The small dial next to the viewfinder is used to adjust the diopter of the viewfinder, which is equivalent to the viewfinder glasses, so that photographers with vision problems such as myopia, hyperopia and presbyopia can also use the viewfinder normally. On some cameras, the dial may be hidden by the viewfinder protector (the protector installed on the viewfinder eyepiece). If you can't find the dial, you can try to remove the viewfinder guard. The dial can be adjusted negatively for myopia and positively for hyperopia. Observe and adjust the viewfinder until the objects in the viewfinder are most clearly displayed.

Q: Which effect is better, fuselage anti-shake or lens anti-shake

A: Generally speaking, the correction effect of lens anti-shake and fuselage anti-shake is the same. When the anti-shake assembly is installed in the fuselage, the position of correction operation is located at the back end of the optical system. When the lens is installed, it is located in the center of the optical system. Although the position is slightly different, the adjustment method is more important for anti-shake, so despite the different positions, the effect is not much different. However, from the convenience of use, the "lens anti-shake" that comes with the mirror has more advantages. This is because the correction effect can be observed in real time from the viewfinder when taking a view, and you can wait for the shooting opportunity after carefully observing the subject. This advantage is particularly evident in ultra-telephoto photography with a focal length of more than 400 mm and shooting high-speed moving animals or racing cars. On the other hand, the "anti-shake" of the fuselage is effective for any lens, which can make all lenses have anti-shake effect, which can be said to be convenient and cost-effective.

Q: What does the depth of field preview button do?

A: I saw it in the optical viewfinder when I was shooting. The picture is a picture with the lens aperture fully open. Therefore, if the preview picture in the viewfinder is compared with the actual shot when the aperture is contracted, the background blur and so on will be different. To confirm the depth of field in the viewfinder, you can press the Depth of Field Preview button while looking at the viewfinder. If the photographer narrows the aperture at this time, the picture in the viewfinder will be darkened, but the blur and focus range of the current aperture can be previewed.

Q: Why can't continuous shooting press the shutter after counting?

A: The photos taken by the digital SLR camera need to be processed by the image processor inside the camera before they can be stored on the memory card. Recently, with the continuous improvement of the performance of the image processor, the continuous shooting speed of the camera is also increasing, and the number of continuous shooting sheets is also increasing. However, on the other hand, because the effective number of pixels of the photosensitive element is also increasing, the data amount of each photo is also increasing. If continuous shooting is used, sometimes the data processing speed of the image processor can't keep up. The camera manual will explain the data processing ability of the image processor in the "Maximum Number of Photographs". If it exceeds its processing capacity, the photographer cannot press the shutter and continue shooting, so it is necessary to confirm the data processing capacity of the image processor in advance. In addition, the memory card also has data transmission speed. If the speed is slow, the data storage speed will be slow, and the interval between two shots will be longer. So we suggest using a memory card with faster transmission speed.

Q: Why are some things in the photo invisible in the optical viewfinder?

A: If you carefully observe the photos taken by the digital SLR camera, you will find that the actual range of the photos is larger than that seen through the viewfinder. This is because the range seen through the viewfinder is smaller than the imaging range of the photosensitive element. If the imaging range of the photosensitive element is regarded as 100%, then the ratio of the range seen through the viewfinder to the imaging range of the photosensitive element is called "viewfinder viewing rate". If you want to make the field of view of the viewfinder reach 100%, then the requirements for technical level and parts accuracy are very high, which is generally difficult to achieve. Therefore, only some professional high-end cameras have a viewfinder field of view of 100%, while the standard field of view of ordinary digital cameras is generally 95%.

Q: Why are the four corners of the photo darkened? How can we avoid this situation?

A: One of the reasons for the darkening of the four corners of the photo is the "insufficient peripheral light" of the lens. The lens is composed of several concave-convex mirrors, so sometimes the central part of the picture is very bright and the periphery is very dark, which is the most common phenomenon in zoom lenses. Another reason for the darkening of the corners is the filter and hood. For example, if several filters are installed or the hood is not properly installed, and the lens and hood are not well engaged, the picture will be "missing". This phenomenon often occurs in lenses with a focal length between the wide-angle end and the standard, so you must pay attention when installing filters and hoods.

Q: Is it true that the battery life will be reduced when shooting in a cold place?

A: When using a digital SLR camera in a cold place, the maximum number of shots sometimes becomes very small. This is a temporary phenomenon caused by the drop of battery temperature, not a fault of the camera. In cold areas, not only the performance of rechargeable lithium batteries will be greatly reduced, but all batteries will have this problem. If the battery temperature rises, the performance can be restored, and several spare batteries can be prepared. Put the spare battery in your pocket and change the battery frequently when shooting, which can keep the battery at a certain temperature and will not have much impact on shooting. When shooting in cold areas, besides batteries, we should also pay attention to another problem, that is, condensation. When the camera is taken from a low temperature place to a high temperature place, condensation will occur not only on the surface of the lens, but also inside the camera. To avoid this phenomenon, it is best to put the camera in the camera bag first, and don't touch the warm air directly.

Q: Do I need to turn off the camera power when changing lenses?

A: It is common sense to turn off the camera power when changing lenses. Generally, when a digital SLR camera is turned on, the camera and lens are connected (communication state). Moreover, the power switch also has a reset function, which can not only check the state of the lens and the memory card, but also initialize the anti-shake compensation function. Of course, even if the lens is turned on and removed, the camera will check the state of the lens bayonet, and generally there will be no problems. However, if the camera system is confused due to misoperation, some valuable shooting opportunities may be missed. Therefore, if you have spare time, you should follow the correct "operating rules" to prevent some accidents. In addition, like replacing the lens, it is best to replace the memory card when it is turned off. We still need to be careful to prevent accidents and data loss.

Q: What is the difference between the "normal" and "active" anti-shake modes on the lens?

Answer: "Normal" mode is the most commonly used anti-shake mode, and the jitter in the four directions of up, down, left and right will be corrected. The "active" only makes corrections in the up and down or left and right directions, which is suitable for shooting sports scenes such as racing cars.