I'm a camera idiot. Did I just buy a SLR camera, Nikon D90? I want to ask some questions so that I can understand them as easily as possible. thank you

"Idiot" will buy a SLR as soon as he gets started, with a high starting point and support!

The whole photography introductory course should be as popular as possible!

1, the first question is equivalent to three questions, separate.

If the lens is equivalent to a window, the aperture can be understood as a curtain, and the amount of light entering the room can be adjusted by control; When the curtain is opened, more light enters the room, and when it is opened, less light enters the room. Furthermore, the marked value of the aperture on the camera lens is an inverse, that is, aperture 4 means that the light input is 1/4, and similarly, 8 means 1/8, that is, the larger the value, the smaller the light input is.

When the aperture increases (the mark value decreases), the depth of the scene of the photo is most widely used in portrait shooting, and the people are clear, while the background is blurred. Even some professional portrait heads can make the focused eyes and eyelashes clear and sharp, while the other eye is virtual. On the contrary, if you reduce the aperture (increase the mark value), the depth of field of the photo will be very large, which is the most commonly used when shooting landscape films, and the scenes from far to near are very clear. The so-called "depth of field" actually refers to the size of the clear distance before and after the focus (the position you want to see clearly).

Aperture can control not only the depth of field, but also the flash, because the flash synchronization speed of each camera is basically determined, such as 1/60,1125, 1/250 seconds and so on. Speed means that there is a device called shutter behind the curtain, and the amount of light entering is controlled by its opening and closing time. This opening and closing time is generally expressed by the reciprocal of seconds, which is called "speed". When taking pictures, besides aperture, speed is another important factor to consider. Its marked value is the same as the aperture, and it is also in the form of reciprocal. 30 means 1/30 seconds, and 500 means 1/500 seconds. ........................................................................................... In general, the flash is only related to the aperture within the synchronous speed range. If people are close, the aperture will shrink, and if people are far away, the aperture will open.

2. Manual exposure refers to manually adjusting the combination of aperture and shutter. Assuming that the aperture is 5.6, the speed is 125, and the photo exposure is normal, the film with accurate exposure can also be obtained by enlarging the aperture and speeding up, or reducing the aperture and slowing down. In the previous example, you can also open the aperture to 4 and increase the speed to 250, or open the aperture to 8 and decrease the speed to 60. The reason why it is manual is to control the depth of field, and the other is to reduce the photo blur caused by the slow shooting speed of the hand-held camera (in general, the shooting speed of the hand-held SLR should not be lower than 1/60s). The specific operation is slightly different from camera to camera. Select the mode on "M" and you can manually adjust the aperture and speed.

3. Sensitivity is to control the sensitivity of the sensor chip on the digital camera, which is expressed by ISO. Increasing the ISO value can improve the sensitivity of the sensor chip (CMOS or CCD) to light, that is to say, a photo with accurate exposure can be obtained with a small amount of light, that is, a photo can be taken in a very dark environment, but the negative effect is that the noise of the photo will increase. If the ISO value is low, the image quality will be much better, but it takes a long exposure time, which is also one of the reasons for increasing the noise of photos, so the available adjustment range of ISO will not be too large, generally between 100-800 (except for high-end machines).

4. Take pictures at night If you want to take clear pictures of people and the colored lights behind them are beautiful, you need a tripod or find a place where you can put your camera smoothly. Of course, it would be better if your arms were steady enough.

First, measure the correct exposure combination (you can use aperture and P file first) without shooting the background, and write down this numerical combination, such as 2.8-30. Then determine the position of the person, turn on the flash, and determine the aperture number according to the distance between the person and the camera, such as 2 meters 5.6, 2.5 meters 4.0, and 3 meters 2.8 (the flash index of the flash is different, so this value is different, please see the manual). ......

Pop up the flash on the top of the machine or connect it externally. Manual exposure can be used at this time. Choose the aperture number according to the distance of people, such as 5.6. Adjust the speed to 1/8 seconds according to the exposure combination value just recorded. Focus, compose, and press the shutter. All right!

Another question you didn't ask is attached:

After determining the correct exposure combination, the aperture is reduced by one step, the speed is increased by one step, and the exposure is unchanged; In the same way, the aperture is opened by three gears, the speed is reduced by three gears, and the exposure is the same.

The first change of aperture is (from big to small):

1.0、 1.4、2.0、2.8、4.0、5.6、8.0、 1 1、 16、22、32、44、64 ......

The first speed change is (from slow to fast):

30'、 15'、8'、4'、2'、 1、2、4、8、 15、30、60、 125、250、500、 1000、2000、4000 ......

Where: 30' means 30 seconds, 2' means two seconds, and the number without apostrophe means 1/n seconds. ......

Some lenses have values between the above two levels, such as 1.2, 1.8, 2.5, 3.5, etc. These are called half levels, and so is speed. ......

Finally finished coding, so many words, not easy, applause!