Today, I will share with you a dark function on the camera. Why is it called the dark function? Because he is almost never used by us, but if there is a need, its existence is very important.
If you are a Canon camera, then look carefully, there is a very inconspicuous little dot on the camera, probably at the bottom right or bottom left of the camera, there is a small black button, there is no logo on it, but some cameras have it There is a logo on it. For example, a Nikon camera has a pv logo on it. But if it doesn't have this logo like a Canon camera or other cameras, what is the function of this key?
It's actually the camera's depth-of-field preview button. Depth of field preview is the factory setting of Nikon, and you can set the PV key to the function you need through custom settings. This is a function unique to our SLR, called the depth of field preview button. The depth of field preview is used to observe the depth of field range of my current framing. Why is there this button? We have to pay attention that because our camera is actually in the normal shooting state, it will always maintain the state of the maximum aperture, for example, like a Canon camera, no matter the aperture is set to 11, 16, 22, no matter what the aperture value is set to , the aperture is always the largest state, I have no way to observe the current depth of field, but you can know the depth of field state of the camera by pressing my depth of field preview button, then you can take a look after opening the cover, if If you say the camera has no reflections, look carefully in front of the lens, if you don't press the depth-of-field preview button and press the depth-of-field preview button, there is a clear difference. We can observe the depth of field preview in the camera, the aperture ring of his camera is shrinking. If you press the pv button, the lens aperture will shrink to the aperture value you set, and you will find that the viewfinder dims instantly. This is because during normal framing, the camera will automatically expand the lens aperture to the maximum to obtain more light, making the viewfinder bright and easy to focus. This function is not very useful in daily shooting. Only when using a macro lens, it is easier to adjust the aperture value by pressing the depth of field preview to observe whether the subject is completely clear and within the depth of field range.
Why press the depth-of-field preview button?
The main reason is to facilitate our screen to focus, because we know that the focus of the SLR is a passive focusing system, it needs to receive enough light to be able to focus completely and clearly, in order to ensure enough light is received, so he automatically Keep it at the maximum aperture at all times. Only when you press the shutter moment will your optical fiber shrink to the value you set. Therefore, if we usually want to shoot, if the depth of field requirements are particularly high, we must Note that we have to press our depth of field preview button to make an ultimate judgment of depth of field.