Related problems of camera and lens

Category: entertainment and leisure >> camera

Problem description:

I know that the aperture of a camera refers to the amount of light entering, and I also know that focusing refers to seeing what you want to shoot clearly.

But I want to ask some basic questions.

For example, people say 5mm camera or 125 camera. What do these 5mm and 125 mean? What's the use?

Why is the standard lens focal length of a 5mm camera mostly 40mm, 50mm or 55mm? What do 40mm and 50mm mean here?

Others say how many millimeters the lens has, and this millimeter refers to the focal point of the lens (CCD chip

) distance? So what is the diameter of the lens glass? Is there any relationship and requirement between lens diameter and camera? Is it better to have a larger lens diameter or a smaller lens diameter? What difference will it make?

Also, I want to know whether a large lens (with a lens diameter of 80mm and a lens length of 120mm) can be compared with a small lens (with a lens diameter of almost 15mm and a lens length of about 25mm), and what is the difference between the two effects? The manufacturer told me it's all the same, right? What should I pay attention to? What are the requirements of these two lenses for the camera?

As an amateur, I don't know how to ask such a long question. I hope you can give me some advice. To put it bluntly, I am stupid. Ha ha. Thank you.

Analysis:

It's rare to have such a long question. I'll make a long story short and explain:

1, I have never heard of "5mm" and "125" cameras, only 35mm cameras, 135 cameras, 120 cameras and other cameras with frames. As far as picture frames are concerned, 35mm camera and 135 camera belong to the same category, which is the tradition that we use most in our daily life. The sheet size is 24mm X 36mm, mostly in the form of packaging, generally 36 sheets. Because this film is called 135 film, our common camera is also called 135 camera. There is also a saying that the 135 of the 135 camera is actually the serial number given to 35mm film by Kodak, so there is this 135.

2. The standard lens focal length of135 camera is 50mm. This is because the viewing angle of a lens with a focal length of about 50mm is basically the same as that of the human eye. Therefore, a lens with a focal length of about 50 mm is called a standard lens, a lens with a focal length greater than this is called a telephoto lens, and a lens with a focal length less than this is a wide angle (the shorter the focal length, the wider the viewing angle).

Generally speaking, how many millimeters of the lens refers to the focal length of the lens.

4. The diameter of the lens glass scene is usually described by the aperture. The larger the lens diameter, the greater the luminous flux per unit time, so that you can get enough exposure in a short time. Of course, the lens of the camera uses the aperture to control the size of this aperture, so that it can be combined with the shutter according to the intensity of external light to obtain appropriate exposure. The lens consists of several groups of lenses, and the diameter of the lens must be greater than or equal to the area of the photosensitive element or film, otherwise, according to our middle school physics knowledge, the photosensitive film will not be completely photosensitive. Because the size of ccd, cmos and other photosensitive elements used in digital cameras is much smaller than that of 35mm film, the diameter of the lens is also much smaller.

You don't mean the camera, because most ordinary cameras can't change lenses. What you should say is a digital camera. If the large lens you mentioned is used in a traditional camera, it will not fully play its role, and only the middle part of the lens will be used, but the cost will be high. The lens with a diameter of 15mm can only be used in digital cameras. If it's a lens that matches your digital camera, there's no problem. But the former should be used in traditional cameras or digital SLR cameras, and the shooting effect is better than that of 15mm diameter lens.

That's all you can answer at present. You can spend half a day learning the basics, and many questions will be clearer to you.