The trouble of a novice SLR, how to convert the focal length when choosing a lens?

Let the people who do the yellow net advertisements die.

The conversion coefficient of D80 is that the CCD of the 35mm camera (traditional film and the current full-frame picture are) is 36*24mm, and its area is multiple of the area of the D80 CCD, so the focal length of the actual equivalent to the 35mm camera should be multiplied by this coefficient, 16-85mm is equivalent to the difference in your statement because the CCD area of different brands of cameras is different, and the coefficient is also different. So it depends on the explanation, and it cannot be generalized.

In fact, except for the full-frame DSLR camera (the CCD area is 36*24, the coefficient is 1, no need to convert), the rest of the lens has to be converted by a coefficient.

16-85 is more suitable for you, the focal length below 35mm is the wide angle, the wide angle of 16* is okay, the angle of view is too large and easy to deform. At the same time, the telephoto has 85*, which is also considered a medium focus, and it is better to shoot portraits. Of course, when choosing a lens, pay attention to the maximum aperture as wide as possible, preferably or.

It's good for blurring backgrounds. Of course, telephoto can also solve this problem.

The 24-120 is suitable for telephoto, if you just shoot your son, you don't want that, the imaging quality is definitely worse than the former. Unless the ** bit is circled in red. Generally, lenses with large optical zoom ratios have poor imaging than lenses with small magnifications.

The equivalent focal length of 16-85 is.

The 24-120 equivalent focal length is 36-180 The equivalent focal length of the former is about the same as the physical focal length of the latter If the latter is easy to use, why does Nikon have a 16-85.

All SLR lenses are marked with physical focal lengths, so it is better to multiply 16-85 on the D80 You can look at the sample on the Internet 14-120 becomes 36-180 on the D80 The disadvantage of not having a wide angle is that you have to step back a little when shooting big scenes, and you have no choice but to retreat on some occasions.

You can look at the 18-105 image quality is worse than the 16-85, but ** is also cheaper, and the rest of the money on the header is still with you.

It's not the lens that decides, it's your fuselage, as long as it's not a full-frame camera, you have to take it, although I haven't used Nikon, I use EOS5D, I don't need to ride.

In fact, when you shoot your son, the focal length is not an important parameter, and you don't have to worry too much about the wide-angle distortion, I often use the 24mm wide-angle portrait (and it is the actual focal length of 24mm, and the full-frame camera does not need to multiply the coefficient), as long as the character is not placed on the edge of **, the distortion is acceptable, and it seems that there is another charm. The key is to have a wide aperture of the lens, so that the shutter speed is fast and the children who are jumping around will not be confused.

After you play DSLR for a while, you will find that what you care about is not the problem of focal length at all, but the full frame and large aperture, and then, a fixed focus head is done, and the image quality is ...... than the zoom headThere are improvements that you can see.

You multiply the focal length of the lenses you want to buy by their equivalent focal length on the camera.

The equivalent focal length of 135 on the D80 for all lenses is multiplied by the difference between the lens and the full-frame lens, which is a small image field, but the conversion of focal length is the same.

These two heads are about the same grade, but it is generally agreed that 16-85 is better. If you don't go to full width in the short term, it is recommended to go up to 16-85. Moreover, 24-120 has no wide angle, and even if you enter another silver angle, the wide angle end is still only 18.

At the telephoto end, the 85 can be both portrait and landscape.

So, based on your needs, I think you should go up to 16-85 first, and then you can go up to 70-200 later, and you can fight the world with two heads!

Take Fujifilm GFX50R as an example, X is the size of the GFX machine, the diagonal is X+, and the square is defined by Pythagorean).

135 full-frame diagonal, G32-64 lens focal length equivalent to full-frame 32, 45 lens equivalent to <>

Lens focal length refers to the distance from the principal point of the optical back of the lens to the focal point, and the focal length of the lens is a very important indicator of the lens.

How to calculate the focal length of the lens:

Focal length is a measure of the concentration or divergence of light in an optical system, which refers to the distance from the center of the lens to the focal point of light concentration in the focal length of a parallel lens. It is also the distance from the center of the lens to the imaging plane such as the film or CCD in a camera. Optical systems with short focal lengths have a better ability to concentrate light than those with long focal lengths.

The length of the focal length of the lens determines the size of the subject imaged on the imaging medium (film, CCD, etc.), which is equivalent to the scale of the object and the image. When shooting at the same target at the same distance, the image with a long focal length is larger, and the image with a short focal length is smaller. Depending on the application, the focal lengths of camera lenses vary greatly, ranging from a few millimeters to a dozen millimeters to several meters long.

The focal length of a lens is divided into image-square focal length and object-square focal length. The focal length of the image square is the distance from the main surface of the image square to the focal point of the image square, and similarly, the focal length of the object side is the distance from the main surface of the object to the focus of the object side. It is important to note that due to the extensive use of telescope structures in camera lens design, especially in zoom lenses, the focal length of the object and the focal length of the image are not necessarily equal.

When we talk about the focal length of a camera lens, we mean the focal length of the image square.

1.Focal length.

Focal length refers to the distance at which a parallel ray of light is focused after passing through a lens or group of lenses, as shown in the figure below

As you can see from the diagram, the focal length of the convex lens is 10 cm.

2.Imaging.

When the distance of the object changes, the light emitted by each point on the object is no longer parallel rays, and in order to get a clear image, the distance of the lens to the film (light screen) needs to be adjusted, as shown in the figure below

Regardless of the actual distance from the lens to the optical screen, the focal length of the lens is constant.

3.Zoom.

When the isofocal length is adjusted from 70mm to 200mm, the distance representing the convergence of parallel rays becomes 200mm, that is, the film is far away from the lens, so the image will be magnified according to the scale, see the figure below:

All of the above ** are from the Internet).

Focal length refers to the distance from the optical center of the lens to the imaging surface. The higher the distance value, the larger the enlargement of distant objects, and the smaller the value, the larger the shooting angle and the larger the shooting range.

Lens focal length: refers to the distance from the principal point to the focal point after the lens optics, which is an important performance indicator of the lens. The length of the focal length of the lens determines the size of the image, the size of the field of view, the depth of field and the perspective strength of the image.

Bigger is not better. It depends on your needs. The 18 55 belongs to the wide-angle short-focal length zoom, which is suitable for shooting landscapes, for example, if you are standing on a mountain and want to capture a larger area of scenery.

The latter belongs to the wide-angle medium focus, that is, in addition to the large framing angle, it can also be extended to the medium focus, for example, if you are 5 meters away from the subject and want to see a larger subject on **, you can position the lens at 105, which is equivalent to 6 times that of 18mm.

Above 200mm is a telephoto, which can zoom in on a farther view, such as a bird from ten meters away.

Specifically, 18mm is equivalent to everything you see when both eyes are open and looking ahead. 100mm is equivalent to what you see with one eye closed (much narrower than two eyes, right?). ）

200mm or higher means that you are using a telescope to see an object, and something far away passes through the telescope as if it is in front of your eyes or pulled very close. It's a truth.

The reason why there is a zoom ratio of 18 55 or 18 200 is that 18 200 is used more than 18 55, because the former has 55 200 more than the latter.

Not necessarily.

The imaging effect of fixed-focus in a DSLR lens is better than that of zoom.

For example, when shooting people, it's best to shoot with a fixed focus.

If you shoot birds or perform. If you need a certain distance to shoot in sports, you will need a zoom lens.

The higher the value you say. The farther you shoot, the greater the distance.

First of all, it is necessary to understand what the purpose of choosing a lens is. Is it scientific research or photography? If it's photography, it's not that way of thinking.

If you want to do landscape photography, it is best to have a 14 35mm focal length lens, which is called a wide-angle lens.

If you can shoot portraits, documentaries, etc., you can use a 50 85 focal length lens, this kind of lens is called a medium focal length lens. 50mm is called the standard lens.

If the focal length is 105 300mm, it is called a medium telephoto or telephoto lens. Above 300mm is called a super telephoto lens. These shots are taken in close-ups, and the long shot cannot be close to the object.

Finally, the focal length of the above lenses is obtained with the full-frame body, and if it is a CMOS of other sizes, it must be considered separately. For example, a medium format 90mm lens is a standard lens.