What does the focal length conversion factor 1 6 mean in a DSLR camera?

The focal length conversion coefficient is going to start from the frame The previous film SLR cameras used 135 film, the size of this film is 36x24mm, and later the digital SLR began to popularize, using image sensors instead of film, but manufacturers found that the cost of making such a size of photosensitive elements is very high, and most consumers may not be able to afford it, so in the production of such a large-size photosensitive element, it also produces small-size photosensitive elements, which is now the mainstream APS-C format camera, For example, 550d and 60d. The conversion factor is one of the problems that arises when the frame size is smaller. For example, if the focal length of the lens is 10mm, and the lens is mounted on 60D, the landscape captured is equivalent to the effect of being shot with a focal length of 16mm on 5D.

Since most of today's digital cameras have a sensor sensor smaller than the 135 format of traditional film cameras, the equivalent focal length of a digital camera lens is much larger than the actual focal length of a 135 camera lens. To illustrate this difference, the concept of focal length multiplier was introduced. If a standard 50mm lens is mounted on a DSLR camera with a focal length conversion factor, the actual focal length is 75mm.

Therefore, the smaller the sensor of a digital camera, the greater the focal length conversion coefficient of the lens.

Nowadays, high-end full-frame cameras have a CMOS that is as large as a traditional film camera, so the conversion factor is 1

The larger the area of the sensor sensor, the better for **imaging.

How many times optical zoom is to divide the maximum focal length by the minimum focal length, for example, 18-55 is 55 18 3 times.

18-200 is This lens is marked on the back is to indicate that the lens is stabilized, so that the longest focal time is not less than 1 20 seconds when the shutter is not less than 1 20 seconds is generally OK, if it is not with is 1 200 or more handheld, it can.

The lens of the SLR is the most important factor in determining the image quality, not as simple as the card camera, even if the same focal length ** up and down will be several times or even more than 10 times the difference, mainly because the internal structure is different, the imaging effect is different, 55-250 imaging effect is worse than 18-200.

So it's cheap.

The lens of the 18-200 that likes to travel is better than the 18-55 plus 55-250, and one lens is convenient for imaging and better.

If you are more in pursuit of image quality, you can choose 15-85 plus 70-200 f4 is hehe, but ** is expensive again.

By the way, 450d won't it be a product from a few years ago and now this ** should be 650d don't be fooled.

Canon half-frame SLR.

DSLR cameras are available in full-frame and half-frame. The image sensor size of the half-frame computer is smaller, so the picture coverage area is smaller. For a Canon SLR, this is equivalent to the coverage area after the focal length of the full-frame SLR. So there is this focal length conversion factor.

For Nikon, this coefficient is .

This camera of yours is a digital camera, not a film camera, so there will be problems with the focal length conversion factor.

This is because due to cost considerations (digital cameras are sensitive by the sensor sensor, the larger the chip, the higher the cost), the current image sensor of most digital cameras is smaller than the 135 35mm full-frame camera (that is, the traditional 135 film camera) of the photosensitive size, so the equivalent focal length of the digital camera lens is much larger than the actual focal length of the 135 camera lens. To illustrate this difference, the concept of focal length conversion coefficient was introduced. The focal length conversion factor is calculated as the ratio of the diagonal size of the 135 film (or full-frame camera sensor) to the diagonal size of the digital camera's sensor.

The size of the 135 film is 36*24mm, and its diagonal size is, and the size of the sensor of your digital camera is about, and the size of its diagonal is, so the focal length conversion coefficient of this camera is divided by, which is approximately equal to. So if this camera is equipped with a 50mm prime lens, it is equivalent to the 80mm focal length of a 35mm full-frame camera. Therefore, the smaller the sensor of a digital camera, the greater the focal length conversion coefficient of the lens.

For DSLR cameras, the focal length conversion coefficient can reflect its grade to a certain extent. At present, DSLR cameras with a focal length conversion factor of or 2 are generally low-end products, while DSLR cameras with a focal length conversion factor of or 1 (i.e., full-frame) are mid-to-high-end products.

APS-C [Nikon Sony Pentax*; Canon*

aps-h【*

m4/3【*2】

One inch [*The focal length only represents the angle of view, and has nothing to do with the distance.

The concept confuses pro.

There is no correlation between the focal length and the actual distance.

Calculation of conversion factors.

So where does this coefficient come about? Take Nikon's SLR as an example, for example, a 50mm lens is installed on Nikon's non-full-frame SLR, and the actual angle of view is smaller than that installed on Nikon's full-frame SLR, which feels like the angle of view of a full-frame SLR with a 75mm lens, and there is the "focal length has changed" that people often mention, in fact, the focal length has not changed, but the angle of view is small, and I mistakenly think that it has changed. By analogy, the same full-frame lens will change by multiple times when mounted on a non-full-frame and full-frame DSLR.

In the same way, Canon's full-frame lens changes before and after mounting on the non-full-frame and full-frame SLR bodies, and the other special one is the 1D series.