Frame and Equivalent Focal Length of Photographic Notes (3)

There is a special knowledge point here, which I almost ignored. Ha, I thought this knowledge point was not important at first, but later I found it was not.

Now digital cameras are divided into Quan Huafu and APS series (half-frame), so what's the difference between Quan Huafu and APS? Use a picture to illustrate it ~

This is a photo taken with a 200mm lens. As you can see, the whole picture under Quan Huafu is wide and complete, while only a part of the picture under APS is in the middle.

Yes, I have. Our camera is an ASP-C half lens. As for the frames of other cameras, I don't know.

Write the equivalent focal length after the frame, naturally because they are related, so I won't write what is the equivalent focal length here.

However, the first thing to be clear is:

As shown in the above figure, the actual focal length is 200mm, the Quan Huafu equivalent focal length is 200mm, and the equivalent focal length in APS-C frame is -300mm.

Why? How to calculate?

What I understand is-equivalent focal length: the focal length relative to the full frame.

In the above picture, we can see that under the same focal length, the pictures taken by Quan Huafu and half frame are different, that is to say, the focal length of the pictures taken by ASP-C frame is 300mm for Quan Huafu.

The lens conversion coefficient of APS-C size sensor is 1.5 (Nikon, Sony, Pentax, Fuji) or 1.6 (Canon), and the actual focal length multiplied by 1.5 or 1.6 is the equivalent focal length of their lens.

The lens conversion coefficient of M4/3 is 2, and all actual focal lengths multiplied by 2 are equivalent focal lengths.

The lens conversion coefficient of 1 inch sensor is 2.7, and all actual focal lengths multiplied by 2.7 are equivalent focal lengths.

Then, I found a very terrible thing. The equivalent focal length of our Nikon camera is 1.5 times the lens parameter. That is to say, as I said before, the 35mm focal length is suitable for shooting humanities. In fact, for our camera, the focal length we want to adjust is 23 mm.

The shooting focal length mentioned before refers to the equivalent focal length ~, which means that for our Nikon camera, the equivalent focal length should be divided by 1.5.

Here is an exercise for Feng to answer:

So, what is the equivalent focal length of the 1 inch sensor lens in the above picture?