Theoretically, the picture quality of a half frame with 20 million pixels is the same as that of Quan Huafu with 40 million pixels, right?

This is all on sale. According to this calculation, the pixel will return to zero and the sensor will not exist.

Hello, generally speaking, the two can basically be equated. But, in fact, there are many differences. Let me analyze it in detail:

Nikon D500, exactly 20 million pixels, is very expensive. But rich people still buy it, and they don't dislike aps!

First, Quan Huafu's lens is actually different from APS's.

The basic optical principle tells us that the larger the negative, the worse the resolution of the photographic lens.

The resolution of photographic lens of large format film camera is very poor.

The photographic lens of a small negative camera has a high resolution.

This is a conclusion of measuring the resolution of photographic lens alone.

Therefore, the resolution of the photographic lens specially designed and manufactured for APS frame is higher than that of Quan Huafu.

Therefore, the resolution of Quan Huafu's photographic lens is higher than that of medium-sized photographic lens.

Second, take Fuji APS micro-sheet as an example.

Fuji often promotes its own APS system, which is well optimized and can basically be tied with full-frame cameras.

Among them, a large part of the reason is that Fuji's photographic lens is specially developed and optimized for APS frames.

Of course, Fuji's aps camera lens is not cheap, and its cost performance is low.

This is also because Fuji used good materials in pursuit of optimization.

Third, take Panasonic GH5S as an example.

Although Panasonic is a M43 system, the high sense of Panasonic GH5S is also quite good. Although it is still not as good as Sony A7 series Quan Huafu micro-single, can it really get away with it?

This case is to illustrate the problem of high sense.

That is to say, for example, Canon 7D2 or Nikon D500, as sports photography or bird photography, there is no problem. Rich people will also buy Canon 7D2 or Nikon D500, and they won't dislike that this is only an APS half frame.

If the rich completely despise Canon 7D2 or Nikon D500, then this shows that there is really a big problem.

But obviously, rich people, as well as news photography, sports photography and bird photography, still many people buy Canon 7D2 or Nikon D500!

In a word, we can't blindly trust Quan Huafu.

The APS framework has its reasons for existence.

It's different.

Suppose Quan Huafu sensor A originally had 36 million pixels, and an APS-C cut from the same wafer corresponds to 654.38+06 million pixels, that is to say, when you watch the photos taken on the 2 million pixel display, the photos taken in Quan Huafu state are reduced from 36 million pixels to 2 million pixels, and the signal-to-noise ratio gain of 465,438+06 files is obtained; The photos taken in APS-C state were reduced from 6.5438+0.6 million pixels to 2 million pixels, and three grades of signal-to-noise ratio gains were obtained. The SNR difference between them is 654.38+0.654.38+06, and the whole picture will be purer. If APS-C wants to get the same image quality as the full frame, it must use a slower shutter or a larger aperture. If the shutter can't be changed, then assuming the aperture of the whole frame is F 1.8, APS-C must use F 1.2 to compensate the image quality difference of 1. 16-accordingly, ISO must be lowered to obtain correct exposure.

In fact, this topic has little to do with pixels per inch. Take Quan Huafu and M43, which are easy to calculate and understand, as an example:

Assuming that the design of sensitivity gain is completely consistent, the shutter speed is fixed, and the output brightness is the same when shooting with ISO 100+F2, but the Quan Huafu signal-to-noise ratio is two steps higher. At this time, the output brightness of Quan Huafu is the same, but it is two steps lower. At this time, the output brightness of Quan Huafu is adjusted again, with the same signal-to-noise ratio and brightness.

This problem is very complicated. The simplest answer is to shoot flowers and birds, and you will encounter a cutting problem. The quality of the image cut out by 40 million pixels and 20 million pixels is absolutely different, so you should consider what camera you use to do, and don't blindly follow.

Why do so many people answer that they don't know the half-full relationship?

Half width is the common name of APS-C, and its sensor diagonal is11.5 to 1.7 of the standard 135 film. Different manufacturers and models of photoreceptors have different areas. Before Canon,11.3 was called APS.

As far as the common Sony half-width photoreceptor is concerned, its area is generally11.5 *11.51/2.25, that is to say, 20 million half-width corresponds to 45 million full-width and/kloc-.

As far as Canon's half-width photoreceptor is concerned, its area is generally11.6 *11.61/2.56, which means that 20 million half-width corresponds to 50 million half-width,/kloc-.

As far as the photoreceptors of the same technical level and the same manufacturer in the same period are concerned, as long as the pixels per inch are the same (20 million to 45 million or 50 million), half-width photoreceptors are equivalent to cutting a piece in the center of the full-width photoreceptors with corresponding density, so there is no difference in image quality. The only difference lies in the imaging range and the blurring effect of the whole picture when using the same lens. Because although the whole picture is cut by half, the contrast of blurring ability is the same as that of the composition from the same perspective. Under the same composition, the whole picture needs to be closer to the subject, which leads to a shallower depth of field and a stronger background blur.

The picture quality of half frame and Quan Huafu is not only the same in theory, but also the same in practice. The difference between them is that the frame size of direct imaging is different, and the frame of Quan Huafu is larger than half a frame. Let's look at the difference between the direct imaging frame and the actual data:

Quan Huafu: Canon 5D4:

30.4 million pixels with a maximum resolution of 6720*4480.

Direct imaging frame size: 237.07* 158.04(CM)

Nikon D850:

45.75 million pixels, with a maximum resolution of 8356*5504.

Direct imaging frame size: 291.25 *194438+07 (cm)

Half frame: Fuji X-T4

2665438+ million pixels, and the maximum resolution is 6240*4 160.

Direct imaging frame size: 220. 13* 146.76(CM)

The frame size of direct imaging refers to the size of the photo directly made without any cropping after the photo is taken. From the above data, we can see that Canon 5D4 can directly take photos with a long side of 2.37 meters, while Nikon D850 can directly take photos with a long side close to 3 meters. Even the half-frame Fuji X-T4 has a direct imaging size of 2.20m on the long side, which is only a dozen centimeters smaller than the 5D4 in Quan Huafu.

What is the image size we usually need? The 28th National Photographic Art Exhibition will be held this year, which is the most authoritative and influential exhibition in China. The submission platform requires that the pixels of the work should not exceed 5M and the long side should not be less than 3,000 pixels.

General online photography platforms, including China photography and mass photography, only require that the long side of a picture should not exceed 1024 pixels.

The photos used in our life, even the wedding photography in the studio, are rarely more than 2 meters high. The photos we usually use for exhibitions are generally below 24 inches, and the long side of a standard 24-inch photo is 60CM.

Whether it is large-scale exhibitions, online submissions or photos used in daily life, the number of pixels of existing digital cameras, whether it is Quan Huafu or half-frame, has far exceeded the actual requirements.

There are great differences between digital photography and film photography. Film needs to be enlarged to become a photo. On the contrary, digital photography is not zooming in, but zooming out. Once digital photography is taken, it is a big photo, which needs to be reduced before it can be used for submission, exhibition or life. When both the Quan Huafu and the half-frame are reduced to the same size, their pixel numbers are the same, and their image quality is equivalent.

At present, half-frame cameras have more than 20 million pixels. Due to the high development of camera technology, all digital cameras on the market, whether Quan Huafu or half-frame, can meet the needs of high-quality photo shooting and most photos. Therefore, when we buy a camera, there is no need to blindly pursue Quan Huafu. In this regard, we should review the barrel theory. In digital cameras, the shortest wooden stick is the most useful. It is no longer necessary for us to care about the pixels of a digital camera, but to determine whether the camera meets our own needs by looking at the direct imaging size of the camera.

The number of pixels per unit area is decisive. The same is 40 million pixels, but in different square centimeters, the resolution is very different, and the picture quality is certainly different!

On the other hand, it is easy to understand that the picture quality of 40 million pixels in a half frame is almost the same as that of 20 million pixels in Quan Huafu!

Theoretically, the picture quality of a half frame with 20 million pixels is the same as that of Quan Huafu with 40 million pixels, right?

Answer: No, the reasons are as follows:

(1) Image quality not only has parameters such as latitude, but also resolution is very important. In the case of similar lens performance, the resolution of 20 million pixels in a half frame is definitely far from that of 40 million pixels in Quan Huafu. I have already tested it.

(2) If the 20 million pixels in a half frame are the same size as the 40 million pixels in Quan Huafu, then a half-full photo will be at a disadvantage.

(3) The imaging quality of the camera depends not only on the size of the photosensitive element, but also on the factory year, brand, brand and positioning of the photosensitive element. The performance of photosensitive elements varies greatly with camera brands. The performance of the latest photosensitive element is much better than that of the product ten years ago, so it cannot be concluded that the image quality of 20 million pixels in a half frame is theoretically the same as that of 40 million pixels in Quan Huafu.

It's different! The so-called Quan Huafu fields are all relative to 135 standard film, and the size of 135 standard film is 36 x 24 mm. At the early stage of the development of digital SLR cameras, due to technical reasons, it is impossible to produce photosensitive elements with the same size as 135 film. Therefore, the manufacturer adopts the size smaller than the film size 135 as the size of the photosensitive element of the digital SLR camera, that is, the size of APS-C (and the size of APS-H is similar to it). The frame of this size is much smaller than that of 135, so people call it a semi-frame.

On the same size photosensitive element (for example, 135 film size), the pixels are equal! There is no comparability in different sizes!