What's the difference between APS frame lens and 135mm Quan Huafu lens?

APS frame lens and 135mm Quan Huafu lens are different in focus distribution, depth of field, high sensitivity, wide angle and macro.

1, focus distribution: Quan Huafu's focus is relatively concentrated in the center, while APS-C machines are almost distributed in the whole picture. However, the reflector of APS-C frame itself is relatively small, and the secondary reflector can be close to the size of the reflector of APS-C frame. Therefore, APS-C frame has certain advantages over Quan Huafu in focus distribution.

2. Shallow depth of field: Under the same shooting conditions, Quan Huafu uses a longer focal length under the same aperture, and the depth of field is shallower than APS-C frame (for example, the coefficient of 1.5 or 1.6 is about one aperture shallower). But it is not necessary to use fixed focus for both. According to the formula of depth of field, if APS-C uses a first-order focal length but a larger aperture, the fixed focus is the same as Quan Huafu's depth of field.

3. High sensitivity: Therefore, high sensitivity has certain advantages over APS-C. To ensure that the subject falls within the depth of field under the same shooting conditions in low light environment, Quan Huafu needs a smaller aperture and higher sensitivity to achieve the effect of APS-C (or APS-C can safely use a larger aperture and lower sensitivity). Therefore, in terms of high sensitivity, there is no absolute advantage over APS-C.

4. Wide angle: Quan Huafu has fixed focus and fisheye, and the medium focus also has a lens of 24-70 F2.8, while the wide-angle equivalent viewing angle of the lens of APS-C medium focus F2.8 is 17-55, which is equivalent to a difference of 28mm.

5. Macro: This APS-C has advantages over Quan Huafu. It shoots the same size. APS-C uses a macro lens with short focal length and a macro lens with long focal length. In order to achieve a satisfactory depth of field, APS-C can use the best aperture, but it must use a smaller aperture for all lenses, which affects the imaging.

Extended data:

SLR lens selection skills:

First, do what you can.

Generally used to take family commemorative photos, it is enough to buy a portable fool machine. If it is a photography hobby, all kinds of special-purpose photos, then professional SLR cameras should be the focus of purchase. If you decide to buy a professional SLR, you will generally buy an affordable set first, and then gradually configure more lenses and professional accessories.

The second is to facilitate work.

Traveling lightly and being versatile is the working state pursued by photographers and the ideal goal pursued by the development of digital technology. From this, we can sum up two experiences of digital camera in equipment: first, the body is light and easy to carry, and second, the zoom of the lens must be at least 5 times, and it must be optical zoom.

Third, it is powerful and comprehensive.

The number and advantages and disadvantages of functions mean the range and advantages and disadvantages of the camera's ability to cope with and solve tasks in actual shooting. Although cameras can't do everything, functionally speaking, the more the better, the more powerful the better. The ideal function setting of digital camera is that it has powerful automatic shooting function and can control the working mode and setting of the camera independently and flexibly to obtain the best shooting effect. Of course, the price of this kind of camera is often higher.

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