How to make SLR photos stand out in the circle of friends?

Dear friends, the Spring Festival is coming. The traditional Spring Festival is a family gathering. But now, young people seem to like to travel during the Spring Festival. After all, there are only two long holidays a year. Even chubby parents are planning to go out to road trip, so the photo contest of friends circle in the Spring Festival every year must be the most topical. The old joke is well said: I ran into a friend in the breakfast shop downstairs but didn't dare to say hello, because in the circle of friends, I was in America. Although it is only a paragraph, it fully shows that high-quality photo printing is enough to attract most people's attention. Then the question is coming, what is the highest realm of friends circle? Probably what the girls said: "Wow, was it shot by a SLR? ! "But how do you make your travel photos jump out of the box of the mobile APP filter, so that people who don't understand can see it at a glance? Xiao Pang will give you a suggestion today.

In other words, how to give full play to the advantages of the camera on the mobile phone, from shallow to deep, the first is the focal length. The biggest advantage of a camera is that it has everything from fisheye to cannon. For travel photos, the tension of the ultra-wide lens is completely beyond the reach of the panoramic mode of the mobile phone. In addition, the details of the telephoto end are beyond the reach of mobile phones. Therefore, if you want to reflect the advantages of SLR in the circle of friends in the simplest and rudest way, then make more fuss at both ends.

If you think this is too simple and rude, maybe you don't have an ultra-wide telephoto lens at all? Your depth of field is still very shallow The most intuitive performance of SLR's advantage of no inverted frame is depth of field. You said that your 18-55mm telephoto end is F5.6, which seems to have no advantage in depth of field. But in fact, even this basic camera lens can achieve a shallow depth of field less than 1 cm at the nearest focusing distance of 25 cm at the end of 55 mm. Taking some flowers and plants can fully demonstrate the inherent advantages of large CMOS SLR. If it is APS-C frame plus 50mm F 1.8, 1.5 m or so, the depth of field is only 2 cm, which avoids the clutter of the background. If you are interested, here is the formula for calculating the depth of field:

There are four factors that affect the depth of field: the object distance u (the distance from the object to the lens), the focal length f, the aperture value n and the maximum dispersion circle diameter c, and the value of c is defined as the quotient of CMOS diagonal divided by 1500 (so c is related to the frame). Here, 1500 is an experimental value, and some manufacturers use other values, such as 1730 used by Zeiss. The greater the value, the stricter it is. Under this definition, the diameter of Quan Huafu's dispersion circle is c = 0.0289 mm, and Nikon DX is taken as an example for APS-C frame, and the diameter of dispersion circle is c = 0.0201mm. 4/3 frame c = 0. 144 mm, and total depth of field = foreground depth of field-background depth of field, so there are:

Of course, there are also tools directly available on the Internet to calculate the depth of field. In addition, the camera lens is not a single lens, and the calculation of object distance and image distance is actually very complicated, so the depth of field formula can only be regarded as an approximation, so don't care too much about accuracy. But Xiao Pang is still the same sentence: Don't underestimate your camera lens. It's still no problem to shoot a depth of field that can catch people's eyes in a circle of friends. Moreover, compared with the blur effect of dual-camera mobile phones, the authenticity of SLR is much stronger (the picture below is 18-55mm@55mm F5.6).

If you don't want to PK from the perspective, and you don't want to challenge your own aesthetics with mindless blur, for travel scenery films, SLR or Quan Huafu /APS-C format has an obvious advantage, that is, sharpness, which can be said to be positively related to the format. The larger the frame, the higher the definition. Next, let's talk about theory:

Lens imaging is to transfer information from the object plane to the image plane, which belongs to analog signal. Due to the limitation of lens resolution, this analog signal has the highest frequency. The function of CMOS is analog-to-digital conversion through sampling. In order to recover analog signals without distortion, the sampling frequency should not be less than twice the highest frequency in the spectrum of analog signals. We know that point light sources will be converted into Airy spots on CMOS. There are countless point light sources in the photos we took, corresponding to countless Airy spots, and each pixel is reflected on CMOS. Combined with the sampling law mentioned above, one MTF line pair corresponds to two pixels (Airy spot). The width of CMOS line pair with MTF=0.5 = the diameter of dispersion circle, that is, 1 pixel = Airy spot radius =1.22f. The lens with aperture F=2.8 emits yellow-green light with wavelength =555nm. By introducing Airy spot calculation formula, the pixel width is about1.9m.. Therefore, each CMOS size has its own upper limit of pixels per inch. If pixels are added without increasing the CMOS area, these extra pixel sampling information will be directly lost as high-frequency data, so large-size CMOS is inherently more conducive to high definition. You can enlarge the photos taken by a 20-megapixel mobile phone by 100%, and it is easy to find that the pixels are basically blurred without details, while the SLR will not have this problem.

How to ensure the high resolution of the whole picture when shooting landscape photos, in other words, to make the whole picture "in focus" and enlarge it to 100%, or to release the photos after later cutting and recombination, which requires learning the so-called "hyperfocal distance" game. The so-called hyperfocal distance is to push the depth of field behind to infinity (as shown above, the grass in the foreground and the mountains in the farthest background have clear images). There is a formula:

When the 24mm lens is shot in F2.8, the formula can be brought in to explain that when the focus position is 10.234 m, the back depth of field will reach infinity. If the focus position is closer to it, the depth of field at the back will be out of focus and begin to blur, but the focus position is farther away. Because the foreground depth of hyperfocal distance is still limited, that is, the focal length is /2, and in this case it is 5.117m. The whole of Quan Jingshen in hyperfocal distance started from this distance, and there is still a vague prospect within this distance. If you concentrate further, you will also push forward the starting point with deep prospects, which will not pay off.

Moreover, it can be seen that the larger the aperture value (that is, the smaller the aperture), the closer the focus can be, the deeper the foreground and the closer to the plane. For example, if this 24mm lens is shot with F8, focusing to about 2.5m can be in the depth of field range from 1.25m to infinity ... At the same time, the longer the lens focal length/the larger the frame, the farther the focusing distance and the foreground depth distance will be. Even if the aperture of Quan Huafu 85mm lens is reduced to F 16, it should be focused to 15m, so as to realize the hyperfocal distance from 7.5m ..

Therefore, if you want to make the whole photo clear, you can roughly calculate the focal length through a wide-angle small aperture to avoid the prospect of being too close and take a fully focused photo like the one below.

But be careful not to excessively narrow the aperture even in hyperfocal distance, because too small an aperture will cause diffraction problems and affect the image quality. In addition, try to shoot with low ISO and stand on a tripod. In addition, if you want to show your professional photography skills in a circle of friends, you should naturally use the RAW format, because most of them need to be released later, so you can send a few "working drawings" to warm up when you travel, which will naturally attract more people's attention. Of course, the disadvantage is that if it is really bad, there will be a gap between the output and the expected value, so it will suit you.

Finally, I hope everyone has a happy Spring Festival. Although there are still 1 months, I believe many people's hearts have already flown ~ ~