Use your mobile phone to familiarize yourself with the focal length
After buying the camera, novice Xiaobai often finds it difficult to choose a lens that suits his use scene when faced with a large and unfamiliar lens group. Fortunately, nowadays everyone has a mobile phone that can play SLRs, which can help you familiarize yourself with the feeling of each focal length and let you find your most commonly used and favorite focal length.
First introduce "Equivalent focal length"The concept: The term "equivalent focal length" is due to the different frame sizes, that is, the different sizes of the bottoms. With the same lens, photos taken with a full-frame body are much wider than those taken with a half-frame body. It is now accepted that full-frame lenses are used as the benchmark, and half-frame lenses must be converted to full-frame focal lengths by multiplying by a conversion factor. The half-frame lenses of Sony, Nikon, and Fuji are directly multiplied by 1.5, and the half-frame lenses of Canon are multiplied by 1.6.
Half-frame equivalent full-frame focal length = lens focal length × conversion factor
Take Sony as an example. Sony's half-frame body with Sigma San Muskete lenses 16 mm, 30 mm, and 56 mm is equivalent to the full-frame focal length, multiplied by 1.5, and the equivalent is 24 mm, 45 mm, and 84 mm respectively.
Now we change the half-frame camera to a mobile phone, which also satisfies the above conversion formula, only need Change the conversion factor to "25"That's it. How did this "25" come from? Here is a professional website: EXIF Viewer
First, use the different focal lengths of the mobile phone to take a random photo. After uploading it, the website will automatically feed back the EXIF information of this photo, including what focal length is required to take this photo in full frame. I took a picture with the main camera, and it shows that the viewing range is equivalent to a full-frame 25mm lens:
My current mobile phone is redmi K30S, below I will use it as an example to put the test results of the corresponding focal length:
| The focal length of the mobile phone camera interface | Equivalent full-frame focal length |
|---|---|
| 0.6 | 15 |
| 1 (main photo) | 25 |
| 2 | 51 |
| 3 | 78 |
| 4 | 103 |
| 5 | 127 |
| 6 | 155 |
| 7 | 179 |
| 10 | 255 |
The bottom of the mobile phone is similar, the conversion factor can basically be used directly 25, if you want to be more precise, just use the above website to try one by one.