Overview
Let’s look at two examples. When taking photos of flowers, insects, etc., the background is shot blurred to highlight the subject. But when taking photos of souvenirs, landscapes, etc., the background is shot as clearly as the subject. These two are different depth of field. The former is a narrow depth of field, shooting focus on the subject, only a small distance, the view before and after the subject are defocused, clear range is small. And the latter is a large depth of field, clear range is larger.
Definition of depth of field: The range of distance between the front and rear of the subject measured by the camera lens or other imager front to obtain a clear image of the image. Commonly speaking, that is, the object being photographed at the focus point plane of the scene, in the film will form a clear image, in front of the focus plane somewhere to its rear somewhere there is a range, the scene within which can form a clear image, this range is called depth of field, the discussion of depth of field, we generally use “Narrow” to describe, that is, shallow depth of field (depth of field) or large depth of field (depth of field). That is, shallow depth of field (narrow depth of field) or large depth of field (large depth of field).
DOF Application for Trail Camera
Usually, the focal length of the lens of a trail camera is fixed, so in the process of lens selection, the focal length and depth of field parameters are particularly important, the following chart shows the relationship between focal length and depth of field. A good lens, usuallty, for a good lens , its depth of field and focal length to achieve the best balance.
The floowing table show DOV parameters of the Lens F35( Greatview trail cameras GV-TC200 and GV-TC600 use this lens)
| Focus distance(m) | Depth of Field ( F35) | Computational Basics: | Pixel Size | |
| Rear subject(m) | Front Subject(m) | |||
| INF | — | — | efl | 7.51 |
| 8 | INF | 3.958 | F/# | 2.4 |
| 7 | INF | 3.697 | Fuzzy Circle（C) | 0.003 |
| 6.5 | INF | 3.552 | H | 7.833 |
| 6 | 25.64 | 3.398 | Pan-focus 3.917 m ~ ∞ | |
| 5.5 | 18.466 | 3.231 | ||
| 5 | 13.825 | 3.052 | ||
| 4.5 | 10.576 | 2.858 | ||
| 4 | 8.174 | 2.648 | ||
| 3.5 | 6.327 | 2.419 | ||
| 3 | 4.862 | 2.169 | ||
| 2.5 | 3.672 | 1.895 | ||
| 2 | 2.686 | 1.593 | ||
| 1.5 | 1.855 | 1.259 | ||
| 1 | 1.146 | 0.887 | ||
| 0.5 | 0.534 | 0.470 |
By analyzing the parameters of the lens, we believe that the trail camera will achieve the best balance of depth of field when the focus distance is 3M. The total DOV can reach 7.031m （2.169+4.862）
If it is more than 3 meters, although you can get farther Rear suject distance, but that blurred distance in front of the camera will be farther. As you know, as a trail camera, it often needs to catch animals that very close to the camera, and if the focal length is too far, it means that the animals close to the camera will be captured in a blurry photo.
Conclusion
Users tend to pay too much attention to the FOV when choosing a camera and ignore the DOF, but as we discussed above, DOF is actually a very important parameter, especially for trail cameras, a good camera lens if used for an excellent DOF, then it will bring you a clearer imaging experience.