Skills of time-lapse photography

Time-lapse photography is widely used in scientific research and professional scientific documentary creation. It reveals the mystery of nature by concentrating time, and has strong visual expression. The time-lapse photography function of smart phone is simple and easy, even teachers and students who have no creative experience can quickly master it, improve the creative level of scientific images, and feel the unique pleasure of time-lapse photography.

What is time-lapse photography?

Time-lapse photography is a kind of photography technology that compresses the process of several hours, days or even longer into a shorter time. Through the concentration time, it shows the change process that we can't recognize with the naked eye and reveals the mystery of nature. Time-lapse photography is rich in subjects, such as plant growth, element crystallization, organic matter decomposition, star transfer, cell division and so on.

Time-lapse photography is a shooting method that reduces the frame rate in the early stage and plays the picture at the regular frame rate in the later stage. For example, if you shoot 1 frame per second in the early stage and play it at a speed of 25 frames per second in the later stage, the playing time will be 25 times shorter than the real shooting time, so that the original unobvious change process will be quickly presented.

The mobile phone comes with the time-lapse photography function of the photography APP.

Smartphones generally have time-lapse photography. Take the iPhone as an example, open the camera APP, slide the screen to time-lapse photography mode, stabilize the phone, lock the focus and lock the exposure according to the methods introduced in previous issues, and then start time-lapse photography. However, the time-delay shooting function of the mobile phone is generally that the shooting time interval and shooting duration are automatically calculated by the mobile phone, which cannot be set manually, and it is difficult to predict the shooting effect when the shooting time is long.

Mobile phone third-party time-lapse photography APP

Mobile phone third-party time-lapse photography APP can be freely set by the creator according to the different speed of the subject, which has more creative space. At present, there are many kinds of smartphone time-lapse photography apps in Android and iOS systems, and different apps are similar in function and usage. This paper takes Timelapse Pro as an example to introduce its usage.

(1) Set the shooting interval and shooting duration.

According to the changing speed of the subject, the shooting time interval needs to be adjusted accordingly before shooting. Click "Settings" in the lower right corner to open the interface as shown in figure 1. There is no essential difference between "beginner" and "expert" in setting. "Videofps" indicates the frame rate, generally 25 frames/second is selected (which is more suitable for domestic website broadcasting specifications). "Shooting interval" is the shooting interval (default unit is seconds), which is used to set the interval for the mobile phone to automatically shoot 1 picture. For fast moving objects, the shooting interval is short, while for slow moving objects, the shooting interval is long.

There are many experiences about setting time intervals on the Internet, such as shooting fast-moving clouds, interval 1 second, slow-moving clouds, interval 10 second, plants growing for 2 minutes, the shadow of the sun, interval 1 0.020 second and so on. These experiences can be used for reference by novices, but they are not immutable. Photographers need to have enough knowledge of the subject, and constantly explore and adjust in practice.

For beginners, the most common mistake is that the shooting interval is too long, which leads to the jumping and incoherence of the shooting effect. Therefore, in the case of abundant storage capacity of mobile phones, it is best to set the shooting interval shorter, so as to obtain enough material and leave room for post-production. "Shooting time" refers to the total duration of actual shooting (the default unit is seconds). "Start recording delay" is to delay the shooting of 1 frame for a few seconds to avoid vibration caused by touching the mobile phone.

(2) Start shooting

Press the "Start" button, and the interface will prompt the existing shooting settings, as shown in figure 1. Where "Timelapselength" refers to the film length obtained according to the existing settings. If all the settings meet the shooting requirements, you can press "Start New Delay" and the phone will jump to the shooting interface. Among the three icons in the upper left corner of the interface, (here is a thumbnail, please copy it from the PDF) means "shooting time", (thumbnail) means "shooting frame number" and (thumbnail) means "shooting time", and the values will change at any time according to the shooting situation. The icon on the right (thumbnail) is used to lock the focus and (thumbnail) is used to lock the exposure. After the setting is completed, you can click the icon (thumbnail) and the phone will automatically start shooting at the set time interval.

(3) End shooting

When the scheduled shooting time ends, or when the shooting is finished by manually clicking the icon (thumbnail), the mobile phone will automatically jump to the video generation interface and automatically render the shot picture into a dynamic video. In this interface, you can preview the video, give it a name, describe it, add soundtrack and filter effects, and then click "Save" to save the video. Click the icon (thumbnail) and click "Export to camera film" to export the video to the mobile phone video library (Figure 2).

Matters needing attention in time-lapse photography

Whether the mobile phone is fixed or not is the key to success or failure of shooting. Since the smartphone's time-lapse shooting APP will automatically synthesize video, it is difficult for us to make up for the mistakes in the previous shooting through post-processing. The jitter or out-of-focus during shooting may lead to long-term shooting. Therefore, we suggest that beginners use a tripod to fix their mobile phones and practice from a fixed lens. After mastering the operation skillfully, they can realize more vivid and interesting time-lapse photography effect with the help of auxiliary equipment such as rotating pan/tilt and electric slide rail.

In addition, special attention should be paid to exposure control. When shooting in natural light, if the exposure is locked, the light change may lead to overexposure or underexposure of the picture, so we suggest that beginners use automatic exposure mode (this operation has some disadvantages, that is, when the light changes greatly, the generated video will flicker); If we can accurately predict the weather when shooting and judge the light receiving trend of the subject, we can lock an intermediate exposure value and control the brightness of the subject better. If possible, you can choose to shoot indoors and use artificial light to improve the success rate of shooting.

In addition, when shooting, make sure the phone has enough power and memory, turn off the alarm clock and switch to flight mode.

Difficulties in mobile phone time-lapse photography

Compared with digital cameras, time-lapse photography with mobile phones is simple and easy, which omits a lot of post-processing and synthesis processes. Its creation difficulty mainly lies in grasping the changing law of subjects in the early stage. The creator of time-lapse photography must be familiar with the subject and make reasonable predictions about the moving direction, range, speed and environmental changes of the subject in order to successfully complete the shooting.