Slow motion can add interest and drama to footage in certain circumstances, especially when the scene contains moving elements at a relatively close distance
The Mini 4 Pro and Air have improved slow motion capabilities compared to previous DJI models. They have a Slow Motion mode at 100 fps at 4k and 200 fps at 1080 p resolution for extreme results. Other possibilities are available using different frame rates and slowing down the footage on a video editor
I will show how to apply different degrees of slow motion to footage taken with the DJI Mini 4 Pro and Air 3 using different frame rates. The settings for slow motion are the same for the two models
You can check the prices for the different configurations of the Mini 4 Pro and the Air 3 (commission earned)
Other related articles you may find interesting:
- Mini 4 Pro and Air 3, Camera settings for video
- Mini 4 Pro video quality
- Air 3 video quality
- Air 3 telephoto lens
If you prefer to watch this as a video, you will find my YouTube version at the end of this article
Why slow motion?
Slow motion is not particularly useful when shooting landscape footage at high altitudes and far from the target, which is often the case with drones
But any time moving elements are in the scene, we can add more interest by slowing down the action. With the camera close to the action, slow motion conveys a different mood
Let’s see a few examples of slow motion applied to footage taken with drones and ground-based cameras
This technique adds a lot of interest not only to sports and action but also to groups of people walking or dancing, cars, sports, waves, fountains, and waterfalls
Another spectacular effect is obtained by speed ramping: suddenly slowing down from regular speed to slow motion or the other way around
Super Slow motion
In the Mini 4 Pro and Air 3 we access the Photo/Video mode by clicking on the icon above the big red shutter. If we select Video, a second menu appears on the left with options for Normal, Night, and Slow-motion. Let’s select the last one
As we can see from the Resolution and Frame Rate window on the lower right, In Slow Motion mode, the frame rate at 4k resolution is 100 fps, which is very slow and can be considered super slow motion
This is a major improvement for the Mini 4 Pro and Air 3, as the Mini 3 Pro has a maximum frame rate of 60fps at 4k
The most widely used frame rates are 24 or 30 fps. I will refer to 24 fps, as this is the one I use in my video projects
Footage shot at 100fps is four times slower than normal, very slow
When filming at a resolution of 1080p, there is an option for 200 fps for an extreme eight times slow motion
In slow-motion mode, the footage is slowed down automatically. There is no need to convert the 100 fps to the frame rate of the timeline. This mode is ideal for users applying slow motion for the first time, as it is very user-friendly, immediately ready to use
Accelerating vs slowing down
It is always possible to accelerate footage while editing without loss of quality. The same is not true when slowing it down
Accelerating
Suppose we have 4 seconds of footage shot at 24 frames per second, which equals 96 frames (24 multiplied by 4)
If we want to accelerate the footage to double speed we need 2 seconds of footage still at 24 frames per second, so 48 frames
| Length in seconds | Frame rate | Number of frames |
| 4 | 24 fps | 96 |
| 2 | 24 fps | 48 |
We have plenty of frames available, all the software has to do is drop half of the frames and keep the 48 needed, so there will be no loss of quality
Slowing Down
But if we want to slow down our 4-second clip to half speed, 192 frames are needed (24 frames per second multiplied by 8 seconds)
| Length in seconds | Frame rate | Number of frames |
| 4 | 24 fps | 96 |
| 8 | 24 fps | 192 |
There are only 96 available so the editing program has to create new frames and this is where the quality declines, whatever method we use
Frame Rates
Footage taken in slow-motion mode is very slow, which is excellent for certain situations, however, we may prefer a more subtle effect on other occasions
With both models, in 4 K resolution, we have several frame rates available to apply slow motion:
- 30 fps
- 48 fps
- 60fps
The best way to slow down a clip is to start with more frames. In a 4-second clip shot at 48 frames per second, 192 frames are available
If we slow it down by half, we end up with an 8-second clip. Since our project is at 24 fps we need 24 frames x 8 seconds, which equals 192. We have exactly the frames we need
The best results are obtained using a frame rate that is a multiple of the one used in the timeline so that all the frames are used
Using a frame rate of 48 fps the resulting footage will be at half speed, compared to quarter speed in the previous example using the Slow motion mode
Other frame rates can be used for slow motion, for example, it is possible to shoot at 30 fps and encode at 24, to get a very subtle 20% slow-down effect used quite often in movies
However, the software has to create one frame out of each five. This can cause small artifacts, but the result is good enough for most usages
We can also use 60 fps for a 60% slow-down effect, slightly slower than half speed. In this case, some frames will again be extrapolated
Slow-motion editing
Footage taken in 30, 48, or 60 fps plays at normal speed before editing. We need to interpret it or slow it down in a video editor to get slow motion
I am using Premiere Pro, which offers two different methods. I will show you the simplest one, which is available in most other video editors
After selecting the clip on the timeline, we right-click and choose speed duration. We are presented with this window to enter the desired speed in percentage
In this case, we have a 48 fps clip and we want to slow it down to half speed, so we enter 50%, the duration of the speed displayed just below will double.
If the footage was shot at 30 fps we must enter 80%, to get a subtle reduction of 20% compared to normal speed. For a file shot at 60 fps, enter 40% for a result slightly slower than half speed
Someone may ask: since the 60 fps footage can be used at normal speed, what about always shooting at 60 fps just in case we decide to slow it down later?
I suggest planning and shooting at higher frame rates only footage that we want to slow down. 60 fps footage produces bigger files, requires more processing resources and it is not as cinematic when played at normal speed on a 24 fps project