Why do some smartphones not support slow motion?

When a normal video is recorded, 30 or 60 individual photos/frames are captured by a smartphone per second. Not just capturing, post processing and writing onto memory. But when a slow motion is captured, 120, 240, 480 or more, sometimes even 1920 frames are captured by a smartphone per second.

 That requires some insane processing power. Also the camera hardware should be high end, sometimes featuring a high speed cache built into the camera sensor itself.

Sony Xperia smartphones have the best slow motion in the industry since 2017.

They did 720p at 960fps in 2017, 1 year before other smartphones could do, eg: Samsung S9 in 2018.

Xperia XZ2, released in 2018 did 1080p at 960fps, and Sony Xperia 1 II, released in 2020, did 4K HDR at 120fps. All that happened because Sony develops camera sensors for themselves and their own smartphones. 

All their flagships since 2017 had a fast cache storage built into the sensor itself.

How can I shoot videos in slow motion using my smartphone?

The basics of stop motion are pretty straight forward on your phone.

1. download a stop-motion app. There are free ones.
2. get a tripod or some kind of stand where you can lock your phone. You don’t want to do this hand-held, you need the camera to be steady.
3. Start a project with the app. Put the object in place. Press the (usually) red button. It will take a photo of the object.
4. Move the object just a tiny bit.
5. Press the button again.
6. Repeat the process for as many frames you want.

The stop-motion animation will let you see a “ghost” of the last frame so you have a reference of where the object was. The position shift of the object between one frame and the next should be very small.