Saturday, 18 October 2014

High speed video, slow motion

Already from the start, Nikon 1 cameras have been able to record video at a 1200 frames per second rate, which is very fast. A normal video frame rate is 30 FPS, in NTSC countries, so you are able to record videos 40 times as fast.

This can be used to make interesting slow motion videos. In this example, I used a Nikon 1 J1 to record the mechanical shutter of the Lumix GM1 camera.

The newest Nikon 1 V3 camera also has the high speed video feature. It can record 1200 FPS, without audio, and in an unusual 416x144 pixel resolution. When the video recording is started, it lasts only for 3 seconds, so the timing of the start of the video is crucial.

The camera then gives you a 2 minute clip with a 30 FPS slow motion stream, as the three seconds are expanded into two full minutes of video footage. The files are MOV format, and are generally around 13MB in size.

Rather than using the whole imaging sensor for recording the high speed video, which would have been useful, only a small part of the centre of the sensor is used. A 2080x720 pixel rectangle in the centre is used for 1200 FPS video, which corresponds to an extra crop factor of 2.9x. Here is an illustration of the sensor area used:

I used this feature to record the lighting of matches. The match was fixed to a vice, for stability. In the background, I put a white board.

I used the camera, with the 70-300mm f/4.5-5.6 (my review) tele lens. When mounting this combination to a tripod, it is good to have the optional tripod mount for the lens. Since I wanted to capture the match in portrait mode, I tilted the camera 90 degrees on the Benro B2 ball head:

I set the lens to 250mm, and used the exposure parameters: ISO 1000, 1/1250s, f/5.6. Autofocus works in the high speed video mode also, in the sense that the camera will focus before starting the video. In this case, I set the focus distance close to the minimum possible with the lens.

To start the video recording, I could have simply pushed the video button. However, that would have set off vibrations in the camera/lens, which would have made the first seconds of the video useless. And since you can only record three seconds in high speed mode, this is very bad news.

The solution is to start the video recording by using the Nikon ML-L3 IR remote control. That way, you can start the recording while keeping the camera stable.

Here, I have put two videos in one single frame, and you can see the results from the experiment:


The high speed video function of the Nikon 1 cameras is a bit of a gimmick. It is hard to use, with the three second limit, and the very limited resolution. However, it can be used to create fun clips, with a bit of planning.

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