A DSLR camera for video
The Canon 5Dmk2 was a game changer for independent video makers. It delivered a stunning footage quality at a fraction of the cost of a professional camera. The shallow depth of field of a full frame DSLR camera is a strong asset, but keeping your subject in focus is a challenge. Even now, 8 years later my Canon 6D still cannot keep a subject in focus during movie recording. You need to focus manually, which is very very hard with a shallow depth of field.
Since I bought my Canon 5Dmk2 8 years ago, I did several attempt to design a focus follower that could keep the subject in focus. They were all based on ultrasound distance sensors, but these sensors were not sufficiently reliable.
With 3D sensing technology evolving in a fast pace (lidar becoming affordable due to the developments in autonomous vehicles, TOF (time of flight) sensors, Intel Realsense, ...) I felt it was time to give it a new try.
I had a first generation Kinect available which proofed to be an extraordinary piece of hardware in earlier project. It creates a very accurate depth image of the scene, with a depth up to 6 meters. Sufficient for my proof of concept.
Since I bought my Canon 5Dmk2 8 years ago, I did several attempt to design a focus follower that could keep the subject in focus. They were all based on ultrasound distance sensors, but these sensors were not sufficiently reliable.
With 3D sensing technology evolving in a fast pace (lidar becoming affordable due to the developments in autonomous vehicles, TOF (time of flight) sensors, Intel Realsense, ...) I felt it was time to give it a new try.
I had a first generation Kinect available which proofed to be an extraordinary piece of hardware in earlier project. It creates a very accurate depth image of the scene, with a depth up to 6 meters. Sufficient for my proof of concept.
A Kinect based focus puller
A Raspberry Pi 3 is can easily read the camera and the depth map of a Kinect. By selecting a region of interest on the touchscreen, the Pi looks for the nearest distance in the region of interest and drives the focus ring of the camera with a stepper motor.
Here is a video demonstrating the proof of concept. Notice the region of interest that is selected (on the metallic statue or on the wooden statue) and how the focus is kept accordingly.