With autofocus

Raspberry Pi camera module 3 introduced

16. Januar 2023, 10:00 Uhr | Tobias Schlichtmeier
Kameramodul 3 Raspberry Pi
The camera module 3 for the Raspberry Pi is now available.
© Raspberry Pi

After 2016, Raspberry Pi launches a new camera module. The new Sony sensor in camera module 3 offers a higher resolution and more pixels. Instead of the fixed optics of the previous models, the new module offers an autofocus option.

Raspberry Pi also collaborates with Sony for the new camera module. This time with the back-illuminated »IMX708« sensor: It offers a higher resolution (twelve megapixels), a larger and more sensitive pixel design, and supports high dynamic range images.

The camera module was Raspberry Pi's first official accessory. It came onto the market in 2013. The infrared-sensitive »NoIR« variant followed in the same year. Camera Module 2, based on Sony's eight-megapixel »IMX219« sensor, was launched in 2016 – with 2 million units sold. However, CMOS image sensor technology is constantly evolving. Developers will be pleased to know that despite the new technology, the Foundation is able to maintain the price of $25 for the standard version, with the wide variants with the more complex optical stack being offered for $35.

Higher resolution, wider pixels

Compared to the IMX219 with 3280 x 2464 (8.1 megapixels) and 1.12 μm pixels, the IMX708 offers 4608 x 2592 (11.9 megapixels) resolution with 1.40 μm pixels. The higher horizontal resolution allows finer details to be captured – the 16:9 aspect ratio enables HD video to be recorded using the entire sensor area. In addition, the larger pixels and more advanced pixel architecture result in higher sensitivity and better low-light performance.

Options for the detection field

The standard variants of camera module 3 offer a (horizontal) field of view of 66°, which is close to the 62° of the predecessor module. In these variants, the higher linear resolution of the IMX708 directly results in a higher angular resolution and a more detailed image.

The Wide variants of the camera modules offer a horizontal image section of 102°. They distribute the higher linear resolution of the IMX708 over a larger angle, resulting in a slightly lower angular resolution than the camera module 2, but enabling interesting new applications such as digital panning.

Autofocus

All previous camera modules had fixed focus optics. For the first time, camera module 3 supports autofocus. For this, the lens assembly is mounted on a swinging coil drive that allows it to be moved back and forth relative to the sensor until a selected area – the center by default – of the scene is optimally focused.

To select the appropriate lens position, Raspberry Pi uses the phase detection autofocus (PDAF) capabilities of the IMX708 sensor and falls back to its own contrast detection autofocus (CDAF) algorithm if a reliable PDAF result is not available.

Compatibility

The camera module 3 is compatible with all Raspberry Pi computers with CSI connectors, i.e. with all models except the Raspberry Pi 400 and the Zero version introduced in 2016. The dimensions of the board and the positions of the mounting holes are identical to those of the camera module 2. Due to changes in the size and position of the sensor module, it is not mechanically compatible with the camera cover for the Raspberry Pi Zero case.

Furthermore, the new module is supported by the »libcamera« software as well as by »Picamera2-Beta« under Raspberry Pi OS Bullseye. However, not by the old closed-source camera stack. Developers must therefore make sure they have the latest version of the software, as only the current version offers the autofocus features.

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