{"id":8479,"date":"2022-02-01T09:08:31","date_gmt":"2022-02-01T14:08:31","guid":{"rendered":"https:\/\/dronebotworkshop.com\/?p=8479"},"modified":"2023-04-12T06:21:28","modified_gmt":"2023-04-12T10:21:28","slug":"pi-autofocus","status":"publish","type":"post","link":"https:\/\/dronebotworkshop.com\/pi-autofocus\/","title":{"rendered":"Raspberry Pi Autofocus Camera & libcamera"},"content":{"rendered":"\n

\"Download \"Parts<\/a> \"View<\/a> \"Download<\/a><\/p>\n

Today we will be checking out a new camera for the Raspberry Pi, the Arducam Autofocus camera.\u00a0 We\u2019ll also be looking at libcamera, the new camera stack provided with the latest Raspberry Pi operating system.<\/span><\/p>\n

Introduction<\/span><\/h2>\n

One of the many wonderful features of the Raspberry Pi is that it comes with a CSI camera port, allowing you to add video capabilities to your projects. \u00a0 All modern Raspberry Pi boards have this feature, from the inexpensive model Zero to the top-of-the-line 8GB Raspberry Pi Model 4.<\/span><\/p>\n

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The cameras used with the Raspberry Pi have evolved over the years. We now have a wealth of cameras to choose from, from the 5MP Version 1 to the 16MP Raspberry Pi HQ Camera.\u00a0 And the models are not just limited to ones made by Raspberry Pi, other manufacturers such as Waveshare and Arducam also have produced Raspberry Pi cameras, some of them outperforming the originals, with sensors capable of up to 21MP resolution.<\/span><\/p>\n

Today we are examining one of these cameras, a new camera from Arducam that has some impressive specifications, especially considering its low price.<\/span><\/p>\n

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And we\u2019ll also be working with a new camera stack packaged with the latest version of the Raspberry Pi operating system, libcamera.<\/span><\/p>\n

Arducam Autofocus Camera<\/span><\/h2>\n

The Arducam Autofocus Camera<\/a> (currently it doesn\u2019t seem to have a model number) is a brand-new offering that has just come off of its successful Kickstarter campaign.\u00a0\u00a0<\/span><\/p>\n

This camera is one of Arducam\u2019s \u201cPivariety\u201d series of devices, and it\u2019s not the only one of the series with autofocus capabilities.\u00a0 However, it does stand out from the rest of the offerings due to (a) its low price (same as the Raspberry Pi Version 2 Camera), (b) its 16MP sensor, and (c) its form-factor, which is identical to that of the version 1 and 2 cameras.<\/span><\/p>\n

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The camera is also packaged with a small plastic case that provides fairly effective weatherproofing, and that has a \u00bc-inch thread to allow the camera to be mounted on a standard photographic tripod.<\/span><\/p>\n

libcamera<\/span><\/h2>\n

If you are familiar with using cameras with the Raspberry Pi, then you have likely run across two command-line utilities – <\/span>raspivid<\/span><\/i> and <\/span>raspistill<\/span><\/i>.\u00a0 These two applications allow you to take video and still pictures and adjust a wealth of camera parameters like image size and brightness.<\/span><\/p>\n

With the release of the latest version (as of this writing, of course) of the Raspberry Pi operating system, code-named \u201cBullseye\u201d, <\/span>raspivid<\/span><\/i> and <\/span>raspistill<\/span><\/i> have been replaced by a new camera stack named <\/a><\/span>libcamera<\/span><\/i>.<\/span><\/p>\n

libcamera<\/a> (the lower-case spelling is intentional) is an open-source camera stack for controlling embedded camera hardware, and it is available for Linux, Android, and ChromeOS. To adapt libcamera to an operating system requires the OS developer to write a custom pipeline handler, which Raspberry Pi has done.<\/span><\/p>\n

libcamera supports all the existing Raspberry Pi cameras, as well as a number of devices from 3rd-party manufacturers. Developers can add additional camera modules as well. It can be used at the command line, as well as within Python programs.<\/span><\/p>\n

To make it easier to switch existing applications to libcamera Raspberry Pi has provided a set of <\/span>libcamera-apps<\/span><\/i>.\u00a0 The chart below describes their functions:<\/span><\/p>\n

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Of particular interest are <\/span>libcamera-still<\/span><\/i> and <\/span>libcamera-vid<\/span><\/i>, which effectively replace the functions performed by <\/span>raspistill<\/span><\/i> and <\/span>raspivid<\/span><\/i> respectively.<\/span><\/p>\n

We will be using these libcamera-apps today to check out our new autofocus camera.<\/span><\/p>\n

How Autofocus Cameras Work<\/span><\/h2>\n

Before we get started with our new camera, I thought it might be useful to see how cameras perform automatic focusing.<\/span><\/p>\n

In order to focus a camera, you need to be able to move the position of the camera lens relative to the image sensor.\u00a0 You can see this effect with a magnifying glass or another simple lens, move it toward and away from your eye and observe how the target image changes focus.<\/span><\/p>\n

In a manual focus camera, you can accomplish this by twisting a focus ring, which in turn changes the lens position.<\/span><\/p>\n

Focus Motor<\/span><\/h3>\n

In an electronic focus design, you replace the manual ring with a motorized one. On some cameras, this is done with an actual small motor, whereas others use a mechanism that works more like a solenoid. In both cases, we\u2019ll refer to this as a <\/span>focus motor<\/span><\/i>.<\/span><\/p>\n

To autofocus a camera, you need to have some sort of control system that moves the motor.\u00a0 The three components are illustrated here:<\/span><\/p>\n

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By adding a motor to the camera lens assembly, we can use software to control the focus. We could write a program to do this manually, or we could use a program to automatically achieve this.<\/span><\/p>\n

On the Raspberry Pi we have to figure out one detail before we can work on a software-based focus system – how do we electrically attach to the focus motor to control it?<\/span><\/p>\n

There are two possibilities:<\/span><\/p>\n