This article explains everything you need to know about the Raspberry Pi camera autofocus.
It applies to all Raspberry Pi Models, and all Raspberry Pi camera modules: V1.3, V2.1, HQ, and V3.
Luckily, you are in the right place. Arducam has the most extensive solution to autofocus on Pi cameras.
So let’s dive right in and clarify this issue once and for all.
Here is the definition of autofocus from Wikipedia:
An autofocus (or AF) optical system uses a sensor, a control system, and a motor to focus on an automatically or manually selected point or area.
Easily, we get all the answers we need. Here are the 3 prerequisites for autofocus:
To focus is to move the lens. To autofocus is to automatically move the lens.
The focus motor is the “what” to move the lens, and the control system is the “how” to move the lens. When we focus manually, our hands function like the focus motor, and our brain functions like the control system.
Therefore, autofocus does not mean no focusing process is involved. It’s just that the focus motor and the control system take over the job for your hand and your brain.
Well, do the Raspberry Pi cameras meet these prerequisites?
For now, only the Camera Module 3 series has autofocus.
Let’s go over the prerequisites list again and see how the official Raspberry Pi cameras match.
The first 3 official Raspberry Pi cameras are not designed with autofocus in mind, instead, they just meet the basic needs.
The idea of the basic needs goes like this: You can get a clear picture with manual focus. The focus motors and control system not only add to the complexity but also add to the cost. Not everyone needs that. No need to meet all autofocus prerequisites.
Does this mean the official Pi cameras can’t do autofocus?
Yes. The first 3 official Raspberry Pi camera modules (V1/V2/HQ) cannot do autofocus themselves, period.
Does this mean there is no hope for Pi cameras to do autofocus?
Absolutely not. Arducam has fixed the issue and made it possible.
The logic to fix the issues is simple:
For those Pi cameras that don’t have a focus motor and a control system, then we build variants that do.
Let’s break down the two unmet prerequisites one by one.
First, it’s the focus motor.
Let’s consider the focus motor a part of the lens assembly.
In case you don’t know, there are two kinds of lens assembly in Raspberry Pi cameras:
This leads us to two methods to design a Pi camera that support autofocus:
Second, it’s the control system. The Raspberry Pi should be able to control the focus motor.
Let’s consider how the Raspberry Pi is connected to the focus motor before we set up the connection:
From above, we know that the key physical connection is the MIPI CSI camera ribbon cable. If so, do we have anything on the MIPI CSI connection that can help us control the motor?
I2C bus. More specifically, the I2C for the VideoCore processor.
i2c_vc
Set to “on” to enable the i2c interface, usually reserved for the VideoCore processor (default “off”).
I2C in raspberry pi camera pinout, useful for controlling the focus motorSo, we use the i2c_vc to control the motor. What we need to do is to add the following line to the /boot/config.txt.
dtparam=i2c_vc=onNow that we’ve met the prerequisites, what else is needed?
The last thing to do is to automate the focus process with a program.
Let’s first get the motors moving.
With a simple python program, we can use the keyboard keys to move the focus motor.
If you are interested in how we’ve done that, here is the python code for software motorized focus control.
import os
import time
import sys
import threading
import pygame,sys
from pygame.locals import *
from time import ctime, sleep
pygame.init()
screen=pygame.display.set_mode((320,240),0,32)
pygame.key.set_repeat(100)
def runFocus(func):
temp_val = 512
while True:
for event in pygame.event.get():
if event.type ==KEYDOWN:
print temp_val
if event.key == K_UP:
print 'UP'
if temp_val < 1000:
temp_val += 10
else:
temp_val = temp_val
value = (temp_val<<4) & 0x3ff0
dat1 = (value>>8)&0x3f
dat2 = value & 0xf0
os.system("i2cset -y 0 0x0c %d %d" % (dat1,dat2))
elif event.key==K_DOWN:
print 'DOWN'
if temp_val <12 :
temp_val = temp_val
else:
temp_val -= 10
value = (temp_val<<4) & 0x3ff0
dat1 = (value>>8)&0x3f
dat2 = value & 0xf0
os.system("i2cset -y 0 0x0c %d %d" % (dat1,dat2))
def runCamera():
cmd = "sudo raspistill -t 0"
os.system(cmd)
if __name__ == "__main__":
t1 = threading.Thread(target=runFocus,args=("t1",))
t1.setDaemon(True)
t1.start()
runCamera()Now we get a camera module with a software-controlled focus motor. That’s already a big step forward. You won’t have to focus near the camera module with your bare hands. Instead, you can sit remotely and adjust the focus with software.
Adjust the focus of a Pi camera with keyboard arrow keysHowever, if we want to enable autofocus, we need the Raspberry Pi to decide whether the camera is in focus, and it should stop moving the focus motors. But how would the Pi know?
As the biggest open-source computer vision library, OpenCV can help us make the Pi smart enough to tell whether the camera is in focus – by contrast detection.
sudo apt-get install python-opencvThe intensity difference between adjacent pixels of the sensor naturally increases with correct image focus. Then the Pi can adjust the motor until the maximal contrast is detected.
Arducam provides an OpenCV-powered autofocus example in Python. Here is what the image looks like on Raspbian when it runs.
Raspberry Pi camera autofocus in RaspbianIf you are interested in how we’ve done that, here is the python code for autofocus.
import cv2 #sudo apt-get install python-opencv
import numpy as py
import os
import time
import smbus
bus = smbus.SMBus(0)
try:
import picamera
from picamera.array import PiRGBArray
except:
sys.exit(0)
def focusing(val):
value = (val << 4) & 0x3ff0
data1 = (value >> 8) & 0x3f
data2 = value & 0xf0
# time.sleep(0.5)
print("focus value: {}".format(val))
# bus.write_byte_data(0x0c,data1,data2)
os.system("i2cset -y 0 0x0c %d %d" % (data1,data2))
def sobel(img):
img_gray = cv2.cvtColor(img,cv2.COLOR_RGB2GRAY)
img_sobel = cv2.Sobel(img_gray,cv2.CV_16U,1,1)
return cv2.mean(img_sobel)[0]
def laplacian(img):
img_gray = cv2.cvtColor(img,cv2.COLOR_RGB2GRAY)
img_sobel = cv2.Laplacian(img_gray,cv2.CV_16U)
return cv2.mean(img_sobel)[0]
def calculation(camera):
rawCapture = PiRGBArray(camera)
camera.capture(rawCapture,format="bgr", use_video_port=True)
image = rawCapture.array
rawCapture.truncate(0)
return laplacian(image)
if __name__ == "__main__":
#open camera
camera = picamera.PiCamera()
#camera.awb_gains=4
#camera.exposure_mode='off'
#camera.awb_mode='fluorescent'
#open camera preview
camera.start_preview()
#set camera resolution to 640x480(Small resolution for faster speeds.)
camera.resolution = (640, 480)
time.sleep(0.1)
print("Start focusing")
max_index = 10
max_value = 0.0
last_value = 0.0
dec_count = 0
focal_distance = 10
while True:
#Adjust focus
focusing(focal_distance)
#Take image and calculate image clarity
val = calculation(camera)
#Find the maximum image clarity
if val > max_value:
max_index = focal_distance
max_value = val
#If the image clarity starts to decrease
if val < last_value:
dec_count += 1
else:
dec_count = 0
#Image clarity is reduced by six consecutive frames
if dec_count > 6:
break
last_value = val
#Increase the focal distance
focal_distance += 15
if focal_distance > 1000:
break
#Adjust focus to the best
focusing(max_index)
time.sleep(1)
#set camera resolution to 2592x1944
camera.resolution = (1920,1080)
#save image to file.
camera.capture("test.jpg")
print("max index = %d,max value = %lf" % (max_index,max_value))
#while True:
# time.sleep(1)
camera.stop_preview()
camera.close()Now that we’ve understood the camera I2C can be used as a control signal to move the lens, we can take it even further.
If to focus is to move the lens, then to zoom is to move the elements inside the lens.
We want to control not only the lens but also the elements inside the lens: we can have an autofocus zoom lens. Together with pan and tilt servos, we build a PTZ camera for the Raspberry Pi with autofocus possibilities.
The Pivariety Project brings Pi’s hardware ISP tuning and camera control algorithms to more camera modules.
With better support (AE, AWB, and AF), our autofocus cameras can not only focus faster but also can produce higher quality images/videos than those native camera modules.
That’s everything about how we’ve made autofocus possible on Raspberry Pi cameras. However, here are some of our suggestions:
That being said, here are V1,V2 and HQ Arducam camera modules that support autofocus features.
The 5MP V1 and 12MP HQ cameras are a full camera module, and that means you can directly plug its camera ribbon cable into the Raspberry Pi’s CSI slot. The 8MP V2 version is a drop-in CCM replacement, and you need to detach the one on your V2 camera PCB and then attach this one to it.
It has an AUTO FOCUS!! Works perfect. Tested successfully on Raspberry Pi zeroW and the 3B+ using Raspian and MotionPi OS. The clarity is amazing because it’s got a micro motor for auto focus that’s total silent. The response time is fast.
Overall the camera waa great and perfect for my simpler, python based project. The camera is easy to set up. Simply plug the camera cable into the raspberry pi. The camera interfaces quickly and easily with the picamera library and picture has great resolution even under lower light conditions. The auto focus works well as advertised.
I like this camera so much better than the official Raspberry Pi V2 camera!
The white balance adjusts automatically (in contrast to the official V2, which has pinkish tint in many environments). There is focus control, but it requires some software (simple code that works over I2C). This is more convenient than mechanical control of the V2, which is not always possible to do if the camera is in a case.
And finally, it makes much more sense for the price.
Something I have found important in object recognition is clarity of the object in the picture. Auto-focus really helps that. I highly recommend this camera if you are learning how to program for A.I..
Simple installation and worked without any tweaks.
Sharpest focus I’ve seen out of my Raspi cameras to date
I setup a bird camera using my raspberry pi and the standard camera was OK, but because it had the fixed focus most of the birds were out of focus. I bought this auto focus camera and with a little programming I was able to improve my pictures. Not all birds are fully in focus (they move too quick) but overall they are much better.
There was a little bit of work to setup the hardware and software, but nothing too challenging if you have done stuff with Raspberry Pis in the past.
Replacement for the 5mp camera that had died. Works a peach, very nice image, no night vision but dont require that and easy to install. Made my CR-10 S4 / Octopi very happy
Well, that brings us to the end of this overview.
To conclude: The official Raspberry Pi camera modules do not support autofocus, but Arducam has made it possible to achieve autofocus by controlling a focus motor in our customized module via I2C.
Why do you need the camera module to do autofocus on Raspberry Pi?
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