Help need with python script for PiCamera

Question

I am working with the Raspberry Pi camera and need some help regarding the python script. I need to capture a set of 5 images continuously every 5 minutes interval until I want it to stop. This set of images will be captured with increment in the shutter speed.

Right now, I only have the script written for capturing 5 images.

from picamera import PiCamera
from time import sleep
camera=PiCamera()
camera.resolution=(1024, 768)
camera.start_preview(fullscreen=False, window=(100,200,500,600))
camera.capture_sequence(['image%02d.jpg' % i for i in range (5)]) 

Please let me know how to set of images continuously with range of shutter speed. Thanks in advance.

Answer 1

If I've understood correctly, you want to capture 5 images, each with a different shutter speed, wait five minutes, and then repeat. In that case, capture_sequence isn't applicable as it would capture all frames with the same shutter speed.

In that case, the code you want should look something like this:

from picamera import PiCamera
from time import sleep
camera=PiCamera()
camera.resolution=(1024, 768)
camera.start_preview(fullscreen=False, window=(100,200,500,600))
at = 1 # keep track of the current image
while True:
 for shutterspeed in range(250,1500,250): # use shutterspeeds of 250, 500, 750, 1000, and 1250 microseconds, set this to the range of values you're interested in
 camera.shutter_speed = shutterspeed # set the shutter speed to this many microseconds
 sleep(2) # documentation suggests a short 2 second delay for the sensor to adjust
 camera.capture('image%05d.jpg' % at) # save the image in the current folder with 5 leading zeros in the filename
 at = at + 1 # increment the image number
 sleep(5*60) # wait 5 minutes
camera.stop_preview()

• Bemche: Hey, Thank you for your response. I have tried this script and it captures only one image after every 5 minutes. But I would like to capture 5 sets of images, each with different shutter speed, wait for minutes and then repeat to capture another 5 set of images. Thanks.
• Fred: You should get 5 images every 5 minutes. ls -ltr for me clearly shows image00001.jpg to image00005.jpg taken at 11:19 and image00006.jpg to image00010.jpg taken at 11:24. The images may not look very different though due to the shutterspeeds being so similar. Try changing for shutterspeed in range(250,1500,250) to for shutterspeed in range(500,4500,500) for a wider range of shutter speeds, which should give more different images.

Answer 2

I'm trying also to do some HDR images to acquire at the end a whole 8 or super8 film. Every picture of the film will be acquired with different stops. Here the code that I have already tested and that works fine:

from picamera import PiCamera
from time import sleep
from fractions import Fraction
camera = PiCamera()
camera.rotation = 180
camera.resolution = (3280,2464)
camera.framerate= 1/1
sleep(1)
camera.capture('img_0.jpg')
exposure = camera.exposure_speed
camera.exposure_mode = 'off'
i=1
while i < 4:
 camera.shutter_speed = exposure * 2**i
 sleep(1)
 camera.capture('img_plus_'+str(i)+'.jpg')
 camera.shutter_speed = int (exposure / 2**i)
 sleep(1)
 camera.capture('img_minus'+str(i)+'.jpg')
 i+=1

First I take an image at EV0 and I save the exposure_speed so that I know the EV0 value. After that, I change the shutter_speed so that I have under- and over-exposed pictures

Regards

Gian Carlo

Answer 3

The task could be run every five minutes using cron.

Save your script as (e.g) /home/pi/mycapture.py

crontab -e

Then add

*/5 * * * * python /home/pi/mycapture.py

You would need a date/time stamp in the filename to avoid overwriting.