Time-lapse photography in Raspberry Pi - Step-by-Step Execution

Concept Flow - Time-lapse photography

Start Program

↓

Initialize Camera

↓

Set Interval Timer

↓

Capture Image

↓

Save Image

↓

Wait for Interval

↓

Check Stop Condition

No Yes↓

Repeat

The program starts, sets up the camera and timer, then repeatedly takes and saves photos at set intervals until stopped.

Execution Sample

Raspberry Pi

import time
from picamera import PiCamera

camera = PiCamera()
camera.start_preview()
time.sleep(2)
for i in range(3):
    camera.capture(f'image_{i}.jpg')
    time.sleep(5)
camera.stop_preview()

This code takes 3 photos with 5 seconds between each, using the Raspberry Pi camera.

Execution Table

Step	Action	Iteration (i)	Image Captured	Wait Time (seconds)	Output
1	Initialize camera and start preview	-	-	-	Camera preview started
2	Wait for camera to adjust	-	-	2	Ready to capture
3	Capture image	0	image_0.jpg	-	Saved image_0.jpg
4	Wait before next capture	0	-	5	Waiting 5 seconds
5	Capture image	1	image_1.jpg	-	Saved image_1.jpg
6	Wait before next capture	1	-	5	Waiting 5 seconds
7	Capture image	2	image_2.jpg	-	Saved image_2.jpg
8	Wait before next capture	2	-	5	Waiting 5 seconds
9	Stop camera preview	-	-	-	Camera preview stopped
10	End program	-	-	-	Program ends

💡 Completed 3 captures, loop ends, camera preview stopped, program ends

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
i	-	0	1	2	-
Image Filename	-	image_0.jpg	image_1.jpg	image_2.jpg	-
Camera Preview	Off	On	On	On	Off

Key Moments - 3 Insights

Why do we wait 2 seconds before capturing the first image?

The 2-second wait (see step 2 in execution_table) lets the camera adjust to lighting and focus before taking pictures.

Why is there a wait after each capture?

The wait after each capture (steps 4, 6, 8) sets the time interval between photos, controlling the speed of the time-lapse.

What happens if we remove the camera.stop_preview() line?

If camera.stop_preview() is missing (step 9), the camera preview stays on, which may waste resources or confuse the user.

Visual Quiz - 3 Questions

Look at the execution_table, what is the image filename captured at step 5?

A image_0.jpg

B image_1.jpg

C image_2.jpg

D No image captured

💡 Hint

Check the 'Image Captured' column at step 5 in the execution_table.

At which step does the program wait for 2 seconds before capturing images?

A Step 6

B Step 4

C Step 2

D Step 8

💡 Hint

Look at the 'Wait Time (seconds)' column for the 2-second wait in the execution_table.

If we increase the wait time from 5 to 10 seconds after each capture, what changes in the execution_table?

A The 'Wait Time (seconds)' values at steps 4, 6, 8 change to 10

B The 'Image Captured' filenames change

C The number of iterations increases

D The camera preview stops earlier

💡 Hint

Check the 'Wait Time (seconds)' column for steps after each capture in the execution_table.

Concept Snapshot

Time-lapse photography on Raspberry Pi:
- Initialize PiCamera and start preview
- Wait 2 seconds for camera adjustment
- Capture images in a loop with fixed intervals
- Save images with unique filenames
- Stop preview after capturing
- Control interval with time.sleep(seconds)

Full Transcript

This program uses the Raspberry Pi camera to take a series of photos at fixed time intervals. It starts by initializing the camera and showing a preview. Then it waits 2 seconds to let the camera adjust. Next, it captures images in a loop, saving each with a unique name and waiting 5 seconds between shots. After all images are taken, it stops the preview and ends the program. Variables like the loop counter and image filenames change step by step. Waiting before capturing and between shots controls the timing of the time-lapse sequence.