What are Star Trails?
Due to the Earth's rotation, the stars in the night sky appear to move in circular paths. A "star trail" photograph is a type of long-exposure image that captures this apparent motion, turning the stars from points of light into beautiful streaks or arcs across the sky.
This app automates the process by taking many photos over a period of time and merging them into a single, stunning star trail image.
Best Practices for Great Images
Phone Stability is Key
For the best results, your phone must remain perfectly still during the entire capture process. It is highly recommended to place your phone on a tripod or another stable, secure surface.
The app includes a built-in motion detector to prevent blurry images. If it detects movement during a capture, it will automatically stop the session to preserve the quality of the trail. In the pro version, you can adjust the sensitivity of this motion detection in the Settings menu.
Other Creative Uses
This app isn't just for stars! You can use the same technique to capture other types of light trails, such as:
- The flow of car headlights and taillights on a busy street at night.
- The light trails of airplanes landing or taking off from an airport.
- Any other long-exposure light painting scenarios you can imagine!
How to Use the App: Step-by-Step
Step 1: Before You Start
On the main screen, you will see a live preview from your camera. Point your phone at the sky or scene you wish to capture.
- Wait for the calibration to complete. This will attempt to set the brightness to the a reasonable brightness (or as adjusted with the settings in the Pro Version).
- If desired use the brightness slider at the top to adjust the brightness further. (Pro Version only)
- Press the "Start Capture" button to begin the process.
- The Help button (question mark icon) opens this guide.
- The Settings button (gear icon) allows you to adjust capture settings (this is a Pro version feature).
Step 2: During the Capture
Once a capture is in progress, the screen will display a live-updating preview of your merged image. You will also see key information about the capture:
- Images Merged: The number of photos that have been combined so far.
- Time Display:
- In the Free Version, this will always show the Remaining Time from the 10-minute limit.
- In the Pro Version, this depends on your "Completion Mode" setting:
- If set to
Manual Save and Close, it shows the total Elapsed Time.
- For all other automatic modes, it shows the Remaining Time for the current session.
- Gap Time: The amount of time not captured between merged images. The longer this time the larger gaps you may see with fast moving objects like airplanes.
To stop a capture:
- Press the "Stop Capture" button (in Manual mode) to end the session immediately and take you to the review screen.
- Press the "Stop All" button (in repeating Auto-Save modes) to stop the entire repeating sequence after the current session finishes.
- If the battery gets down to 3%, it will automatically stop and save the capture and close the application.
- If movement of the phone is detected, it will automatically stop the capture without merging the frame that experienced the movement. The sensitivity of this motion detection can be adjusted in the Settings menu within the Pro Version
Step 3: After the Capture
After a capture is manually stopped or completes (with the exception of auto-save modes), you are taken to a review screen showing the final image.
- Press the "OK" button to save the final, enhanced image to your phone's photo gallery in the "StarTrailCamera" album.
- Press the "Delete" button to discard the image without saving and return to the camera preview.
Reporting an issue with the app or to provide an enhancement request:
Free Version vs. Pro Version
Free Version
The free version has the following limitations:
- Capture duration is limited to 10 minutes.
- The Settings screen is disabled.
Pro Version Features
Unlimited Capture Duration & Brightness Control
Capture for as long as you like to create truly epic trails. You can also manually adjust the exposure brightness with a slider on the main screen.
Adjustable Settings
The settings screen allows you to fine-tune your capture for the best results. The settings are:
- Completion Mode: Choose what the app does after a capture session finishes.
- Manual Save and Close: After stopping, you will be shown a preview to save or discard. This is the default mode and shows elapsed time.
- Single Auto-Save and Close: The app automatically saves the final image and returns to the camera view when the "Capture Duration" is met.
- Auto-Save and Repeat (Manual Stop): The app saves the image when the "Capture Duration" is met, then immediately starts a new capture. This continues until you press the "Stop All" button.
- Auto-Save and Repeat (Set Captures): The app saves the image when the "Capture Duration" is met and starts a new capture. This is repeated for the number of times set in "Number of Captures".
- Number of Captures: This setting is only visible when the "Completion Mode" is set to
Auto-Save and Repeat (Set Captures). It defines how many times the capture session will be repeated.
- Capture Duration (minutes): This setting is visible for all "Completion Modes" except
Manual Save and Close. It sets the length of each automatic capture session.
- Minimum Target Brightness: Adjusts the baseline brightness for the auto-exposure calibration.
- Enable Final Image Enhance: Applies smoothing and contrast enhancement when saving the final image.
- Detection Sensitivity: Adjusts the sensitivity of the motion detection to prevent blurry trails if the camera is moved. If movement is detected, the capture will stop without saving the frame that experienced the movement.