About app

Use professional photo-finish technology on your smartphone. Use the slit camera technique to measure the finish time of any racing event with high accuracy. Get a picture to determine the winner with high precision.

Photo-finish allows you to:

  • Measure finish time with 0.005 – 0.05s precision (depending on camera FPS)
  • Determine the winner of the race.
  • Save a picture to prove the winner and result.
  • Share this picture with your friends.

Android version

Photo finish stopwatch
Photo finish stopwatch
Developer: Sport app studio
Price: Free

Mac, iPhone, iPad version

‎Photo finish app
‎Photo finish app
Price: Free+

How it works

  1. App made a series of slit photos of the finish line.
  2. Each photo frame has a timestamp with precise time.
  3. When on the frame you see that the finish line is crossed it means that the timestamp of a specific frame defines the finish time.



  1. Point a camera at the finish line. The solid line should point at the finish. The dashed line shows the frame border.
  2. Select the proper direction.
  3. Select proper frame width.
  4. Start the stopwatch at the race start.
  5. When the winner approaches the finish line, start recording.
  6. When the athlete crossed the finish line – stop recording.
  7. Find the frame when the winner crosses the finish line. The timestamp at the cursor line shows the precise result.


The application uses the slit-photo technique. It combines a series of frames to the resulting image in chronological order. The scale at the top of the resulting image shows an approximate timeline. Numbers at the bottom of every frame show timestamp milliseconds.

Depending on how the winner approaches the finish line it is more comfortable to combine frames in “left to right” or “right to left order”.

Frame width.

This setting depends on the distance between you and the finish line and the winner’s speed. If you are too close or the winner is too fast, then it can cross the frame sector too fast to get a clear image. Thus it is better to increase image width. From another point, the size of the resulting image is limited. If the frame is too wide then you will have less time to record the winner result.


The estimated stopwatch precision is about 0.05s. It depends mainly on the device camera frame rate. Standard phones support 30fps. 1/30 = 0.033ms. Also, if device performance is low, the app can skip some frames.


  1. Made some tests before using the app in the Olympic final to ensure that optimal point of view and settings are selected. 
  2. You can use volume buttons to start the stopwatch and recording.
  3. Use a tripod or other way to stabilize a camera to get smooth pictures. 
  4. To keep the device pointed directly to the finish line you can use a headset or Bluetooth remote control from a selfie monopod.
  5. Made records from different points to be sure that all athletes and the finish line will be visible.
  6. Ensure that your device is charged.
  7. If there is not enough contrast you can put some white screen on the backstage of the finish line.

Extra features

  1. Use the gallery to view result images history
  2. Swipe up and down on the sight zone for the camera to zoom in and out.
  3. Share result images with friends
  4. Use a pinch gesture or double-click to scale result image.
  5. Use the volume buttons, Bluetooth control, or headset to stat-stop recording then your device is locked on the tripod.
  6. Use the app setting to control maximum result width, scale color, sound, etc.
  7. Use your device as a starting gun. It will replay the shot sound and give a flash signal to start the race.


The Mac version is released

Enjoy our app on the desktop platform. Now it is available on the App Store for the MacOs starting Mojave (10.16) It allows using the USB webcam to get the photo-finish images. https://apps.apple.com/app/photo-finish-app/id1638534762

2.0 Version released

Introducing the new “stopwatch sync” feature. 1. Now you can “share” the stopwatch start time over devices.  2. Set the main stopwatch as a server. Server id will be generated. 3. Set other devices as a client and enter the server id. Now stopwatch time on all client devices will be synchronized with the server …


Please contact support@photo-finish.app with any problems or questions.