PHOTO FINISH

- Try to stand higher than the runners and film down. This will minimize the risk that they obscure each other.
- Hold very still, or preferably, put the iPhone/iPad on a stand. This improves both image quality and accuracy.
- Adjust the slice width so the racer looks as normal as possible (arms and legs that move faster or slower than the body may still appear stretched out or compressed).
- If possible, try to get a smooth and even background.
- Good light conditions are essential to reduce motion blur and increase image quality. Check the exposure time in the preview. If it drops below 1/200 s, there might be some blurring.
- Newer devices record with a higher frame rate, e.g. 120 or 240 fps (see more below).
iPhone 6 and newer, iPhone SE, iPad Pro |
240 fps |
iPhone 5s, iPad Air 2, Mini 4, iPod 6 |
120 fps |
iPhone 5 & 5C, iPad Air & Mini, iPod 5 |
60 fps |
Older devices | 30 fps |
It is usually not possible to save a long finish as one image due to memory limitations in the iPhone/iPad. The problem can be reduced by scaling the image in the save dialog. You can also crop the image by rotating left and set crop marks. It is no problem to save the finish in several pieces by first setting crop marks around some competitors and save. Then set new crop marks and save again.
SprintTimer | High-end | |
Technique | Image slices | Image slices |
Frames/sec | 240 | >1000 |
Accuracy | 0.01s | 0.001s |
Accuracy (difference) | 0.001s | 0.001s |
Race time | Unlimited | Unlimited |
Recording time | 300 s | Unlimited |
Image height | 1280 - 1920 px | 500 - 2000 px |
Start | Manual/sound/Start gun/self start | Start gun |
Lens | Wide/Normal* | Tele (better) |
Cost | $3-$6 | > $5 000 |
However, recording video in landscape would reduce the resolution by almost 50% and have other disadvantages as well. The rest of the app is therefore in portrait view.
*Remember to turn off the rotation lock in the control panel or the settings app.
For accuracy reasons, you must, therefore, add time lines directly after the race, or if you don't have time to mark it, save the base video and add the time lines later. Do not save an image without time lines. A saved image cannot be processed and re-saved.
You can trust:
- The time display when scrolling a base video
- The time lines imprinted on an image created from a base video
- The time display when viewing a saved image (look at the imprinted lines instead)
Base videos are saved in the files app and can be deleted from there, or from the base video list. Photo finish images are saved in the Photos app and can be deleted there as well as from the list.
Dropped frames do not affect the timing. The recorded video contains timing information about each video frame, so when you scroll the base video, it will show the correct time. The same goes for the mark timelines; they are placed in the correct position. The worst that can happen with a lot of dropped frames is that essential parts of the body not being shown.
However, when you save a photo finish as an image, the timing information of the individual frames is lost. So when you play it back, SprintTimer will assume that each slice has the same time value, and the time display will not be correct (the imprinted timelines are still correct though). Do not save a photo finish image without timelines.
The drop rate can often be improved by restarting the device, setting it to flight mode, and turning off background updates.
VIDEO FINISH
There is no difference regarding information or accuracy when saving images or a processed video, so you can pick the one you find most convenient.
Saving the base video will give you full flexibility to recreate the photo finish at a later stage. Note that the "Previous race (back up)" is a base video.
Base videos are saved in the app and can be deleted from the base video list. Processed videos are saved in the Photos app and can be deleted there as well as from the list.
This will make it easier to identify the competitors, but might make it harder to see exactly when they pass the finish line.
However, if you do need very high accuracy in Video Finish you can use the "Dual mode" to interpolate between images and get the right 1/100 s.
So if you are experiencing missed competitors:
- Move closer, 2-4 m is a recommended distance for cross country runners.
- If you are unable to get close enough, go to the preview and zoom in to get the competitors to better fill out the frame.
- In the preview, you can also increase the detection sensitivity.
- Lower the frame rate, you seldom need 60 fps, unless you are dealing with very fast objects. If you want to increase the accuracy of the timing you can use the Dual mode when evaluating the race.
- In extreme conditions, consider turning off the motion detection.
START & START SENDER
- Sound via cable. Make a long microphone extension cable and place a microphone (e.g. an iPhone headset) close to the starter. This is the most stable and accurate method to start the clock. You can find tips on how to make a cable in the SprintTimer blog
- Sound via Walkie Talkie. Place one Walkie Talkie close to the starter and one close to the iPhone/iPad and let the sound trigger the start of the clock. This is a common set up that gives good accuracy and is usually the best solution for very long distances, e.g. in rowing and kayaking.
- With two devices and a WiFi network (existing or temporary router) you can use Start Sender. With a good network the accuracy is very close to a sound cable. Tips about setting up a temporary router in the SprintTimer blog
- Hand/Mic. You start the clock manually, but the sound is recorded at the same time and is used to correct the time. Ir requires some extra steps after the race, but gives much better accuracy than a manual start.
- Manual start. Easy to use, but gives the lowest accuracy.
5--4--3--2--1
The pauses will be even longer if you lower the voice speed (but the voice will sound more sluggish).
Note: Bluetooth will introduce a delay in the sound, usually around 0.1 s - 0.4 s. So there will be an error in the times recorded, This is discussed in this blog post.
After the synchronization, the latency will not affect sending a start signal, so an occasional red latency bar is of no consequence. The accuracy when using Start Sender on a low latency network is close to that of a direct sound input (see accuracy under Photo Finish above)
Some tips if the latency is high:
- Wait a few minutes to see if the sync latency drops.
- Disconnect and start the synchronization again.
- Try to connect to another network (i.e. 5 GHz instead of 2.4 GHz). Check that both devices are on the same network.
- Restart the router.
- Change the network channel if there are other networks in the area.
Cloud mode requires Internet access, but not WiFi.
In cloud mode the error might be a little larger since the devices must sync individually against a server and over a network with higher latency. But tests have shown that the error over a good 3G or 4G network is less than 0.02 s.
RESULTS MANAGER
The CSV-formatting can, therefore, be configured in the Setup before exporting.
GENERAL
- Restart your device. Turn it off with: Settings app> General> Shut Down. Or use the button combination for your device. Then press the sleep/wake button to restart.
- Remove the app and install it from the app store again. Note: This will remove saved base videos and results, so back up those first. Reinstalling the app doesn't cost anything
- Do a factory reset of your device. This should be done as a last resort since it might involve substantial work. Do a back up first!
*SprintTimer has been running hundreds of consecutive timing sessions over several hours on different devices without any problems.
- Restart the device, e.g. from the settings app. This clears out the memory and any app lurking in the background.
- Turn off 'Background App Refresh' under General in the settings app
- Set an iPhone to 'Flight mode' to avoid incoming phone calls at a critical moment. If you use Start sender you then have to turn on WiFi, and if needed, Bluetooth.
You have started the clock but not the recording:
If you put SprintTimer to sleep when you have started the
timer (but not the recording) it will automatically switch to
the backup clock. The accuracy of the total time will be
within a few hundredths of a second, and the difference between
the racers will still have a 0.01 s accuracy.
The recording has started:
You should NOT leave SprintTimer while you are recording a
finish. If you do the recording will stop.
Time the first race as usual. At the start of the second race, start a separate clock. When all participants in the first race have finished, process the finish and return to the start view. Look at the extra clock. Pick a time ahead of the displayed time and enter that as the "offset time" in the start setup. When the extra clock reaches that time, start the clock in SprintTimer.

- I am a single developer doing everything (from design to programming), so keeping all my apps up to date with new phones and iOS versions is challenge enough.
- It is more fun to develop new apps and improve the current ones, rather than repeating everything in another programming environment.
- One my app was converted to Android by some partners, but the sales was much lower than for the iOS version (it seems that Android users don’t buy apps).
SPRINTTIMER PRO
- Check that in-app purchases are allowed in the Settings app (in Screen time). If not, turn on and tap Restore.
- Check that you are logged into iCloud. If not, log in and tap Restore.
- Log out of the app store in the settings app. Then try to restore. You should then get a login dialog.
- Restart your device.
- Remove SprintTimer and install it from the app store again (remember to first export base videos and results that you want to keep).
- Access to SprintTimer for Mac.
- The Flying Sprint module.
- Human and QR-code detection in Video and Live Finish.
- Start Sender Public Cloud that let devices with different Apple ID:s communicate.
- Show the running time on an external display.
- Share Photo finish images with the on-line SprintTimer viewer.
- Detect competitors in Photo finish and give a preliminary winning time
- Support for a "staggered start" both at the start and in the start lists.
- Start lists and results are automatically synced between your devices.
- Multiple races can be exported as one CSV-file.
- Use a Bluetooth keyboard to start the clock and control the recording, and to mark the finish.
- Measure start reaction with Start Sender and Apple Watch.
- Copy and paste start lists from spreadsheets.
- Result list are grouped according to race day.
- Automatic transfer of the Base video to Start Sender in auto finish.
- Launch the Settings app.
- Tap iTunes & App Store.
- Tap on your Apple ID.
- Tap View Apple ID.
- Tap Subscriptions.
- Tap on SprintTimer Pro.
- Tap Cancel Subscription.
- Tap Confirm when prompted to confirm that you want to cancel your subscription.
SPRINTTIMER MAC
- AirDrop: Double click on the file and it will open SprintTimer.
- Import: Go to the base video list and tap the import button.
- Drag and drop: Drag the file to the main menu, the base video list or the app icon.
- Drag the scroll slider
- Press and hold the left or right arrow on the keyboard, to move faster press cmd+ arrow
- Click and drag anywhere on the image
- macOS 10.15 (Catalina).
- SprintTimer Pro on your iOS device
- The same iCloud account on both devices.
- SprintTimer 14.9 or later on iOS.
- No timing/recording
- No start on sound or motion in Start sender
- The start list stays open during marking
This page is also available at sprinttimer.app/support