SpeedClock vs Video tachometer

The iPhone speed radar - easy-to-use speed measurement in your pocket, anytime, anywhere! A unique, advanced app designed to easily measure the speed of cars, boats, skaters, skiers, cyclists, animals, models, footballs, tennis serves, etc. The system is based on motion detection, enabling you to track a moving object using a hand-held device alone. SpeedClock includes three separate speed measurement tools and two distance estimation tools. 

 Speed Radar 
 SpeedClock uses the camera to detect and analyze motion, and a reference distance to calculate the speed of an object. Define the distance to the object of interest, hold the iPhone still and let the object pass across the the screen. The speed is displayed automatically. SpeedClock is also able to automatically measure the speed and save an image of passing objects. The measurement can be initiated from an Apple Watch and the speed displayed on the watch face. 

High Speed Video Recording
 An additional speed tool records and processes a video, which enables SpeedClock to track small, fast object, such as flying balls, that can be difficult to catch with regular motion detection. 

It also calculates additional parameters like acceleration. Synchronized Timing Gates
 A third speed instrument uses two iPhone/iPads equipped with motion detection to start and stop the timer and measure the speed. The distance between the devices is used as reference, and the speed is calculated based on the time taken by the object to travel between the 'Start' and 'Stop' devices. The time is transmitted wirelessly over WiFi or Bluetooth. 

Distance Measurement 
The stadimeter uses the size of a known object, e.g. a car, to calculate the distance. 
The clinometer uses your own height as reference, along with the angle of the iPhone, to estimate the distance to a point on the ground. 
The distances obtained from either tool can then be used to calculate the speed. 
 See a demo video at the application website (www.appmaker.se/speedClock) ON LINE REVIEWS “All I can say is, Fantastic” http://www.madxperts.com/2010/12/03/measure-speed-app-speedclock-iphone-download/ "Wow, how cool is that!" http://www.ithinkdiff.com/turn-iphone-speed-measuring-gun-speedclock-download/ "You really going to like this app" dailyappshow.com/speedclock (video) "A useful utility for anyone needing to measure speed" appmodo.com/44581/ "Useful, easy to use and quite a bit of fun (4 of 5)" appvader.com/2011/03/review-speedclock-iphone/ "speedClock is a useful app when you need to check the speed of yourself, or an object for exercise, racing or simple curiosity (4.5 of 5)" www.cooliphoneipadapps.com/2010/12/speedclock.html "Astonishing" iphonelife.com/blog/5/speedclock-velocity-radar-099-app-lets-you-use-camera-measure-speed-objects "It is a pleasure to use and operate. A nice app for those looking for a open-ended radar gun app." http://appadvice.com/appguides/show/baseball-radar-gun-apps

When the frame rate of a video matches the speed of a particular part, the effect is the same as using a strobe light. In the video, that part freezes. Since the frame rate of a video can be adjusted, this effect can be used to determine the rotational speed of a part. The smartphone must support slow-motion video recording (filming at a high frame rate). This is the case for all smartphones starting with iPhone 5S. The range is as follows: • 0.5—240 Hz (30—14400 RPM), for all phones from iPhone 6 onward • 0.5—120 Hz (30—7200 RPM), for iPhone 5S THE HERTZ (Hz) VALUE IS MORE ACCURATE THAN THE REVOLUTIONS PER MINUTE (RPM) VALUE, SINCE REVOLUTIONS PER MINUTE ARE CALCULATED FROM HERTZ AND ROUNDING IS DONE. To get a clear image, good lighting is important. The clarity of the image is controlled by the exposure of the video (exposure time and light sensitivity (ISO)). If the exposure time is reduced, the image will increase in clarity, but brightness will lower. To increase the brightness, you need to raise the camera's light sensitivity (ISO), but then the amount of noise increases. You also need to manually adjust the focus of the camera. The app can record video. The video format depends on the selected format in the app settings. If your iPhone supports 4K video format (3840x2160), then you can record 4K video at the frame rate supported by your iPhone. Text with important information is added to the frames of the recorded video: the selected frame rate, exposure duration, ISO, time stamp, time difference between the current and previous frames (Tcurr. − Tprev.), the sequence number of the frame in the recorded video. If you want any other information to be added, then let me know. You can choose to add only part of this information, and you can choose a different text color. You also have the option of not adding any information. You can change the information that is added and the color of the text while recording a video. At high frame rates, frames that do not have time to be processed may be discarded. This does not affect subsequent frames and can be controlled using the time difference between the current frame and the previous frame (Tcurr. − Tprev.). Dropping frames affects the video frame rate displayed in the "Photos" app. But the time interval between frames that were taken one after another and were not discarded will correspond to the selected frame rate. Frames may be dropped even when shooting slow motion video using the "Camera" app. You can check this by looking at the frame rate for slow motion video in the "Photos" app. Video containing the app's interface can be captured using the iOS "Screen Recording" function. The app can take a photo with the measurement result, date, and time written on the photo. The exposure time and ISO settings will be saved in the photo's metadata. To take a photo that shows the app interface, tap the "Pause" button and take a screenshot. It is possible to choose a video format that has the best quality, but has a significantly lower maximum frame rate. The difference between the formats is clearly visible only when using the digital zoom. Also, when using a format with better quality, the Rolling Shutter effect is stronger. Therefore, the best quality format can be used at speeds less than about 2000 rpm. You can turn on hints for easier observation of changes in rotation speed. Hints show how to change the frame rate (decrease or increase) depending on the direction of rotation of the mark. The hints are selected manually, but then you do not need to remember this information. The hints are relevant for frequencies close to the rotation frequency. If the direction of rotation of the impeller is known, hints can be selected in advance. The arrow showing the direction of rotation of the impeller must correspond to the "+" button. The video tachometer measures the rotational speed in exactly the same way a stroboscopic tachometer would.