Triggertrap is an excellent app, allowing you to trigger you camera with your smartphone and make use of more than 12 different triggering modes.
This app usually retails for $9.99/£5.99 but it is currently available for only $4.99/£2.99. Click here to download.
You can trigger using:
• Time Lapse
• Eased Timelapse (timelapses with acceleration!)
• Distance-lapse (take a photo every 30 ft/m)
• Vibration and shock sensors
• Sound detection (Clap to take a photo!)
• Facial Recognition sensor
• Motion detection
• Magnetic & metallic detectors
• Long-Exposure HDR**
• Long-Exposure HDR Timelapse
• Bulb ramping
• Star Trail mode
• Cable Release (press to take a photo) which also supports Long-exposure shots (exposures of up to 24 hours!)
Of course, all the modes are fully configurable, to enable you to get trigger happy with your camera – in any way you like. We have even built in a Sunrise Mode (it uses the information from your GPS location to tell you exactly when the sun will set and rise where you are), and a Lag-O-Meter to measure your camera lag, for even more accurate HDR photography.