StackerCam allows you to record long term exposures on your iPhone. To do this, the app takes multiple frames and stacks them up. This not only allows you to take long exposures but also enhances the signal to noise ratio in low light situations.
There are many opportunities to use long term exposures. For example, in a busy street during daytime, all the people and cars magically disappear in the averaged image.
To use StackerCam, hold your iPhone steady or place it on a tripod. Then adjust the scene and the resolution and press the RECORD button when you are ready. StackerCam will start to take frames and add them to the stack. The more frames, the better the picture quality will be. When you think you collected enough frames, press the STOP button. You can then adjust the image and save it to your photo library.