If there is no such functions in your phone, choose a camera instead. The setup of the camera is a little more complicated. The simple method is to use aperture first, set ISO to 100. According to the ambient light, the aperture receives around f6 ~ f18, the time for exposure is controlled within 30 seconds, or use Bulb model for exposure. It's best to have a Shutter Release. A wireless shutter is highly recommended. You can control the shutter time and prevent camera shaking at as well.
