I posted a couple of long exposures with my GoPro a while back. In that post, I quoted the article that gave me the idea in the first place. It didn’t cross my mind that I could easily find out what the shutter speeds actually were.
Photogene ⁴ is one of my go-to apps for post-processing on iOS. Not only does it have advanced features such as noise reduction and healing, it has the ability to view a photo’s Exif data. Since I usually transfer photos taken with the GoPro directly to my iPhone, the app came in handy (screenshot below).
This confirms that the ISO and aperture are fixed at 400 and f/2.8, respectively. The shutter speed is most likely affected by the amount of light. But there’s another variable that I didn’t keep track of and control, and that’s the interval of time between shots. I’ve included three photos below with varying shutter speeds. The first two were done with a timelapse interval of 0.5 sec and the last with a 10 sec interval.