Þingvellir National Park is one of the best spots to capture the Northern Light. Wearing sufficient clothes are important because sometimes it takes up to 2-3 hours for waiting the Aurora. Since you are standing in a certain position all the time, it's better to wear more than double as usual. For taking photography, it is vital to wear thick gloves and boots because you can't stop taking photos of Aurora. I forgot wearing gloves and my hands were freezing and turned red.
Weather preview
Aurora forecast for Iceland is used to predict the possibilities of seeing Northern Light in Iceland at real-time. It is often see Northern Light like a small green light but you need luck if you want to see Aurora "rain" like the pictures in Internet.
During my stay, it has been raining for 4 days and it is cloudy all the time. Although the forecast is 6.6/9 for our day in Þingvellir. We expected that Aurora won't be as obvious as the one in Google picture due to the cloudy weather. Sometimes the camera can identify the light more than human eyes haha. (in fact it is!)
Photography
For taking photos, 1/20 or bulb are gonna used so it's better to take with tripod. for slow shutter speed. Otherwise, your photos will look blurry since one photo might take up to 20 seconds to take.
/without tripod
It's not the prettiest and best view but now I can tell - I saw Northern light -