Towards the Core of Milky Way (Update)

by Wayne Wei on in Home

Smartphones usually have equivalent focal length of around 30mm. To take a close-up view of the core of Milky Way, cropping is needed to approximate similar focal length as 45-50mm lens with reduced resolution. Camera exposure setting needs to be changed. Previously I set 30 seconds exposure time to let the camera sensor receives as much light as possible. The star trails on 30 seconds exposure image is visible but they are not obvious when we downsample the image to lower resolution. Since I take closer view of Milky Way, star trails will be obvious on 30 seconds exposure, so I set to 15 seconds with astrophotography’s 500 rule. It is calculated by dividing 500 with equivalent focal length of camera which is 29mm on OnePlus 3, results in 17.24 seconds and I rounded to 15 seconds. At the same time I pushed the ISO up to 3200. With this setting, it gave me high noise Milky Way image on single exposure, I used image stacking (29 frames) to reduce the noise.

My setup

  1. Tripod
  2. Intervalometer App (to take multiple frames for image stacking)
  3. OnePlus 3 (Pro mode) : 15 seconds, ISO 3200, white balance in Daylight, focus to infinity, RAW enabled.

Results

Stacked of 29 frames, equivalent to 7min 15seconds exposure. There were thin clouds at the core area, 7min of exposure created motion blur on the clouds too.
15 seconds
30 seconds

Notice that the star trails on 15 seconds exposure are less obvious than 30 seconds exposure. For the editing in Lightroom, I pushed the Dehaze slider to the right about 80% of maximum and the opposite (-10%)  for Clarity slider. The reason I dragged clarity slider to left is to smoothen the image and make the stars a little softer, since the noise will be more obvious in cropped image. So close-up view of Milky Way with shorter exposure time is still within smartphone’s capability by sacrificing the resolution.

ISO 3200, 15 seconds (Stacked of 80 images and Post-processed in Adobe Lightroom) – Stacking of 80 images allows approximately 9 times noise reduction, more details and colors can be pulled out easily to create cleaner and more colorful Milky Way images

Workflow:

With the dual camera smartphones taking over the camera structure trend on smartphones, most flagships have secondary telephoto lens with focal length of 50mm (equivalent to full frame) to achieve optical zoom on smartphones without sacrificing resolution and this will definitely benefit Milky Way close up shots on smartphones such as Samsung Galaxy Note 8 and S9+.