📱 #11: Orion Nebula with a Smartphone

🌌 A New Approach: DSO Imaging by Smartphone

It was a clear and freezing evening — the kind that practically demands a session with Orion. But instead of reaching for my usual gear, I decided to try something different: capturing a deep-sky object using just my smartphone.

📷 Acquisition

The target was M42, the Orion Nebula. The camera: an LG G4 with an f/1.8 lens. I had to figure out some things on the fly — most importantly, the maximum exposure time before star trailing would ruin the shot.

I remembered the 1/400 rule: divide 400 by your camera’s focal length to estimate the longest exposure you can get away with. The problem? I had no idea what the smartphone’s effective focal length actually was. So I had to experiment.

After some trial and error, I landed on 20-second exposures at ISO 400. It struck the right balance — stars became visible, and the background remained dark enough to keep things clean. I managed to take around 10 light frames out in the cold, followed by 5 dark frames.

For the darks, I pressed the phone’s lens into a carpet to block out all incoming light. Not ideal, but it was the best I could do at the time.

🧪 Lessons Learned

Taking dark frames with a smartphone is surprisingly tricky. Even with the lens pushed into the carpet in “total darkness,” a bit of light still found its way in. Maybe black tape or a custom lens cap would help next time.

Another mistake: I had accidentally shot everything in .jpeg mode. As a result, DeepSkyStacker threw up a warning — stacked processing needs uncompressed raw images to work properly. No stacking this time. The image above is just a single 20-second exposure, processed in GIMP2.

📱 Smartphone Again?

Absolutely. The best camera is the one you have with you — and this one managed to pull out some visible nebulosity right where M42 lives (just below Orion’s belt). It’s not clean, not sharp, and certainly not stacked — but it works. And the LG G4 can shoot in .raw format, which opens up new possibilities for future attempts.

So yes — smartphones can do DSOs. Not easily, not perfectly, but they can.

Clear skies,
Chris