Saturday, June 25, 2016

Astrophotography With A Phone - LG G4 & High ISO

Stars Above Sharps Hallow - Morgan, Utah
ISO 1000, f/1.8, 30 Seconds, LG G4.
Astrophotography with a cell phone? Sounds impossible. But is it?

I got a phone adapter for my tripod, and I thought to try it out photographing stars. Utah has some of the best sky for astrophotography because once you get away from the towns and cities, there is almost no light pollution. Astrophotography requires a dark sky in order to really capture the stars.

My new LG G4 has manual controls, including up to 30 seconds exposure, and can save in RAW. I knew that high-ISO is not a strong point for the G4 because of its tiny sensor, but thought to give this a try anyway.

After finding a dark spot, I set the phone on the tripod and got the settings in order: ISO 1000, 30 seconds exposure, and manual focus to infinity. The aperture is permanently set to f/1.8, but that's a good f-stop for this kind of photography. I didn't worry about white balance because that's easily adjusted in post-processing. I also set the self-timer to three seconds just to avoid any camera shake.

Once the shutter was open, I used an LED flashlight to "light paint" the foreground hill. It was dark and would have been almost entirely black if I had not done this.

The results? Mediocre. But better than I would have guessed.

The LG G4 has a practical high-ISO limit of ISO 600, which is quite good considering that the camera has 16 megapixels stuffed onto a tiny 1/2.6" sensor. Going above ISO 600 is going to produce less-than-stellar results. ISO 1000 is the highest you'd ever want to go with this camera, and the digital noise at this ISO is too much for my tastes.

A long exposure, however, adds even more noise because the sensor gets hot. Most digital cameras offer long-exposure noise reduction to compensate, but not the G4. So you have noise on top of noise.

I post-processed the RAW file using Alien Skin Exposure X. It was a tough balancing act between noise reduction and sharpness. I think the largest that this photograph could be printed is 8" x 12" and that may be pushing it. For internet viewing it's alright.

Here are two more images captured with the LG G4 that same night, post-processed using Google's Snapseed:
Night In Weber Canyon - Mountain Green, UtahISO 1000, f/1.8, 30 Seconds, LG G4.
Nighttime In Sharps Hallow - Morgan, UtahISO 1000, f/1.8, 30 Seconds, LG G4.
As you can see, Snapseed didn't do a great job with these images. I've been impressed with Snapseed otherwise, I just don't think it had a lot to work with here. The LG G4 just doesn't produce good files at ISO 1000.

Amazingly, it's possible to do astrophotography with a cell phone, and the LG G4 is one of the best options for this. But it's not really all that practical, as the mediocre results make you wish that you'd used a better camera--one with better high-ISO capabilities. 

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