Pixel 3a Astrophotography

Introduction

I came across some intriguing insights regarding the application of Smartphones in Astrophotography. Specifically, I stumbled upon detailed information about the remarkable 'Astrophotography' mode embedded within Pixel Smartphones. While I was already acquainted with the 'Night Sight' mode on my Pixel 3a, with the understanding that it mainly prolonged exposure for better performance in low-light scenarios, I discovered a feature hidden from me in plain sight. When the Pixel 3a is taken into an environment with reduced ambient light, pointed skyward, and stabilized either through bracing against an object or securing it on a tripod, an intriguing mode change occurs.

The familiar 'Night Sight' Moon icon on the shutter button changes into an icon depicting Stars. Upon a careful press of the shutter button - as bumping the phone before landing squarely on the shutter 'button' results in a return to the Moon icon and switches off the 'astrophotography' mode - an intricate procedure spanning approximately 1 minute (4 minutes for Pixel 4 and above) is initiated. Within this timeframe, the camera undertakes a sequence of exposures, dynamically stacking them. This stacking mechanism synergistically enhances image quality and luminosity. What's more, the process integrates sophisticated AI-driven post-processing algorithms, adding an extra layer of finesse to the final output. See 'Astrophotography with Night Sight on Pixel Phones (Nov. 2019 - Background to development by Google)' in the 'Links' page for a detailed account of the process as well as design parameters.

Each exposure for the Pixel 3a on hand appears to be about 4 to 5 seconds in duration. Although the on-screen timer starts at around 60 seconds and counts down, the process ends when the timer reaches about 12 seconds remaining. Attempting to count the number of exposures by watching the updated image on the screen gives maybe 8 or 9 exposures.

Index

Simple Tripod and Smartphone Holder

This simple setup consists of a basic, lightweight tripod (Otto brand - $AUD30)  to which a smartphone holder is attached. The light weight and wide angle view of the Pixel 3a makes it easy to point the camera towards the point of the sky of interest despite the coarse position adjustments available with the tripod.

Pixel 3a on tripod - 'Astrophotography Mode'

Example result - Pixel 3a 'Astrophotography Mode'

Bluetooth Remote Shutter Release

As explained above, the Pixel 3a must be held perfectly stationary to enter - and stay in - 'astrophotography mode'. To start the exposure in that mode the shutter icon on the Pixel needs to be pressed. In general - and in particular at a pointing close to overhead - it is difficult to approach that shutter icon smoothly. To avoid the contortions necessary to press the shutter icon (and the occasional drop out of 'astrophotography mode' due to vibration) the Bluetooth remote shutter control which came with the Otto tripod is paired to the Pixel 3a - allowing initiating exposure runs without touching the Pixel 3a.

It has an ON-OFF switch and is rechargeable via a USB-C connector.  The Otto tripod ($AUD 29) comes with one of these and at that price it is worth buying the tripod just to get the remote shutter !  If you are prepared to wait a month or two the remote is also available on eBay for around $AUD 3.

Basic Astrophotography with the Pixel 3a

Describes the operation of the 'Astrophotography Mode' of the Pixel 3a. The simplest method is shown ('point-and-click') and the subsequent results are given.

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Astrophotography_With_the_Pixel_3a_Smartphone.pdf