The Pixel 4 is Google's first smartphone to have multiple rear cameras. Unlike many other competing flagship smartphones that offer both ultrawide and a telephoto cameras on the rear, the Pixel 4 only has a secondary telephoto camera. To its credit, the Pixel 4 uses the telephoto camera to great effect. It not only enables better portrait mode shots and ~2X zoom, but also allows users to take up to 8X zoom shots with minimal loss in quality thanks to Google's Super Res Zoom algorithm. Google likely limited the Google Camera app to 8X zoom because going any further will reduce the quality of the shot, but that doesn't mean zooming in any further will result in useless photos. On the contrary, it's possible to take 16X zoom shots on the Pixel 4 that, in my quick hands-on, seem to be okay.

XDA Senior Member cstark27, best known for his work on modifying the Google Camera app to enable new features on older Pixel smartphones, discovered a way to not only increase the maximum zoom in the app but also use the telephoto camera at higher zoom levels. Installing this modified app with the higher maximum zoom limit on the Pixel 4 (and other Pixel smartphones) doesn't require root since the package name is different than the original Google Camera app. However, if you want to use the Pixel 4's telephoto camera at zoom levels higher than 8X in this modified app, you'll have to root your device.

Left: Settings page in the modified app. All custom settings are found in "PX Mod Settings."Right: "PX Mod Settings" page, where you can set the maximum zoom level and other settings.

In order to enable the telephoto camera at higher zoom levels, you'll either have to flash the Magisk Module provided by cstark27 or enter the following shell command:

        adb shell su -c "setprop persist.camera.maxzoom 51"
    

If you haven't granted root access to the shell yet, then go ahead and grant it access when prompted. After entering this command, force close "Camera PX" (the modified Google Camera app) or reboot your Pixel 4. This property controls the maximum zoom level that the telephoto camera will be used for in the Google Camera app. If you don't set this property, then zooming in past 8X will kick you back to the main camera. The value of "51" was chosen here so you can increase the maximum zoom level in the app up to 50X, but I don't recommend going above 16X if you want usable photos.

Here's a Google Photos album containing some shots I took today (including the ones shown earlier):

Google Pixel 4 16X Zoom Sample Photos

For any questions or feedback about this mod, check out cstark27's thread on our Google Camera Mods forum. This post in his forum thread has the download link for the Magisk Module and the latest version of his modified Google Camera app.

Google Pixel 4 Forums ||| Google Pixel 4 XL Forums

A non-root version of this mod enabling the use of the telephoto camera past 8X zoom should be possible, but it'll likely take some time to accomplish since the property is read in a library. We'll keep an eye out for further developments on this mod and will let you know if the modders figure it out, though.