As a workaround, the following example AppleScript code, shown further below, will do a Save As… and select JPEG and can be used in an Automator Service with a Run Shell Script action and a keyboard shortcut assigned to it in: System Preferences > Keyboard > Shortcuts > Services
For testing purposes, in macOS High Sierra, I used: ⇧⌘J
NOTE: This may also ...
No easy preference or key is known to change the defaults. Barring a new discovery, plan to use a different app or script image conversion with automation.
You probably already know you could make a keyboard shortcut if an Apple menu to save as JPEG existed, but that’s the crux here. Other questions here have useful details on automation and using python ...
I will share my method. It is hard (thanks Apple for ignoring us on this!) but it works.
I'm assuming you are not using a "referenced library" as noted elsewhere here, but are importing all images into the Photos library. I might switch to a referenced library actually. But for now, this is how I do it.
In a non-referenced imported image library, note ...
This works for me in MacOS Catalina 10.15.2:
Open a new Finder window;
Resize the window to the size you want (however don't move the window to your desired location yet);
To lock the location and size:
start by pressing the Command ⌘ and Alt / Option keys together and drag the window to your desired location;
release your mouse button first then release ...
Just pointing out that the latest driver (from April 2014) for the UD-H01 (same for A-H01) still works fine for me with MacOS 10.14.6 on a Macbook Pro from 2015.
It's important to follow TEAC's install guide (updated 2018), i.e. don't forget to enable the kernel extension after the system reboot.
Since the CoreAudio driver of MacOS works "somewhat" (for me ...