I first started to add White Balance tools in Blender because I was missing such tool for my lighting workflows. And I ended up making a more complete Camera add-on with exposure control, motion blur (using shutter speed or shutter angle), autofocus tools... And now I even added Physical lights with different physically-based units.
I learned a lot or Python and Blender API while doing it, it was really interesting. I'm still more a hacker than a real programmer, but I guess everyone has to start somewhere!
Photographer 3 Release - Added Physical Lights
Photographer 3 - Auto Exposure and Lens Tilt
Photographer 3 - Camera Target and Render Queue
Photographer 3 - Focus Plane debug
Photographer Blender Addon - Introduction
Photographer Blender addon - Motion Blur
Photographer Blender addon - UI and Preferences
Photographer Blender addon - Blender 2.8 and Autofocus Tools
Photographer Blender addon - Master Camera