Progressing from my last post, I learnt about how characters can have rigs for eye lights. I didn't have the time for Rocket Dog to sit and make a lighting rig for the eyes, so I had a makeshift alternative - a point light constrained to one of the controllers at the front. Lipin showed me how constraining to controllers (or as this tutorial video shows, a locator) can make the constrain work more reliably than constraining to geometry. This worked for the most part, but I had a new problem - even though the light was now generally moving where it needed to be, the dog looked like he wasn't really focused on anything in particular, and it looked floaty. And I wasn't able to move the light around and key it because of the constraint. I ended up checking out the different tabs for the constraint itself and found one related to offsets, with the ability to key on them. Again, moving the light in the viewport and hitting key didn't do anything. But it did provide me a key to work with in the graph editor, where I was able to tweak the curves as needed.
Eyes with no point light
Eyes with point light
Eyes with point light and the constrain offset keyed
In the future I would use area lights with a shape texture file to maintain the correct shape, size, and exposure of the lights in the eyes. I ran into minor issues with the point light varying due to movement and differing shots.