My problem is my little monster (you'd have to know her) (and I have the scars to prove it) is usually too close for the lens I have on, and soon as I turn to look at her she walks toward me...no chance...then she's too far away for the 50mm...I eventually got a couple of shots but it wasn't easy. In this one she came over and decided to lay down in front of me while I was trying to get some mushroom shots...you can see those in the background...I had to back up a little, she was too close for even the 50mm to focus...but she actually sat there for a minute and let me get a picture.
For this shot I had the Makinon 135mm on and she decided (for once) to lay out in the yard a few feet away and was rolling around in the grass, I tried about a dozen shots and this is the only one that was decent. Usually if she decides to sit in a decent location she's facing away and refuses to look in my direction...Now that I think of it, this might have been the Lentar 135mm...
As mentioned above, I prefer daylight and manual focus. Forget about flash, it results in bright green reflections. Not good...Same as red eye but bright green...
When I tried to get film shots of her as a kitten it was almost impossible. Moved too fast, almost never got decent focus. Best time to try is when kittens decide it's naptime.