Problems with rapid iteration timers

It seems like timers in Corona have certain limitations.

I have a game where I am manually tweening objects down a screen and I am stepping through this animation process once every 0.03 seconds.

I’ve noted that at 60FPS, if I change the timer interval down from 0.03 to 0.018, it does not get any faster at all.

And then, when I move it to 0.016, it takes a huge leap forward and gets out of hand.

So my question is, why does this happen, and can it be fixed or circumvented?
Secondly, and less important, the reason I did manual tweens is because I wanted to ensure my graphics were drawn at whole pixel values so that they maintained their sharpness… is there a tweening library available that can do this automatically?

*NOTE* Yes, I have transcribed the millisecond values I put into the timers into whole seconds for the sake of readability. 0.03 = 30 milliseconds. [import]uid: 7473 topic_id: 11608 reply_id: 311608[/import]