I'm being stalked by a deranged finch!

This cute little finch has been trying to get into the house for two days now.
She is sitting on the window ledge and watching me.
Then she flies at the window and keeps tapping-tapping-tapping!
She's not crashing into the window like some do.
Just gently driving me crazy!
And it is very hard to get a picture of her.
As soon as your bring your camera up, she flits away.
Then she taps some more and flits away.