Troubles with Canon G7...

[Slick Fork]

Something that was screwing me up was the angle the lens was facing the glass at.

For example if I was shooting through the glass at a 90 degree angle (camera was at the same height as the subject) then all my shots turned out great, however if I moved the camera above or below the subject so I was shooting at an angle through the glass I found I got blurry focusing.