Looking for some recommendations from the professionals here. I currently have a Canon T2i with the kit (18-55) and starter zoom (55-250) lenses. During the day, these lenses produce some great quality shots...but when it comes to panning at night... It's a crapshoot if something comes out well enough to keep. I was looking into the Canon 70-200 F4/L with IS as a possible option. Opinions?