Telephoto for 80D

[scottwheeler]

Just got a new 80D so I can capture sporting event photos for my high school kids.  I am an amateur photographer.  Need telephoto for football, baseball, softball and basketball.  Two questions:

1. What are best options?
2. Are there resources for finding used lenses?

[ebiggs1]

With the Tamron. I estimate a focal length of around 196mm at the 200mm setting when focused at infinity, 188mm at a focus distance of 10m and at 2m the focal length is reduced to around 140mm.  The Nikon AF-S 70-200mm F/2.8G ED VR II shows this effect quite strongly, and is greater than the Tamron lens.

The Nikkor 70-200mm f/2.8G ED VR II Lens is $2100 and the Tamron SP 70-200mm f/2.8 Di VC USD G2 is $1300.  I don't have the G2 but I understand it has significantly less focus breathing than its predecessor.  If you own Brand-N the choice should be obivious.  If you own Canon there is no choice. You have the best lens made in the 70-200mm range at your finger tips!