Sigma 50-500 or Canon 70-300 with 2x converter?

[MrLogic]

How about the $1275 EF 300mm f/4L IS USM?

Add a 1.7x TC and you have a poor man's 500mm. Popular with birders. I wouldn't be surprised if that combo provides better IQ than the Sigma 500mm zooms @ 500mm*. Then again... maybe not.


* Both lenses are at their weakest at the tele end... hardly unusual for tele zooms, even the best ones, such as the Canon 100-400, Nikon 200-400 and the Sigma 300-800 suffer from this. Extremely annoying, IMO.