I know this has bee a big discussion and thought this might help somebody. Just a little test I did today so I can justify my purchases to myself. Mainly the 70-200MKII and 2XTeleIII. First pic is where I was standing in relation to the subjects. I think the description of all the pics are under them minus the first pic. Hope this helps so others. Oh, these are SOOC and 100% crops on the ones that were cropped and maxed out at 300mm on the 70-300 and 400mm on the 70-200+2X.
IMG_4768
IMAGE LINK: http://www.flickr.com …/11274294@N03/7055170699/
70-300USM-IS
IMAGE LINK: http://www.flickr.com …/11274294@N03/6909080502/
70-200MKII+2XIIITele#2
IMAGE LINK: http://www.flickr.com …/11274294@N03/7055171913/
70-300USM-ISCrop
IMAGE LINK: http://www.flickr.com …/11274294@N03/7055171963/
70-200MKII+2XIIITeleCrop#2
IMAGE LINK: http://www.flickr.com …/11274294@N03/6909081276/
70-200MKII+2XIII
IMAGE LINK: http://www.flickr.com …/11274294@N03/7055171211/
70-200MKII+2XIIITeleCrop













****IM SELLING:: practically NEW 
