The Canon 600mm f4 non IS lens is the first version of Canon’s 600mm range, yet the quality of the optics is still awesome. It is very heavy and not something you hand hold. I often use it coupled with either the Canon 1.4X III converter or the 2.0X III converter. With the Canon 7D Mark II it will still Auto focus with both the 1.4 X and the 2.0X. With the 2.0X added you get some serious reach at 1200mm f8. With a lens of this reach, I find that my field craft is really tested. Even a slight breeze will cause enough shake to cause image degradation. This is particularly evident if the subject is further away. There is a slight quality lose when the converters are added, however the quality is still better than most lenses anyway. Minimum focus is 6m which I find is ample in most circumstances. Due to the weight of this lens I mount it on a Wimberly Gimbal head and a quality aluminum Gitzo Tripod. I tend to use an aluminum tripod as I have found the carbon fiber versions tend to wear and gum up when used on the beach and in the mud.