Wildlife photography is one of the more expensive kinds of photography, with some popular lenses costing over $10,000. For many photographers, trying to get close enough to the subject may require longer 600mm lenses, but when you consider the price for each of them, a little research can definitely go a long way. The Canon 600mm F/4L II is a little cheaper than the Nikon 600mm F4E; however, sometimes the price isn't a major factor when deciding which to buy.
In a recent video, Tony and Chelsea Northrup compare the "best" systems available from both Canon and Nikon to hopefully help you decide which is going to work best for you. Comparing the Canon 5DS R and the Nikon D850 with their respective 600mm lenses, they demonstrate results from each system. When it comes to sheer detail and clarity it seems both lenses, perform at a very high level and their differences are minimal at best. Northrup concludes that based on the lenses themselves, neither are going to disappoint and therefore it comes down to the camera bodies instead. The 5DS R does boast higher resolution; however, it lacks the better focusing system, dynamic range, and frames per second that the D850 has. Due to this, currently, it may seem that Nikon is the way to go for the best wildlife photography gear. Northrup does go on to discuss how both manufacturers tend to play cat and mouse and the update to the Canon 5DS R may address many of the missing features in the current model.
Check out the video to see the full comparison.