I have the 70-300L and needed more reach, this lens is great! I looked at the previous 100-400L, the Tamron 150-600 and then tried this out, it focuses way faster than the old one and is lighter and handled better than the Tamron and is built better. the close up capability of this over the others is way better too. I knew as soon as I picked it up and started shooting it was a fine lens. A little pricier than the others but if you can swing it just go for it, no buyers remorse wondering if I made the right choice here. I went for 18 month no interest on my Best Buy card to soften the blow a little. :-)

After doing much research, I finally decided to upgrade from my Canon EF 70-300 4-5.6 IS USM lens. I primarily shoot wildlife and enjoy going to airshows and was looking for a little extra reach. I took this lens out for a test spin at my local animal sanctuary and I was not disappointed! A few impressions -- First, this lens is HEAVY - much heavier than my 70-300, but not heavy enough to make a tripod necessary. Secondly, this lens is crisp. I took some of my cleanest, sharpest photos ever with this lens after my first day out with it. Though, I will say that it also produced a higher percent of soft images, that I would, at this point, attribute to user error. I also noticed a considerable gain in reach from going from 300 to 400mm. I was also impressed with the level of bokeh achieved at 400mm and 5.6. Overall, I couldn't be happier with my purchase. I feel like I have entered a new level of my amateur photography, and I am looking forward to learning more and growing with this lens for years to come.

This is by far one of the best lenses that I've ever used. I currently have a Canon 24-70L 2.8 and the 70- 200L 2.8. At this point, I am going to sell my 70–200 because this new lens is far superior to that. Even though it's a 4.0–5.6, it focuses very fast, the picture quality is fantastic and the reach is clean and beautiful up to 400 mm

Purchased this for the reach and optimum quality images needed for a recent 30-day trip to sub-saharan Africa and man does it deliver. Ended up being my walking around lens for the most part - superb reach for everything from ant trail macros to village life-in-motion captures to water fowl to sunsets over the zambezi and even a blood moon, nicely rounded out w/ the 1.4X extender to bump me up to 560mm. Found mine at a nearby store for a competitive price - well worth the money spent!

What an amazing lens this is! Mounted on a Canon 5D Mark IV. It focuses very fast. I primarily shoot wildlife and boating images with occasional sports photography. In any situation, this lens always performs. For larger distances I added the X2 extender which doubles the range. Howver, autozoom is disabled with the extender. It is pretty heavy and works best with a tripod. Overall this is an incredible lens that not only looks beautiful but performs each and every time. It made me excited to get back into photography.