Thanks James and Roger. I did have a chance to test it out for "action" dog shots today and it's just too long for my yard shots which means it will also be too long for ring shots. Most of what I shoot in the ring is shot at 85 to 110 mm on the 70-200 zoom or with my 100 macro and the same holds for my yard play shots where I work on my technique. The Tamron 150-600 is just too long. And with a F5 max aperture, it would not work at all for indoor ring shots.

So for me, this is a specialty lens. It would be great for my nature and wildlife photography but of little or no use in my business which makes the purchase a bit more difficult to cost-justify unless or until I get my nature/wildlife photography contributing a greater portion of my business revenue.

I suspected this was the case before I tried to use it for the yard shots but it was almost laughable. When I tested the 100-400 Canon zoom, it worked just fine for action shots but the 300mm F4L was also too long so it's not that there's anything wrong with those lenses. They just aren't going to work for that particular application and since there aren't that many of us doing that, I doubt the lens manufacturers are losing any sleep over it .

So, my summary: the Tamron 150-600 zoom is a quality lens that takes excellent images for what can only be considered a bargain price. It is not the Canon EF 600mm F4L IS II but it also isn't $13,000. And, unlike the big Canon, it's a zoom which gives you more cropping options as well as some outstanding IQ in the other telephoto lengths ranging from 300mm through 500mm. It's big. It's heavy. It has weather-sealing. It has a very good Vibration Control system which allows hand-holding for those with strong arms . If you make a living or a hobby of shooting nature and wildlife, this is a bargain you should consider for great quality images at a very reasonable price.

Jim