After reading a few billion articles about Tamron and Sigma's 150-600, the last article I was reading had an advertisement along the side from a local computer store that would rent the lenses at $120 for 7 days. So I rented the Tamron G2, Sigma Contemporary, and Sigma Sport.

I take handheld pictures only of wildlife and landscapes; tripods are for videos and then only if the video will be more than 10 seconds. My rental goal was to determine if I could lug these behemoths for eight hours around the San Diego Zoo (100 acres), San Diego Zoo Safari Park (1,800 acres), Ramona Grasslands (4,400 acres), and the San Diego National Wildlife Refuge (11,100 acres). I could. No problem.

The Sport is supposed to take visually sharper pictures than the Tamron or the Contemporary. With my handheld pictures, I did not detect that visual superiority.

The Sport is waterproof, but I live in San Diego where it rains very little, and I don't do underwater photography.

What did affect things came down again to living in San Diego. It's sunny and hot here, and the Sport, being made of all metal, got excessively hot. It didn't seem to affect any controls or functions, but it sure got uncomfortable when I went to use that metal zoom ring. The Sport, then, was out, especially when I considered its $1,999 price versus the Tamron's $1,399.

That left the G2 and the Contemporary. Ultimately, it came down to the zoom ring. I use a Canon Rebel XSi, Rebel T2i, and Rebel T6s, and I have used a Tamron 28-300 as my walkaround lens for the last 8 years. So I'm used to how it zooms, i.e., zoom ring rotates left to right, 150 to 600. The Contemporary zoom ring rotates right to left, 150 to 600. When I was out shooting birds in flight, rapid zooming with the Sigma was uncomfortable because I'm right-handed, supporting the camera with my right hand and the lens and zoom ring with my left hand. That position allows my left hand to very naturally use the Tamron zoom ring. With the Sigma, I had to give up support of the lens in order to move my left hand into a position to comfortably rotate the zoom ring. I almost dropped the camera a couple of times, and I lost a lot of potential BIF pictures.

I settled on the Tamron G2. An extraordinary lens.

This all is in addition to my immediately-after-rental-review and my buying decision here: http://www.uglyhedgehog.com/t-458752-1.html

Note there are two of each Tamron and Sigma. The latest Tamron G2 seems to get most votes even when compared to the more expensive and weighty Sigma Sport.

But us Nikon people are wedded to the 200-500 Nikon. With D8xx cameras you can always crop to make up the extra 100 mm. The VR on the Nikon is awesome. I haven't seen it compared across the lenses.

You have 1/3 less pixels with a D750 but still can comfortably crop to 1/4 of the frame with good resolution....equivalent to a 2000mm when using the 500.