I've been away from wildlife photography for about two years, since when I switched to the mirrorless system. I still have the old Nikon D7000 and the 300mm ƒ/4, but frankly I've been totally unwilling to handle a large camera any longer. And I also can't stand an OVF any longer. But now I'm back into the game thanks to the Sigma 150-600mm ƒ/5-6.3 DG OS HSM C. After having tried it for the landscape — and loving it — a few days in the Alps gave me a couple of opportunities to get into close contact with wildlife.

What about the quality? I didn't run yet a test in controlled conditions about the sharpness of the new lens compared to the old Nikkor 300mm ƒ/4. Given that one of the latest subject was a marmot, I went and compared a similar shot taken in the past with the 300mm + 2x extender. The old photo was much better for the composition and took advantage of better light; the placement of the subject, at the border of a slope, made for a better separation from the background. But here I'm just interested in a rough comparation of the achieved sharpness, both for the IQ of the lens and my capability of getting an unblurred shot.

It's quite clear that there's the same amount of sharpness at pixel level — but the old photo was taken with a 6MP Nikon D70, the new one with a 24MP Sony α6000. That's twice the linear resolution (I recall that I stopped using the 2x teleconverter when I upgraded to more recent Nikon bodies, because it was unable to resolve enough for their higher pixel count). Furthermore, the stabilisation allowed me to use a longer shutter time and lower ISO, therefore a better noise figure.

So, I'm definitely back in the wildlife game, with even improved quality. At least for static subjects...