[davidmanze]

I see the Tamron meanwhile as the better package, at least the second generation: The brake for any (not only just selected) focal length and the Arca foot which would cost another 200 € at the Sport are making the difference. The Tamron now also has a dock and believe me, it's complicated to adjust AF for ∞. Zooming handheld with the Sigma? Manual focusing without a tripod? You need very good luck...

 

But the foot of the Sigma is easily detached, it's just 2 screws to open.

 

We could also say, the Tamron G II is the result of the mistakes Tamron and Sigma did with 3 lenses before ^_^ I'm not counting Nikon's 200-500/5.6 

 

I just don't know why you want after your 500/4 now the zoom. You're not wanting that 100 mm extra, do you? A crop from the Nikon will serve as well. Why don't you get another body for shorter FL? I found the lens change with the Sigma demanding and not so quickly done in the field.

 Agree with your points in general and I'm shooting both formats, D750/D500.


The foot of the sigma is detachable and I took it off, with the four screws it weighs 108 gms, it's less in the way without it, for weight saving I think a generic lens-hood would do more to help lens balance.

 

   So far with my Tamron the AF has been spot on with the only errors coming from BIF.

 

  The Tamron came before the 500mm F4, and much as I love shooting with the latter it's 4.2 Kgs!! So it's a lens more for setup shoots out of the camper or with a back-pack. Another other thing is it's just that...500mm!  a lot of the time it's not quite enough and often way too much, I love shooting at F4 with melt away backgrounds and it's fine when you have the birds and your shooting but if there aren't many you get fed up lugging it around for no shots.

  In many ways I'm glad I tried the Sigma, it's a giant lens of beauty, but there just not enough advantages to make it a better practical lens than the G2. 

 I also have the "shoot out of the camper" plan, using 20 square meters of camouflage printed cotton to cover one side of the van completely , like a livable mobile bird hide, selling the G1 to my friend will mean I can treat myself to the G2, which I now think is the best practical tele-zoom out there.