It would be and outstanding, "a best buy" for a 6D. But, there is always a but, isn't there? It is a big lens that sits firmly in the super telephoto category. This means, it is BIG.
If you truly want one, you need to get it soon as it is a discontinued model. Hence the deep discounts available.
It can do this ...........
A Waxing Gibbous form a day or two ago.
I recently picked up that Sigma 150-500, and I love it. It's a lot heavier than what I am used to, which is why I use the tripod bracket as a "grip" for it, when I am hand holding it chasing after birds.
This shot is from the very first day I used it. Cropped to about 50%.
That is a very nice shot. Plus it shows how much the higher res of the 6D gets everything out of this mid-line lens. At full retail it wasn't such a good by but with the steep discounts and rebates offered on it now, it is a good buy.
Glad you like it and it lookslike you are mastering it. 
@Waddizzle wrote:I recently picked up that Sigma 150-500, and I love it. It's a lot heavier than what I am used to, which is why I use the tripod bracket as a "grip" for it, when I am hand holding it chasing after birds.
This shot is from the very first day I used it. Cropped to about 50%.
With results like that I'm getting one. Thanks
@ebiggs1 wrote:That is a very nice shot. Plus it shows how much the higher res of the 6D gets everything out of this mid-line lens. At full retail it wasn't such a good by but with the steep discounts and rebates offered on it now, it is a good buy.
Glad you like it and it lookslike you are mastering it.
Thanks, guy. Coming from you, that means something to me. I've also taken some pretty good moon shoots with it, including the recent lunar eclippse.
Mastering the lens? That shot was among the first two dozen shots that I took with it, and it was handheld. I think i'm getting better at using a DSLR camera, in general. I've been hearing "great shot" a whole lot lately. Photography is an old hobby, that I have revived lately to get some walking exercise. I had an old Konica with an old Vivitar Series One, 70--210mm.....the good version of it would seem. This Sigma is a LOT heavier than that old Vivitar, which is still in near mint condition.
The IS system on the Sigma 150-500 works fairly well for such a long lens [i guess, I have no comparison lens], but it can get into a tug-of-war with the AF system If you're trying to lock focus while moving the camera suddenly. I can hear it laboring, which cannot be good. Armed with that knowledge, you can get some pretty decent photos with it.
