Young Collared Dove

Trying to get a Blip between showers was getting very difficult today.All the birds had taken cover,but luckily we had a break in the rain and at least the Doves came out for some food.
I took my D800 & Big Sig to my local camera technician today to have it AF Fine tuned.It has been much better recently but I think there is still more to be had in terms of quality? We shall see!
In the meantime I have to use my D3 + 170-500 Sigma.
I was quite surprised at the quality really ( See spec.) And this is wide open and hand held @ 1/500 sec.