Long Tailed Tit

These little creatures invade in gangs!As usual I'm downstairs doing chores when the ''Arrive'''and my cameras are upstairs! So off we go to fetch the kit and surprise,surprise they are still in the garden!The problem is they move so fast,but thankfully the D800 was set up with the Sigma tele zoom,so off I set in pursuit!
I managed to get about a dozen shots before they disappeared out of sight!They always look so puffed up and cuddly.They must weigh so little?

Nikon D800+Sigma 150-500@ 500mm,1/125 sec.@ f8,ISO500.

I have now found that the best setup when photographing birds in 'bad' light is to set Auto ISO in manual mode and have full control over shutter and aperture. With the D800 the ISO range and noise levels are so good,that it becomes a 3rd auto setting ?