So I'm out at the Albany Shoreline after work yesterday with the 20D and Sigma
800 f5.6 shooting shorebirds and misc others. I see a California Towhee on a fence
20 yards away and take a shot. Low light so the camera set at 800mm, ISO 400, f5.6
AV mode. The shot is at 1/640 sec, a lttile slow but still get a good shot. The DOF
is about 4 inches and isolates the bird quite well.
1 Single Towhee on fence (probably female)
Sharp detail, good color and bokeh, not too much noise; all you can ask for from a
lens. Then a mate/suitor shows up and they start to dance. No time to adjust the
ISO, so I shot at the same f-stop.
2 Exchange greetings and bows (great focus on the hind quarters of the male?)
3 Puff up like a Sumo and flap and squat
4 Throw in a little flapping and shimming
5 Bow to the left
6 Bow to opposite sides (focus on the center = neither in focus!!!)
7 Bow to the rear
8 Bow and twirl, and it's over.
Now with the 800 (on a monopod), if I was able to bump the f-stop to f11 and get the
ISO to 1600 (to keep the same shutter speed) I could have gotten a DOF of about
8 inches. Which might have gotten them both in focus. With my 500 f4.5L at f5.6
and 20 yards the DOF would be around 11 inches, definitely good enough for this
capture.... So you give up DOF for reach and subject isolation. Which do you want?
