As far as capturing a group of birds in flight, there are two things you can do. In the first place, and I know there is disagreement in the forum, shoot shutter speed priority. Make sure you have a high enough speed to avoid blurring of the subjects caused by motion. Your focus method is correct, again, in my opinion. You ideally would like all the birds to be in the same film plane. In other words, each bird not in increasing distance from the sensor. If this is the case, a wider aperture would do. If not in the same film plane you would need to increase your f-stop (depth of field). In shutter-speed priority you can do this by increasing the ISO, but the down side is the higher the ISO, the greater the noise (or graininess of the image). There is a point where the distance between the birds (front to back) is too great and impossible to get all of them in focus. Bright lighting conditions can make things a lot easier, and it is quite possible to shoot 1/1600sec, F16, at ISO 400. As far as focusing the group, you need to pick a single bird, usually the closest is easiest. Technically (though near impossible to do) focus on one in the middle distance from the sensor which might allow ones in front and behind to be in focus. From a compositional point of view, all birds being in the same film plane is much better than a number of the same type of birds all in focus, but appearing to be different sizes due to different distances from the sensor. Also compositionally it can be advantageous to have a single bird as a focal point of the photo, and as long as it is in sharp focus, the other birds can be out of focus, and the degree they are out of focus would indicate how far they are from the viewer. Hope this helps~onlybill
I have included an image of flock of birds on the same focal plane. 300mm F5.6, ISO 100, 1/1600sec, shutter speed priority, center weighted metering
