The light was much better today. This meant that I could set my camera to have a combination of fast shutter speed – at least 1/3200 and a good depth of field.  This is the combination you need to freeze the action of birds in flight.  Usually, anything less than 1/3000 will not be fast enough. Quite often you may have to adjust the sensitivity of the camera – this is the ISO – and then you will get speckly images, this is called noise.  To get rid of this you need small ISO numbers but then you won't get a fast enough shutter speed, hence the need for good bright light for flight shots. Today it was bright.