The settings below are specific to Nikon DSLR's but Canon & other cameras can achieve the same with slightly different settings but the principal is the same.
What I do is set the camera to aperture priority. I want to be able to control the depth of field so this is a must. However, for fast moving wild birds you need a very fast shutter speed, so how do you get both?
Set the camera to AUTO ISO with the following custom settings:
- Set the ISO to a base of 100. This ensures that if the light is good the ISO stays low.
- Set the minimum shutter speed to 1/1600. Yes....1/1600
- You can set the max ISO to 3200 just to ensure that it doesn't go over that but you can leave it off too, 6400 is usable if the exposure is spot on. I use a maximum ISO of 1600 just to ensure the image quality will be good enough for printing if I happen to get a "keeper".
Now with this setting the camera will never drop below 11600 of a second shutter speed, when it does then the ISO will automatically kick in and maintain the shutter speed of 1600.
What really makes this work well is in auto ISO it will increase in micro steps and not full stops like when you set it manually. So you could get an ISO setting of 320 or 450 etc.
Make sense? I have this saved as my bird mode. I use it exclusively when shooting birds in flight.. Always a correct exposure and the speed to freeze the action. And you choose the aperture...which is important.