Nikon D5100 back button focus question

[annamaria]

Hi all, I have a question. I've been trying out the back button focusing which I assigned to the AE button in the rear of the camera. My question is this: Let's say for example that a Cardinal is munching away at the bird feeder, and I have locked focus on the bird, but then he flies to a nearby tree. Do I keep my finger pressed on the AE button during the whole process from bird feeder to the tree as the bird moves? Or do I just press once only to lock focus, and let go of the back button, and fire away from the feeder to the tree. I can't seem to get tack sharp focus that I would want. Any help is appreciated.

 

[KmH]

I don't see a photo.

 

[weepete]

I normally keep it pressed if it's a moving animal with continuous focus on. Unless I'm using the BBF to pre-focus on an area in which case it will depend if the depth of field is large enough to cover the movement of the bird.

 

[annamaria]

I don't see a photo.

Sorry I was just mentioning the cardinal as an example. I deleted the shots I took today. Maybe another day when I get the chance will post one.

 

[annamaria]

I normally keep it pressed if it's a moving animal with continuous focus on. Unless I'm using the BBF to pre-focus on an area in which case it will depend if the depth of field is large enough to cover the movement of the bird.

Thanks for your thoughts. Got to keep on practicing and experimenting.