Three Little Coots In Focus

Last week I shared Birder2011’s shot of three American Coots with all three birds in focus.  Usually one bird is in focus and the other birds are not.  How would you get all three in focus?  The shot needs a two pronged attack.

First, your goal is to attain focus on the middle bird so you will need to use Spot Focus to specifically aim at that bird; otherwise the camera will tend to focus on the closest bird, leaving the ones farther away out of focus.

Secondly you need to widen your DOF (Depth of Field) to capture a larger front-to-back area in focus.  In order to get a better idea of the depth of field for your camera and lens you can use a DOF calculator online.  I found the Omni Calculator’s DOF Calculator to be easy to use.   I plugged in my sensor size (Canon APS-C), my maximum lens extension of 400mm, and a hypothetical focusing distance of 60 feet (20 yards is about as close to most birds as I can get).  I then put in my typical ƒ-stop of 5.6 and the calculator showed the following results:

ƒ5.6 at 60′
DOF: 1′ 4″
DOF Far Limit: 60′ 8″ (8″ behind the focusing distance)
DOF Near Limit: 59′ 4″ (8″ in front of the focusing distance)

As you can see from above, the Depth of Field is just over 16 inches from front to back.  Now let’s take a look at the calculations if the Aperture is adjusted to ƒ11:

ƒ11 at 60′
DOF: 2′ 8”
DOF Far Limit: 61′ 4.4″ (1′ 4.4″ behind the focusing distance)
DOF Near Limit: 58′ 8.4″ (1′ 4.4″‘ in front of the focusing distance)

By increasing the Aperture to ƒ11 we now have doubled the  DOF to 2 feet 8 inches.  So in the case of our three Coots below, assuming they were less than 3 feet apart and the focus was on the middle one, they all would be in focus.

If you enjoy seeing beautiful pictures of birds from around the world and reading about them Click Here to sign up for our mailing list.  Members can post their own GreatBirdPics and learn more about bird photography techniques.