Flowers - Working DOF and Point of Focus

A favorite subject of mine to photograph is flowers. One of my workshop participants recently reminded me of why I love closeup photography so much.  Thanks Larry for your comments on how our eyes and the camera see the world differently.

For the past week I have been working in a local garden area where there is a patch of wildflowers.  Coneflowers, Butterfly Bush, Indigo, Blue Star, Aster, and many other local wildflowers of Arkansas are still plentiful even though it is already very hot and dry here.

When working flower closeups I find that managing depth of field is one of the most important creative tools that I have for showcasing the beauty of my subject.  There are always distractions and clutter around and behind my subject and how I include or exclude those elements has a major influence on the look and feel of my images.

Lets start by defining depth of field and examining how to manage depth of field (DOF) with the camera.  I define DOF as the area of an image that appears to be in focus.  Several factors influence DOF but the two that I will focus on are camera to subject distance and aperture.  In my work in this garden my camera to subject distance ranged from 1 to 5 feet using a Nikon 105 Macro lens.  The closer I am to the subject the more shallow the DOF and the more out of focus the background will appear.  The more I open up the lens aperture the more shallow the DOF and the more out of focus the background appears.

Here are a couple of examples of an image shot using different apertures.  The camera position did not change, I simply shot the two images at different apertures.

This image was made with the lens stopped down to its smallest aperture.

Nikon 105 macro  f40   .6 Seconds

This is the maximum DOF that the lens can deliver at this distance from the subject.  As you can see there is a lot of clutter in the background competing for attention with the main subject.

There are several possible solutions to reducing the background clutter but one of the most straightforward is to increase the size of the lens aperture, or "open up the lens". 

For this second image I opened the lens to its widest aperture.

Nikon 105 macro  f3.3  1/160 Second

The result is a very soft background where the flowers blend together to create a muted pastel background.  This background does not pull the eye as strongly and is much less distracting.

In photography, you constantly are making trade offs.  In this case I traded a cluttered background but the price I paid is soft focus on the main subject.  In the first image the main subject is sharp from front to back but in the second image only the front flower is sharp and focus quickly falls off making the second flower very soft.  This is the direct result of changing the lens aperture and is an example of the creative power you have in closeup photography.

Is soft focus on the second flower a problem?  There is no definitive answer to that question, only opinions.  I personally like the softness of the second image and prefer it over the cluttered background of the first image but neither presentation of the flower is right or wrong.  The power is in your ability to understand how to create a look with your camera and then using that knowledge to create an image that you visualize.

More later....