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Tuesday, May 25, 2010

Isolated Sharpness

Tips and techniques for using shallow depth of field to add impact to your macro shots

This Article Features Photo Zoom


When experimenting with selective focus, think about the colors in the background. By making that background go very soft, you can create interesting color compositions like these two images. While the main subject is the same, image 4 is a color-opposite color composition, and image 5 is a monochrome color composition.
Challenges With Shallow Depth Of Field
Focus carefully. Depth of field is narrow when you’re doing close-up and macro work anyway, and with the shallow techniques described here, you’re guaranteeing an always narrow band of sharpness. Choose where that sharpness is very carefully.

This often means using manual focus. Autofocus frequently puts your depth of field at random places when you’re up close. You may think it looks okay in the LCD review, but unless you magnify that image (and I often do), you can be fooled. It’s frustrating to look at your photos on the computer later and discover that focus is on the wrong part of a flower or the hind end of a bug instead of its eyes.

You can use autofocus up close for the effects seen on these pages, but you need to lock focus and not allow the autofocus to continuously find new points to focus on. Most cameras lock focus by a half push of the shutter release. Some have special buttons on the back of the camera that you can use. Lock focus, then if focus is a little off, move the camera closer or farther from the subject to refine focus. That’s also a good way to work with manual focus.

Since you’re shooting with a large aperture, you’re usually using a faster shutter speed and don’t necessarily need a tripod. Since focus point is so critical, I find that using a shallow depth-of-field technique is difficult when using a tripod, so I usually don’t. I need to move, often even moving with a blowing subject.

Look for distractions along the edges. The shallow depth of field effect can be so strong and so overpowering as you look through the viewfinder or on the LCD that you miss something important—sharp distractions around the edge of the image that can fight with your sharp subject. Be careful of what’s sharp in your photo besides your subject. Look at those edges and be sure you haven’t inadvertently included something sharp that shouldn’t be sharp. You may have to check your LCD review to be sure the edges aren’t a problem.

Anytime of year is a great time to experiment with this technique. I’ve used shallow depth of field over the years for everything from snow crystals to dew. I have to admit, though, that my favorite subject for this approach to photography is a flower. That’s when you can especially play with all sorts of in- and out-of-focus colors and tonalities.

Extension Tubes And Limited Depth of Field
An easy and inexpensive way to get quality close-up and macro images is to shoot with extension tubes. Extension tubes are simply tubes that fit between your lens and camera body, and have no optics in them, only connections for the lens electronics. With them, any lens will focus closer—how much depends on the thickness of the extension tube and the focal length of the lens.

They also work great for getting shallow depth of field. They don’t cause the shallow depth of field, but they do allow you to use any telephoto as a “macro” lens (including zooms). Using a telephoto up close will give you shallower depth of field because telephoto focal lengths have inherently less depth of field and getting closer to the subject gives less depth of field. (Wide-angle lenses often won’t work with extension tubes.)

Being able to use a telephoto up close is a great benefit because it increases your options as a photographer. With extension tubes, you’re not limited to the focal lengths available in macro lenses. Plus, adding extension tubes to your bag takes little space and weight, and costs you a lot less. ABOVE: Kenko DG extension tubes

Rob Sheppard’s new instructional videos on Lightroom and more are available at www.robsheppardphoto.com.


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