D is for Differential Focus

Nikon D60 with lens at 200mm: 1/400 second @ f/5.4 and ISO 400

Differential focus is when only a small area of an image is in focus and the remainder is blurred, allowing the subject to be isolated. This is one of my favorite techniques and I intentionally blur portions of many of my images in order to emphasize my subject or to add to the story without shifting focus away from my primary subject. By using a wide aperture like f/4.5 or 5.6 (or f/2.8 if you're lucky enough to have such a fast lens) and focusing carefully i.e. manually, you can separate your subject, like this crocus's stigmata, from the background of it's blurred petals. This also works to blur an otherwise messy background into a sea of color that surrounds the subject. (Wasn't I lucky that purple and yellow are complementary colors thus providing a very pleasing contrast in the photo below.)

Nikon D60 with lens at 200mm: 1/125 second @ f/5.6 and ISO 200

In "C is for Composition", I said that "Photographers have a multitude of decisions to make about light, lines (leading or otherwise), balance, motion, space, focus, perspective, and framing." Focus, differential or otherwise, and its partner depth of field can play a large role in the composition of an image.

Nikon D7000 with lens at 112mm: 1/13 second @ f/5.6 and ISO 100

In this image of the cocktail nuts, I wanted to ensure the focus was on the nuts but within the context of entertaining and what better way than to show some hors d'oeuvres but allow them to be blurred while ensuring the nuts are in sharp focus. A shallow depth of field created with the f/5.6 allowed the blur I wanted while I focused on the nuts.

Nikon D90 with lens at 90mm: 1/250 @ f/5.6 and ISO 400

Lastly, I used differential focus in this image of the sunflowers to tell the story ... to focus on the bloom with the colorful images of what it will become blurred in the background.

Play with differential focus and share your images on the Light, Lines & Color Community in Google+. If you're not a member, join - it's free. Then just ask to become a member of our little community - we love to share and learn.

 

Comments

[bethacomer]

Can this technique be used with autofocus? Or is manual focus necessary? I continually have trouble with manual focus because my eyesight is just not that keen without reading glasses, which are clumsy when taking photos

[Claudia]

Auto Focus should work very well.