A shallow depth of field is a great way to focus attention on part of a scene by transforming the background into wonderful bokeh, which is why it’s a classic technique for portrait photography.
Normally you’d achieve shallow depth of field with a wide aperture of around f/2.8 or f/4. But aperture isn’t the only factor in shallow depth of field.
Focal length and the subject’s distance from the camera also play a part in giving your images a shallow depth of field.
The longer the lens and the closer the subject, the more of a shallow depth of field effect you will achieve.
Captured at f/4 with an 18mm wide-angle lens, the background in this scene is fairly sharp. We can employ Photoshop’s Gaussian blur filter to fake a shallow depth of field, focusing attention on the figure and blurring distracting details.
By applying different strengths of blur to duplicate layers then restricting the effect with Layer Masks, we can create a fall-off of sharpness either side of our digital focus point.
How to fake shallow depth of field
01 Select the figure
Open your start image. Hit Cmd/Ctrl+J four times to make duplicate layers. With the Quick Selection tool, paint over the figure. Use ] and [ to resize the brush. Hold Alt and paint to subtract areas from the selection. Go to Select>Refine Edge. Set Smooth 10, Feather 0.5 and hit OK.
02 Add to the selection
Go to Window> Layers to access the Layers panel. Rename the top layer ‘Sharp’. Grab the Selection Brush tool, set Mode: Mask and pick a soft circular tip. Paint over areas that would be the same distance from the camera as the figure to add them to the selection.
03 Create layer masks
Click the Add Layer Mask icon on the Layers panel to turn the selection into a mask. Highlight the layer below. Go to Filter>Blur> Gaussian Blur. Set Radius 1.5px. Hit OK. Name the layer ‘blur 1.5px’, then hold Alt and click the Add Layer Mask icon to add a full black mask.
04 Reveal the blur
Grab the Brush tool and set colour to white. With the layer mask thumbnail on ‘blur 1.5px’ highlighted, paint over the foreground and tree. Highlight the layer below, rename it ‘blur 3px’, apply the Gaussian Blur filter at that value, then Alt-click the Add Layer Mask icon again.
05 Apply stronger blur
Paint with white to reveal the stronger blur on the ‘blur 3px’ layer in the grass and scene behind the tree. Next highlight the layer below. Rename it ‘blur 6px’ then apply the Gaussian Blur filter at that strength to make the trees in the background appear more out of focus.
06 Boost the tones
Finally, use Adjustment Layers to boost the tones. Highlight the top layer, click the Create Adjustment Layer icon on the Layers panel and choose Brightness/Contrast. Set Brightness 6, Contrast 12. Next add a Hue/Saturation Adjustment Layer and set Saturation +7.
PHOTOSHOP CS BLUR GALLERY
While the blur filters available in Photoshop Elements can give realistic results, Photoshop CS6 offers more options. In particular, the new Blur Gallery has three filters that are designed to mimic shallow focus and tilt-shift effects, with greater control over the look of the digital bokeh. The new filters make it much easier to create the fall-off of sharpness achieved here with different strengths of blur.