Photoshop Lens Blur: take precise control over depth of field post-shoot
When shooting a small object up close, you can adjust your lens’s focal point manually so that your subject’s key details look sharp, while the rest of the features gradually soften into a delicate lens-induced blur (or bokeh). This bokeh effect can enhance an image by creating an abstract background blur that complements colours and details in sharper areas and draws attention to a specific part of the shot.
Getting the focal point spot on can be tricky, especially if you’re shooting with a wide aperture such as f/4. But don’t panic, because there is another way.
By capturing the image above with a tight aperture of f/22 we were able to get more of the watch in sharp focus, and then control the depth and the intensity of the bokeh in Photoshop.
Here, we’ll show you how to mimic a realistic bokeh using Photoshop CS5’s sophisticated Lens Blur filter, which can add the natural-looking blur effects produced by various lenses.
By applying the blur to a separate layer you can control its intensity and then use layer masks to make the blur blend in gradually, just as it would when shooting with a wide aperture f-stop, such as f/2.8.
By applying the Gradient tool to the layer mask you can take precise control over where the sharpest areas begin to blend with the bokeh, so that you can recreate different depth of field effects without fiddling with the camera’s aperture settings.
Step by step how to use the Photoshop Lens Blur filter
01 Add a layer mask
Open your start in Photoshop. Go to Window>Layers, double-click on the locked Background layer thumbnail, then in the New Layer window hit OK. Click the Add Layer Mask icon at the bottom of the Layers palette and a white mask will attach itself to the layer.
02 Set up the Gradient tool
Grab the Gradient tool from the Tools palette. Press D to turn the foreground and background colours to the default white and black. Click on the Gradient Editor and select Foreground to Background. Hit OK. Click on the Linear gradient in the options bar.
03 Draw a gradient on the mask
Drag upwards to draw a white-black gradient. White makes the pixels solid, grey semi-transparent and black transparent. Grab the Brush tool and set Opacity to 24% and Foreground Colour to Black. Spray on the mask to make the lower corners semi-transparent.
04 Add lens blur
Click back on the image layer and go to Filter>Blur>Lens Blur. Set the sliders to 0 to see what each one does. Tick Faster, then go to Depth Map and set the drop-down menu to Layer Mask. Tick Invert and set Radius to 96. Masked areas will become blurred.
05 Add specular highlights
To add realistic specular highlights to the bokeh, drag Brightness up to 27. To limit the blown-out highlights to just the brightest reflections, increase the Threshold to 235. Experiment by changing the Iris shape to Square (4). This creates a realistic four-sided specular highlight at the top of the watch.
06 Go with the grain
To make the clean bokeh areas look like they were blurred in-camera, raise Noise Amount to 2 pixels. Choose a Gaussian distribution, then click OK to create your natural bokeh effect. You no longer need the layer mask because the Lens Blur filter has finished using it, so choose Layer>Layer Mask>Delete and you’re done.
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This entry was posted on Thursday, November 8th, 2012 at 7:00 am and is filed under Tutorials. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a comment. Pinging is currently not allowed.