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Tuesday, November 6, 2012

Extended Depth Of Field

Focus stacking defeats the limits of optics

This Article Features Photo Zoom

5) Helicon Focus' main window

If this method fails (sometimes it does, unpredictably), try this route:

1. Select the exposures to merge—File > Scripts > Load Files Into Stacks, checking Attempt to Automatically Align Source Images.
2. In the Layers palette, highlight the separate layers by Shift- or Command-clicking them.
3. Go to the Edit menu and select Auto-Blend Layers.
4. Photoshop automatically will mask the layers to reveal the sharpest image areas.

You then can further refine these results, including manually adjusting the automated masks or distorting layers, but this is rarely necessary. Photoshop does a fine job for a majority of applications.

When you're looking for the highest quality, consider focus stacking with Helicon Soft's software, Helicon Focus. It delivers superior sharpness consistently and can be used to batch-process multiple focus-bracketed sequences. Take these steps:

1. Click the Add Images icon; select the exposures to be combined.
2. Click the Render button to save a combined result.
3. Option: Choose a Method other than the default Method B (Depth Map)—Method A (Weighted Average) or Method C (Pyramid).
4. Option: Use the Radius slider; this helps refine the software's search for focused sources by specifying a line width to favor.
5. Option: Use the Smoothing slider; lower settings generate sharper results, while higher settings create smoother transitions between sources.
6. Option: Use the Autoadjustment dialog to refine image alignment.

6) Helicon Focus' Autoadjustment panel

Why not just selectively sharpen images to achieve similar effects? Digital sharpening skills aren't a substitute for focusing skills, rather they're an enhancement to them. Optical sharpness is superior in quality to digital enhancement—plus, it's more flexible. You'll be able to achieve superior digital sharpening results with better focused image sources. After all, no amount of digital sharpening wizardry will make truly out-of-focus images appear to be in focus—yet. In the not-too-distant future, focus stacking will be performed automatically in-camera during exposure, and depth of field will be controlled by sliders during postprocessing. Today, it still pays to know how to focus. You can go way beyond autofocus with focus stacking. You can surpass the limits of traditional tools and techniques with these new practices. Focus stacking works more like our eyes and mind work together in concert with one another than the camera eye does on its own. In fact, you can do what's impossible to do with either eye or lens at one moment in time, like focus two parallel planes at significantly different distances.

You can get highly technical with this technique, but I recommend keeping it as simple and practical as possible—so that you'll use it more frequently. Develop this new habit, and you'll quickly find many situations where focus stacking will help you make images of superior technical quality, sometimes subtly superior and other times dramatically superior.

Visit this url to read more on depth of field: www.johnpaulcaponigro.com/downloads/technique/exposure.php.

John Paul Caponigro, author of Adobe Photoshop Master Class and the DVD series R/Evolution, is an internationally renowned fine artist, an authority on digital printing, and a respected lecturer and workshop leader. Get his enews Insights with access to hundreds of lessons at www.johnpaulcaponigro.com.