Archived posting to the Leica Users Group, 2008/11/25

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Subject: [Leica] CS4 Extended Depth of Field Trial
From: freakscene at weirdness.com (Marty Deveney)
Date: Tue Nov 25 17:24:12 2008

As Henning has pointed out this technique has advantages that simply 
stopping down does not always offer.  Also remember that people other than 
photographers use Photoshop.

Here at work we use Zeiss Extended Focus http://tinyurl.com/65om5t to make 
extended depth of field (DoF) images from microscopy.  Microscopes do not 
have apertures so you can't stop down and at high magnification DoF is very 
shallow.  Extended Focus controls the motorised column on our Zeiss 
microscopes, takes a series of images and combines them, including 
compensating for shifts in the image stack caused by the different 
perspective when using a stereo (dissecting) microscope.

Other advantages of using stacked images include improved management of 
diffraction (which often degrades macro or micro photos) and smoother tonal 
transitions because of the larger number of pixels used to generate the 
final image, but the main one os total control of depth-of field, which you 
don't get when stopping down because you can generally only control it 
within optically defined limits.

Marty

Gallery: http://gallery.leica-users.org/v/freakscene


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