February 2008
John McCormack
Oriental poppy – Papaver orientalis ‘Viva’ a botanical close up photograph taken in the National poppy collection at Sandy Worth’s nursery near Winchester.This photograph has used multi image photography to create a greatly increased depth of field, impossible to achieve with single image photography. It also has an enhanced definition showing details such as individual pollen grains.
This photograph is not one single picture, but 47 images merged to produce a combination ‘stack’.
f 8 was used to obtain the optimum lens resolution. Closing the aperture down to say f32 (which is usually the normal procedure for macro images) introduces a physical distortion known as diffraction which disfigures the final image. This distortion is usually not seen in small magnitude enlargements, but is especially seen in large prints. This is one of the very reasons why you normally do not see large size sharp prints of close up and macro subjects!
Here the exposures are only 0.5mm apart using a Nikon D2X and a 105 macro lens on a Manfrotto slide macro focusing jig. This is the only successful image I have ever taken using natural light for this method of close up botanical photography. Normally I now use the Nikon macro flash system with three flash heads to control the lighting. I was lucky with constant natural lighting on that particular day. It took about an hour to take the successional photographs.
All these images were then merged, using ‘Helicon Focus’ software. This uses edge detection algorithms to select the ‘in’ focus part of each picture. Then each resultant image is selected and merged to its adjacent frame. Remapping of each image in the stack is carried out to produce a final sharp picture. Stunningly sharp images A3+ size prints can be obtained to a standard quite unthinkable by any other standard method.
jandmmccormack@ntlworld.com
Date submitted:11/02/08 16:34
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