NATURA

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This is just a brief description of a few animals
that can be found in the city of Nottingham,
but of course many more species can be seen.
The awareness of the value of urban wildlife is
increasing. Research have shown that it does
matter for people to have a window with a
view over natural environments. Patients tend
to recover sooner than if they only see concrete
from their window.
Through time, humans have tried to attract
wildlife into urban environments by feeding
or changing the environment to make
it more suitable, e.g. by putting up nest
boxes for birds and by planting. Cities are
designed with green areas and the public
opinion is that access to wildlife is of great
value for everyone.
Image 20. Sculpture of “The Green Man” made by
Stan Bullard. Resembling the theme, man’s interaction
with the natural green world.
Focus stacking is a technique in digital image processing
where two or more images are layered together to make one
image with increased depth of field. To use this technique, a
series of images must be taken at different depths. It depends
on the aperture how many focus points are needed to get the
depth of field required. The wider the aperture (smaller F),
the more images are needed.
The best way to take the images is to have the camera in a
locked position, either on a tripod or by using Macro focusing
rail (hand hold is almost impossible). By focusing the
camera manually with different focus areas, or by focusing
automatically moving the focus point for each image, and
then laying them all together having the computer screening
out the focus areas, the depth of field can be increased.
This process to screen out the focus areas can be done with
software such as Photoshop, Helicon and Zerene Stacker.
They all follow the same basics.
When using Photoshop, the first step is to open all the images
and then choose File - Automate - Photomerge. A window
will open with a few different processes. The best way is to
select Auto and then deselect Blend images together. The
next step is to select Add open files and then the open images
will appear in the box. Click OK, wait a few seconds and give
the program time to process. A new image will appear with
the title Untitled panorama, and with layers as many as the
original images. Select all the layers and click - Edit - Auto
Blend layers and another dialogue box will open. Make sure
to select Stack images and press Ok. Photoshop will then
select the sharpest area of each image and mask of the rest.
This should result in a sharp image with a great depth of
field.
When is focus stacking used?
It is useful in macro photography where it is frequently used.
For biologists, this method is important when taking images
in a microscope or a stereoscope where time, ISO, light and
magnification are the only things possible to control.
Focus stacking is used in landscape photography when the
photographer is aiming for sharp large prints. It is also useful
when light is limited and long exposure cannot be used.
natura_____21