AV News 187 - February 2012
It is however ideal for high contrast images containing no movement such as
internal and external architecture and some landscapes or cityscapes under
difficult lighting conditions. Apart from exposures we need to keep everything
as constant as possible. To avoid any change in the recorded depth of field use
manual settings and retain the chosen aperture by varying camera shutter
speed for each of the three exposures, or choose aperture priority if using your
camera's automatic facility to enable the camera to change shutter speeds. To
avoid your camera re-focusing between shots its advantageous to turn off its
automatic focus after composing and preparing for the first exposure.
So far everything is just basic
good photographic practice. Now
that you have your images you
need to load them into Photoshop
onto
three
separate
layers.
Depending on which version of
Photoshop you own this could be
achieved simply and in one
operation by opening the 'Files'
menu, choose 'Scripts' then 'load
files into Stack' then simply select
the appropriate files and click OK..
However if your older version of
Photoshop does not support
'stacking' then simply open each
image file in turn and drag into
Photoshop to create one file with
three layers.
Place the darkest layer as your top layer, this will be your under exposed
image. Place your normally exposed image as the centre layer, and your over
exposed image as the bottom layer. For many photographers their first step
after opening an image is to make adjustments using 'levels' please don't.
Because you are going to use only the appropriate parts of each image you will
finally generate one picture containing the full tonal range derived from each of
the three separate exposures, the use of levels at this stage could impair this
process or its required result.
Ensure that your top (darkest) layer is highlighted and thereby selected, now
choose the 'Eraser Tool'. Adjust the eraser tool to about 10% 'Flow' and the
brush to about 50% softness, adjust the brush size to meet the requirements
of your particular image. Gently brush away the underexposed dense areas
leaving only the important highlight areas of this layer.
If you find this a bit daunting and concerned about removing the wrong areas
you may find it useful to select the highlight areas then inverse your selection,
then add a small amount of feathering to the selection. Now when you erase
you will not damage the highlight areas by accident. In our example of the
church interior this would leave the bright windows and stained glass
untouched (see the underexposed thumbnail in the above image).
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