The histogram- description
A histogram is a graphic representation of showing the
distribution of highlights ( white) and shadows ( black).
The histogram represents the dynamic range recordable
by the camera.diagram of f stop brackets against
18% grey tones.
luminous-landscapes.com
The ideal when shooting an image is to ensure that you
capture both areas of light and dark and for the histogram
to be weighted as a curve in the mid range of tones. This means
that all details of the image have been captured. Artistically you
may want to shoot a low contrast or high contrast image which
means that the curve will be weighted towards dark tones
or light tones.It is important that there is not detail is not lost
in the dark tones and for high contrast images the highlights
are not "burnt" out.
Below is a sequence showing the change in Dynamic range
on the histogram based on the different lighting conditions.
LOW CONTRAST
this image of a white cup on white back ground shows
limited contrast. The histogram is not flat but this mid tone
image shows the histogram in the middle of the dynamic
range
f10 /60 sec
The next image shows exposure two stops under
and the histogram has moved from the middle to
the dark end of the dynamic scale.
f14 1/60 sec
the image below shows the exposure at 2 stops over
the range has now moved into the light area.
f 6.3 1/60 sec
artistically i would process the image over exposed
as it is more appropriate for the subject matter.
HIGH CONTRAST
This image shows the variance between light and dark
the below image shows the average exposure so
the histogram is flat. The spike is the black background
and is causing the large reading in the dark
area of the histogram.
f 60 1/10 sec ave exposure
the below images shows the exposure at 2 stops over
exposed at f 6.3 the curve has moved into the light
area of the dynamic range. The black spike
still exists but has moved closer to the middle
of the dynamic range.
f6.3 1/60 sec
The final image shows the exposure at 2 stops under
exposed at f14.
The curve is now in the dark area of the dynamic range.
f 14 1/60 sec
The histogram suggests to me that this image should be
processed in layers as the black background needs
to be dark to not show detail such as image 3 and the
cup needs to be exposed correctly an appear white
such as in image 2.
NEUTRAL CONTRAST
The below image shows neutral contrast between the
back ground and the object. The average exposure
of f10 shows a flat curve which spreads across
the dynamic range of light and dark. The spike
in light area denotes the white background
f10 1/60 sec
the below image shows the tonal range at 2 stops under
the average exposure. The large spike which is the
backdrop is now in the dark range. The flat curve
of the pot in now showing a steep curve as the black
tones of the pot are now very black
f14 1/60 sec
this image is two stops over exposed and you
can see a spike into the outer limit of the dynamic
range. This is showing that there is areas of detail
missing in the highlights as the backdrop is now
over exposed.
f6.3 1/60 sec
I would process from the average exposed image
which shows that the image has captured all tones
from light to dark, which would allow for greater
depth to reprocess in photoshop.
LESSONS LEARNT.
It is important to capture the image at an exposure
level that captures both areas of light and dark.
I will continue to shoot with the histogram visible
on the camera's screen so I can assess the exposure
level not just as a visible view but now I can read the
data and ensure that I have a good tonal range
which will allow greater ability to re process in
photoshop.
No comments:
Post a Comment
Note: only a member of this blog may post a comment.