The
weather has been great this past week and
not one to pass up such a rare opportunity I have moved my office to the end of
the garden where it is shaded by some
silver birch trees. If it was not for the shade I would not be able to see the
computer screen.
As you know
from previous posts I have become quite smitten with my Zero 6x9 deluxe camera.
It's lack of through the lens metering! Your right no lens, I have had to
revert to using a hand held one. NO! I'm not going to take another camera with
TTL with me. Why load myself down, believe it or not even with a tripod it is
lighter than my standard kit. Besides I don't need the light readings to be
that spot on especially when needing to account for reciprocity.
While
writing this I'm joined by a baby starling. It looks like the one I saved from
the jaws of the cat the other day. The bird seems happy for me to be here as
he/she walks up to and around the chair I'm sitting in looking for local
delicacies. It appears I'm the last thing it needs to worry about.
 |
| Two types of hand held light meter |
I have two
types of meter to choose from they are tried and trusted run of the mill units.
The oldest one uses a selenium cell which is a type of photovoltaic / solar
cell. When the front of the meter is exposed to the light it produces a small
current which moves a needle that indicates how much light there is. This type
of meter is batteryless but one of the down sides is in low light situation it
requires a certain light level to read accurately.
The other
light meter is a CdS unit or Cadmium Sulfide cell that has a greater low light
sensitivity. This light meter works by regulating the energy in the battery
rather than producing a current as in the former. With this type of meter it
can suffer from drifting this is where the meter has been shown a bright light
temporarily making it blind. The cell has a memory and can fool you into
thinking the level of light has not changed. It is a good idea to let the meter
read the scene for several seconds to make sure it has read it properly.
 |
Note the starling casting a
critical eye over the
photographs. |
Todays
meters do not suffer from this they use silicon blue or gallium arsenide
photocell coupled to a memory chip so
are unlikely to have a time lag in changing light conditions.
My light
meters are general purpose, they read reflective light from a fairly large area
of the subject which is about 30 degrees. They round this reading to an average
of 18% ( a mid grey) no matter how dark or bright the scene is. This is where
the zone system ( See Ansel Adams The Negative for more info) comes into its
own or a system of your own to allow for it. I have my own method that works
well with a little bit of intuition thrown in. Well! Most of the time.
Since writing this my CdS light meter has passed away. It will be missed.
