I try to know if there is a coral filter which make the same
mired shift made by a regular 85 filter. I was told that is
the coral #5, but I would like another opinion. Is it #5 from
Tiffen or another brand?
For each strength from the coral filters, is there a given
Please help me with this little problem. I can't actually
verify this with a color temperature meter and the filters,
for the moment.
That's why I am asking you.
The Tiffen Coral filters and the Schneider Coral filters are
color effect filters and are not graded for color correction.
The original Harrison and Harrison Coral filters are correction
filters and a "#5" Harrison is often considered
the equivalent of an 85. The mired shift of a Coral #5 is
actually 150 points and a #4 is 130 points. There is also
a Harrison blue series for correction and both correlate directly
to mired shifts.
Tiffen makes what are called Decamired Filters, which are
graded and numbered according to their color and decamired
shift, ie. R1.5, R3, R6, R12, B1.5, B3, B6, B12. In this system
the R12 is equivalent to a +120 mired shift.
The visual color of our Coral 5 comes closest to that of the
85B; our Coral 3 is closest in appearance to the density of
the 85. In both cases, though, the actual mired shifts of
the Corals are somewhat greater than the equivalent visual
values would indicate. The Coral 3 is almost the same mired
shift as the 85B; the Coral 2 is very close to the 85.
The differences in color vs. mired shift relate to the fact
that our Corals were not designed to have the same spectral
distribution as the 85- they were to allow for a varied range
of densities that closely followed the visual differences
in sunlight throughout the day.
The Tiffen Company
Hauppauge, NY 11788
A History of the Coral and Blue Light Corrector Discs
In 1938 the coral, or coralite and blue, or bluelite filters
as they were called then, were developed by Harrison in conjunction
with the Harrison visual color meter to compensate for the
different colors of light such as daylight, late afternoon,
photoflood, tungsten, etc., used in color photography.
To arrive at the steps of coral density, a long coral wedge
was made with mechanical marks on the edge like a ruler so
that by sliding the wedge in front of a camera and taking
pictures in short intervals, the pictures that showed a color
difference was considered a step and this density of color
measured to make a filter number - originally from C-1 to
C-8. The color filters compensated for excess blue from the
film balance and the blue filters compensated for an excess
of red from the film balance according to arbitrary readings
on a visual color meter.
Later when the series was calibrated in degrees Kelvin, and
correlated to a visual color temperature meter - reading in
both degrees Kelvin and the filter number, the series was
extended to from C-1/8 to C-14.
Since they have been the most complete range of color temperature
filters available, over the years they have been used in combination
with many different color temperature meters for color temperature
Recently however, with the advent of giving pictures a warm
or old time look, they have been used for that purpose since
the range of the same color enables the same warming effects
on different color balance films.
For example : a tungsten 3200K balanced film with 3200K light
would only need the light C-1/2 to C-4 range to warm up the
picture - whereas the same film on exteriors would need a
C-6 to C-9 to add the same amount of color as the C-5 would
be needed to match the film to daylight. The only way the
same amount of color can be added consistently therefore,
is to measure the color temperature of the light for film
balance, as a light; bluer than the film balance, a 3200K
film in daylight for example, can offset several steps of
coral just to balance the film and not add any warming effect
The Harrison light corrector disc chart shows the light balance
for each film in degrees Kelvin and what filters to use if
it is not in balance.
With the light balanced for the film being used, the coral
filters will add the same amount of color each time - and
this amount is up to the judgment of the photographer, as
it is an artistic amount rather than a scientific amount -
the C-1/2 to C-5 being a medium color range for films that
are light balanced, and the C-6 to C-9 for special heavy effects,
or to color balance the film and then add color.
Harrison & Harrison Optical Engineers, Inc.
I once worked with a Cameraman many years ago, (geez I find
myself saying that more and more lately,) who would decide
upon a color temperature he wanted to work at. 2800 or 4200
or whatever effect he wanted to produce. He had a huge assortment
of Coral and CC Blue filters.
For exterior work, he then would take his color temp meter
and apply the appropriate filters to achieve the desired temp.
As the sun changed throughout the day, he would adjust the
filters to maintain the consistent Kelvin temp. Pretty ingenious,
but lugging around the hundreds of filters got to be a bit
of a pain (literally).