The Differences Between Professional Films and General Picture-Taking Films
THIS ARTICLE HAS BEEN COPIED WITH THE PERMISSION OF EASTMAN KODAK CO.
Kodak manufactures color negative films and color reversal films for
professional applications and general use. It is important to
understand the different characteristics of films with the
"professional" designation and those without it. These characteristics
are significant to professional photographers, photo hobbyists, and
All color films are composed of several layers of complex emulsions
made of different chemical compounds. Since these compounds tend to
change slowly with time, all color films will age, beginning on the day
they are manufactured. As films age, their color balance and other
characteristics may change slightly. To provide films that meet the
needs of different types of photographers, Kodak allows for this aging
process during manufacture.
Kodak builds a small manufacturing bias into general picture-taking
films to compensate for changes that usually occur during storage and
use. This bias allows for changes produced by room-temperature storage
and for typical delays between purchase and processing. For example, if
a given film shifts toward yellow-green as it ages, it will be
manufactured with the color balance shifted toward blue-magenta to
compensate. The color balance of this film would shift away from blue-
magenta during shipping and storage to provide a good color balance
over the normal period of use.
The professional photographer has more demanding requirements than the
general picture-taker has. The professional photographer needs to know
that a particular film is near its optimum color balance at the moment
it is put into the camera. He or she must also be able to measure,
through testing, any slight color or speed bias in a particular film or
emulsion, and then adjust filtration and exposure to compensate. Kodak
professional films are close to optimum color balance when they are
manufactured and packaged. The film will stay near this balance when
it is stored at 55 (13) or lower (under refrigeration)--until the
"Process Before" expiration date printed on the film carton.
Professional photographers tend to buy large quantities of film at one
time. To obtain the best quality and to save time and money,
professional photographers need to know that the color balance and
speed of all of this film has been accurately established, that the
film is consistent from roll to roll, and that it will not change
significantly during the time the stock is being used.
Professional color films are not kept in a camera for long periods.
Generally, a professional photographer will have the film processed
within hours or days after exposure so that the color balance doesn't
shift significantly. A photographer will often have film processed and
checked while holding expensive models or products and props on a set.
Professionals need to be sure that the film reproduces colors in a way
that meets their clients' needs.
Casual picture-takers, on the other hand, usually buy one or two rolls
of film at a time. One roll of film may remain in the camera
for several weeks or months before being processed. The nominal film
speeds of films intended for general picture-taking are provided on the
film carton and in the instructions. Because of the exposure latitude
of Kodak films and typical conditions of use, exposing the film at the
nominal film speed will produce good results for general picture-taking
Kodak professional color films can usually be identified by the word
professional in the name--for example, KODAK EKTACHROME 100
Professional Film. The names of other professional films for special
applications usually contain a word that indicates the intended use of
the films--for example, KODAK EKTACHROME Duplicating Film / 6121.
Only professional films are supplied in sheets, multiple-roll pro-packs, and
long rolls. General picture-taking films, commonly referred to as
"amateur" films, are sold as single rolls, and two or three rolls to a
package, depending on the film.
The slightly higher cost of professional films is due to the increased
cost of manufacturing them. This cost includes the testing involved in
providing products with differing aim points, additional formats, and
specific film-speed ratings (within 1/3 stop) for batches of some
films. For example, specific film-speed data, as well as reciprocity
information for sheet sizes of KODAK EKTACHROME Professional Films,
assist professional photographers doing critical work. Proper use of
the supplementary data minimizes the amount of testing and film usage
that would otherwise be required to establish the exposure conditions
for a high-quality professional photograph to meet the critical needs
of commercial clients.
Use all films before the expiration date printed on the film carton.
You will also obtain the best quality when the film is processed
promptly after exposure.
Storage Conditions for Kodak Color Films
Current KODAK Films (amateur and professional) are more stable than
past generations of films. However, all films are perishable products
with a typical pre-process life expectancy of 1 to 3 years.
General picture-taking films are designed for room-temperature storage;
professional films require refrigerated (55 degrees F [13 degrees C] or lower) storage.
Professional films are not significantly more perishable, but they
require refrigeration because they are manufactured so that they are
near their optimum color balance at the time of shipment. Refrigeration
reduces the effects of normal aging and provides minimum changes
throughout the life of professional films. Refrigerated storage will
insure minimum variability, but this does not preclude normal use on
extended assignments under reasonable ambient conditions. You should
protect all films from high temperatures and high relative humidity;
these conditions accelerate the changes associated with film aging.
In general, you can expect minimal changes in amateur color negative
films that are stored at 78 degrees F (25 degrees C) or lower during the first few
months. These changes become measurable after 3 to 9 months of
storage. However, since this is the normal time during which the
majority of film is used, these changes are anticipated and allowed for
during manufacture. Changes become more pronounced as the film
approaches its "Process Before" date (printed on the film carton), but
these changes can be compensated for during printing.
The degree of change is not significantly different for professional
color negative films. But because these films are near their optimum
color balance when they are shipped, combining the same rate of change
may result in undesirable effects in prints from film approaching its
expiration date if the film is stored at room temperature. These
changes also increase variability of results, which is unacceptable in
applications that require consistency.
You can expect small, gradual changes at normal ambient conditions.
These changes alone do not cause a significant loss of quality in
amateur or professional films. However, in professional applications,
this reduces the tolerance for other changes in the system that might
produce quality losses when combined with film changes.
Little or no change is observed in amateur color reversal films in the
first few months of room-temperature storage. You can observe changes
after 3 to 9 months, but these changes are anticipated and allowed for
during manufacture. Again, the changes become more apparent as the
film approaches its "Process Before" date. The most noticeable change
will be a slight shift in the overall color balance, but it will not be
enough to adversely affect the normal use of these films.
For professional reversal films under reasonable ambient conditions, no
significant change is noticeable in the first couple of months. Color
shifts may be noticeable in the 3- to 9-month range, especially when
films are critically examined on an illuminator. Greater color shifts
will become apparent as the film reaches its expiration date, but they
will be within a range that is readily corrected in any reproduction
(e.g., duplicating, photomechanical reproduction). However, since
editors and art directors may be influenced by moderate color shifts,
refrigerated storage of professional color reversal films takes on
increased importance. Avoiding color shifts is especially important
with reversal films because you cannot make corrections before judging
the final image as you can with color negative films. Refrigerated
storage assures maximum consistency and minimal change through the
Films intended for amateur use do not require refrigerated storage;
changes that may occur at normal room temperature are anticipated
during manufacture. While the rate of change is not significantly
different in professional color films, more critical requirements in
professional images, narrower tolerances for change, and the costs
associated with inconsistency in professional applications add to the
value of refrigeration for extended storage. This does not preclude
use on extended assignments (a few weeks to a couple of months) if you
avoid adverse conditions such as high temperature and high relative
humidity. A few specialty films intended for situations that prohibit
refrigerated storage are also available. These films, intended for
room-temperature storage, include KODAK EKTAPRESS GOLD Professional
Films (available in 5-roll pro-packs and 50-roll press-packs) and KODAK
EKTACHROME 64 Film and KODAK EKTACHROME 100 PLUS Film
These films are intended for photojournalists and other professional
photographers who use large amounts of film where refrigerated storage
is not possible.