KODAK Color Films: The Differences Between Professional Films and General Picture-Taking Films

Kodak manufactures color negative films and color reversal films forprofessional applications and general use. It is important tounderstand the different characteristics of films with the"professional" designation and those without it. These characteristicsare significant to professional photographers, photo hobbyists, andeveryday picture-takers.All color films are composed of several layers of complex emulsionsmade of different chemical compounds. Since these compounds tend tochange slowly with time, all color films will age, beginning on the daythey are manufactured. As films age, their color balance and othercharacteristics may change slightly. To provide films that meet theneeds of different types of photographers, Kodak allows for this agingprocess during manufacture.Kodak builds a small manufacturing bias into general picture-takingfilms to compensate for changes that usually occur during storage anduse. This bias allows for changes produced by room-temperature storageand for typical delays between purchase and processing. For example, ifa given film shifts toward yellow-green as it ages, it will bemanufactured with the color balance shifted toward blue-magenta tocompensate. The color balance of this film would shift away from blue-magenta during shipping and storage to provide a good color balanceover the normal period of use.The professional photographer has more demanding requirements than thegeneral picture-taker has. The professional photographer needs to knowthat a particular film is near its optimum color balance at the momentit 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 oremulsion, and then adjust filtration and exposure to compensate. Kodakprofessional films are close to optimum color balance when they aremanufactured and packaged. The film will stay near this balance whenit 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 onetime. To obtain the best quality and to save time and money,professional photographers need to know that the color balance andspeed of all of this film has been accurately established, that thefilm is consistent from roll to roll, and that it will not changesignificantly 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 processedwithin hours or days after exposure so that the color balance doesn'tshift significantly. A photographer will often have film processed andchecked while holding expensive models or products and props on a set.Professionals need to be sure that the film reproduces colors in a waythat meets their clients' needs.Casual picture-takers, on the other hand, usually buy one or two rollsof film at a time. One roll of film may remain in the camerafor several weeks or months before being processed. The nominal filmspeeds of films intended for general picture-taking are provided on thefilm carton and in the instructions. Because of the exposure latitudeof Kodak films and typical conditions of use, exposing the film at thenominal film speed will produce good results for general picture-takingsituations.Kodak professional color films can usually be identified by the wordprofessional in the name--for example, KODAK EKTACHROME 100Professional Film. The names of other professional films for specialapplications usually contain a word that indicates the intended use ofthe films--for example, KODAK EKTACHROME Duplicating Film / 6121. Only professional films are supplied in sheets, multiple-roll pro-packs, andlong rolls. General picture-taking films, commonly referred to as"amateur" films, are sold as single rolls, and two or three rolls to apackage, depending on the film.The slightly higher cost of professional films is due to the increasedcost of manufacturing them. This cost includes the testing involved inproviding products with differing aim points, additional formats, andspecific film-speed ratings (within 1/3 stop) for batches of somefilms. For example, specific film-speed data, as well as reciprocityinformation for sheet sizes of KODAK EKTACHROME Professional Films,assist professional photographers doing critical work. Proper use ofthe supplementary data minimizes the amount of testing and film usagethat would otherwise be required to establish the exposure conditionsfor a high-quality professional photograph to meet the critical needsof 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 processedpromptly after exposure.Storage Conditions for Kodak Color FilmsCurrent KODAK Films (amateur and professional) are more stable thanpast generations of films. However, all films are perishable productswith 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 theyrequire refrigeration because they are manufactured so that they arenear their optimum color balance at the time of shipment. Refrigerationreduces the effects of normal aging and provides minimum changesthroughout the life of professional films. Refrigerated storage willinsure minimum variability, but this does not preclude normal use onextended assignments under reasonable ambient conditions. You shouldprotect 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 negativefilms that are stored at 78 degrees F (25 degrees C) or lower during the first fewmonths. These changes become measurable after 3 to 9 months ofstorage. However, since this is the normal time during which themajority of film is used, these changes are anticipated and allowed forduring manufacture. Changes become more pronounced as the filmapproaches its "Process Before" date (printed on the film carton), butthese changes can be compensated for during printing.The degree of change is not significantly different for professionalcolor negative films. But because these films are near their optimumcolor balance when they are shipped, combining the same rate of changemay result in undesirable effects in prints from film approaching itsexpiration date if the film is stored at room temperature. Thesechanges also increase variability of results, which is unacceptable inapplications that require consistency.You can expect small, gradual changes at normal ambient conditions.These changes alone do not cause a significant loss of quality inamateur or professional films. However, in professional applications,this reduces the tolerance for other changes in the system that mightproduce quality losses when combined with film changes.Little or no change is observed in amateur color reversal films in thefirst few months of room-temperature storage. You can observe changesafter 3 to 9 months, but these changes are anticipated and allowed forduring manufacture. Again, the changes become more apparent as thefilm approaches its "Process Before" date. The most noticeable changewill be a slight shift in the overall color balance, but it will not beenough to adversely affect the normal use of these films.For professional reversal films under reasonable ambient conditions, nosignificant change is noticeable in the first couple of months. Colorshifts may be noticeable in the 3- to 9-month range, especially whenfilms are critically examined on an illuminator. Greater color shiftswill become apparent as the film reaches its expiration date, but theywill be within a range that is readily corrected in any reproduction(e.g., duplicating, photomechanical reproduction). However, sinceeditors and art directors may be influenced by moderate color shifts,refrigerated storage of professional color reversal films takes onincreased importance. Avoiding color shifts is especially importantwith reversal films because you cannot make corrections before judgingthe final image as you can with color negative films. Refrigeratedstorage assures maximum consistency and minimal change through theexpiration date.Films intended for amateur use do not require refrigerated storage;changes that may occur at normal room temperature are anticipatedduring manufacture. While the rate of change is not significantlydifferent in professional color films, more critical requirements inprofessional images, narrower tolerances for change, and the costsassociated with inconsistency in professional applications add to thevalue of refrigeration for extended storage. This does not precludeuse on extended assignments (a few weeks to a couple of months) if youavoid adverse conditions such as high temperature and high relativehumidity. A few specialty films intended for situations that prohibitrefrigerated storage are also available. These films, intended forroom-temperature storage, include KODAK EKTAPRESS GOLD ProfessionalFilms (available in 5-roll pro-packs and 50-roll press-packs) and KODAKEKTACHROME 64 Film and KODAK EKTACHROME 100 PLUS Film (in Press-Pacs).These films are intended for photojournalists and other professionalphotographers who use large amounts of film where refrigerated storageis not possible.