Ektachrome Commercial Type 7255
Subtractive 3 color: Chromogenic monopack, 16mm reversal
Original Technical Papers and Primary Sources
Groet, N.H.; Liberman, M.; Richey, F. (1959): An Improved Professional 16mm Reversal Camera Film. In: Journal of the Society of Motion Picture and Television Engineers, 68, January 1959, pp. 8–10.
Keene, G. T.; Clifford, J. D. (1962): Commercial Systems for Making 8mm Prints. In: Journal of the Society of Motion Picture and Television Engineers, 71,6, pp. 447–449.
Anonymous (1961): What is Color Correction? In: American Cinematographer, 42,2, Feb. 1961, p. 104 and p. 108.
Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 167-179.
Vittum, P. W. (1962): Chemistry and Color Photography. In: Journal of the Society of Motion Picture and Television Engineers, 71,12, pp. 937–941, on p. 940.
“In 1958 Ektachrome Commercial Film, Type 7255, was introduced as a 16 mm camera film for the professional worker. This film is a multilayered subtractive three-color film intended as an improved replacement for Kodachrome Commercial Safety Color Film, Type 5268.26 ECO is balanced for exposure to a tungsten light source with a color temperature of 3200°K. Its exposure index with this type of illumination is 25. For daylight exposure ECO has an exposure index of 16 when used with a Wratten 85 Filter.
Structurally ECO is similar to its predecessor KCO, consisting of three light sensitive emulsions coated one on top of the other on a single film base (Fig. 55). The emulsion nearest the base is sensitive to red light and blue light, the middle emulsion is sensitive to green light and blue light and the top emulsion is sensitive to blue light. Between the top blue sensitive emulsion and the other two emulsions is a layer of gelatin containing finely divided silver particles called a “Carey Lea layer.” These silver particles absorb blue light and act as a filter that prevents blue light exposure of the middle and bottom emulsion layers. The chief structural difference between ECO and its predecessor is that the color forming couplers are incorporated in the Ektachrome emulsions. The red sensitive emulsion layer contains a cyan dye-forming coupler, the green sensitive emulsion layer contains a magenta dye-forming coupler, and the blue sensitive emulsion layer contains a yellow dye-forming coupler.
After exposure Ektachrome Commercial is developed in an Elon Hydroquinone black and white developer to produce a negative silver image. This is followed by wash to remove the excess developer then the film is hardened in a chrome alum hardener which serves as a combination hardener and stop bath. To prevent sludging in the wash after the hardener, the film first passes into an acid rinse which maintains its low pH. This is followed by a normal wash and the reversal exposure. The reversal exposure is made with white light, and can be either from the emulsion side or the base side, or both as long as it is sufficient to expose all the remaining silver halide in each of the three light sensitive layers. The white light exposure is followed by development in the color developer. During development the oxidized developing agent in the developer couples with the dye forming couplers located in each emulsion layer forming a positive dye image along with the positive silver images. The excess color developer is removed by a wash followed by a second hardening in a chrome alum hardener. After hardening the film passes into another acid rinse and wash; then the metallic silver image is converted to silver halide by immersion in aferricyanide bleach and removed in the fixing bath. A final wash is followed by a stabilizing bath; then the film is dried.27
Prints can be made in several different ways.
1. Direct reversal color prints by contact or optical printing onto Ektachrome Reversal Print Film, Type 7386.
2. Direct reversal color prints by contact or optical printing onto Eastman Reversal Color Print Film, Type 7387.
3. Direct reversal black and white prints by contact or optical printing onto Eastman Reversal Duplicating Film, Type 7361.
4. Color prints on Eastman Color Print Film, Type 7585, made by first printing an internegative on Eastman Color Internegative Film, Type 7270.
5. Color prints on either of the films listed in the first two methods using 7255, 7386, or 7387 as a reversal color master positive.
6. Black and white prints on Eastman Fine Grain Release Positive Film, Type 7302 or Type 7303, made by first printing a duplicate negative on Eastman Fine Grain Panchromatic Duplicating Negative Film, Type 7234.
7. 35 mm color or black and white prints can be made by enlargement to the 35 mm equivalents of the film listed above in methods 1, 4 and 6.
8. 35 mm or 16 mm Technicolor imbibition prints were also made printing three separation negatives from the Ektachrome and from these separations preparing three matrices.
The following is the processing cycle and formulas for processing Ektachrome Commercial Film, Type 7255, in process ECO-1.30
Ektachrome Commercial Film, Type 725528
A low contrast reversal color camera film balanced for use under tungsten illumination of 3200°K. Its speed under this type of illumination is E.I. 25. For daylight exposure ECO has an exposure index of 16 with a Wratten 85 Filter.
Ektachrome Commercial Film, Type 725229
A low contrast reversal color camera film balanced for use under tungsten illumination of 3200°K. Introduced in 1969 this film was intended as a replacement for Ektachrome Commercial Film Type 7255 having the same speed E.I. 25 under tungsten illumination and E.I. 16 under daylight illumination with a Wratten 85 Filter. Its improved characteristics included better sharpness, increased latitude and greater process stability. The new process recommended for this film was ECO-3. It had the same chemical and mechanical specifications as the ME-4 process with the exception of the first developer and the backing removal step.
After the ECO-1 process had been in commercial use for approximately four years, a new improved process, ECO-2, was introduced. This new process operated at a higher temperature and featured a greatly reduced processing time and a cleaner process. A prehardener was introduced and the chrome alum hardeners were eliminated.
The following are the processing cycle and formulas for processing Ektachrome Commercial Film, Type 7255, in process ECO-2.31
In May 1960 two new reversal color films for use by the professional cinematographer and a new reversal color print film for laboratory use were introduced by the Eastman Kodak Company.32 These films, designated by the manufacturer as Ektachrome ER (Daylight) Types 5257 (35 mm) and 7257 (16 mm), Ektachrome ER (Type B), Types 5258 (35 mm) and 7258 (16 mm), and Ektachrome Reversal Print Film, Types 5386 (35 mm) and 7386 (16 mm), were three-color multilayered subtractive color films having incorporated color forming couplers.
The camera films in this group were designed for use under difficult lighting conditions where a high film speed is necessary. The print film was designed for processing in the same solutions as the camera films so that prints could be quickly made for editing and limited release.
The daylight balanced 5257 and 7257 have been used chiefly for instrumentation and data-gathering photography. Its high film speed permits the use of high-speed cameras and/or long focal length lenses. The tungsten balanced 5258 and 7258 have been used for in-plant photography, nighttime sporting events, color newsreel work and dramatic shows. The first use of Ektachrome ER to photograph a complete dramatic show was the one-hour Kraft Suspense Theater presentation “Once Upon a Savage Night.”34 This story was photographed in the Chicago area at night with existing light using 35 mm Ektachrome ER (Type B), Type 5258. From this reversal original an internegative was made on Eastman Color Internegative Film, Type 5270, and prints were made in the normal manner on Eastman Color Print Film, Type 5385. While the show received considerable attention from the entertainment industry, it did not create a trend. The use of Ektachrome ER continued to be limited to the photographing of single difficult scenes for productions in which the normal scenes were photographed with conventional color films.
Structurally these films were like Ektachrome Commercial Film, Type 7255 (Fig. 55), having the same layer arrangement and producing similar color reproduction. The general properties of the camera films were as follows:34
Eastman Ektachrome ER Film (Daylight Type), Types 5257 (35 mm) and 7257 (16 mm)
A high-speed reversal color camera film balanced for use under average daylight conditions. The speed of this film is E.I. 160. Introduced in 1960 as a regular product, this film was previously available on special order as Eastman Color Reversal Film, Daylight Type, SO-260 (35 mm and 16 mm).
Eastman Ektachrome ER Film (Type B), Types 5258 (35 mm) and 7258 (16 mm)
A high-speed reversal color camera film balanced for use under tungsten illumination of 3200°K. The speed of this film is E.I. 125. Introduced in 1960 as a regular product, this film was previously available on special order as Eastman Color Reversal Film, Type B, SO-270 (35 mm and 16 mm).
The general properties of the print film were as follows:35
Eastman Reversal Print Film, Types 5386 (35 mm) and 7386 (16 mm)
A reversal color print film balanced for printing by tungsten quality illumination having a color temperature of 2900°K, with appropriate balancing filters in the light beam.
Like the film structure, the processing steps and solutions are also similar to those used for Ektachrome Commercial Film; differences are in the two developers and in the solution times and temperatures. The similarity between the Ektachrome Commercial process ECOI and the Ektachrome ER process ME-2A is such that the same processing machine can be used for both processes. To accomplish this it is necessary to have auxiliary storage tanks and suitable pumping arrangements so that one set of solutions can be held in the storage tanks while the other set of solutions is in use. If such an arrangement is used the times required in the various solutions permit operation of the ECO-1 process at 50 feet per minute at 80° and the ME-2A process at 30 feet per minute at 75°F It is not desirable to operate the ECO-1 process at 75°F at the same processing machine speed as the ME-2A process, because this would result in a loss of effective emulsion speed of the Ektachrome Commercial Film. It is also not desirable to operate the ME-2A process at 80°F because of the danger of reticulation of the Ektachrome ER Films.
The table on page 175 lists a comparison of the required times and temperatures for the use of a single machine for processes ECO-1 and ME-2A.36
Approximately four years after the introduction of the Ektachrome ER and the ME-2A process, a new medium speed reversal color camera film was added to the group. This film, called Eastman Ektachrome MS Film, Types 5256 (35 mm) and 7256 (16 mm), had structural characteristics similar to those of the Ektachrome ER films and was also processed in the same ME-2A process.
The general properties of this third camera film were as follows:37
Eastman Ektachrome MS Film, Types 5256 (35 mm) and 7256 (16 mm)
A medium speed reversal color camera film balanced for use under average daylight conditions. The speed of this film is E.I. 64. Introduced in 1963, the improved characteristics exhibited by this film are lower graininess, better color reproduction and improved sharpness when compared with the Ektachrome ER film.
Concurrently with the introduction of the ECO-2 process in July 1964, a corresponding new color process for the higher speed Ektachrome films38 was also introduced. This process, designated ME-4, was recommended for the processing of:
Eastman Ektachrome ER Film (Daylight), Types 5257 and 7257
Eastman Ektachrome ER Film (Type B), Types 5258 and 7258
Eastman Ektachrome MS, Types 5256 and 7256
Eastman Reversal Print Film, Types 5386 and 7386
The relationship between the ME-4 process and the ECO-2 process is similar to that which existed between the ME-2A process and the ECO-1 process. All solutions, with the exception of prehardener, first developer and color developer, are common to both processes. The solutions have been adjusted so that at given developing machine speed the times in solution are the same for both processes.
The following are the processing cycle and formulas for the Ektachrome ME-4 process.
In November 1965 the Eastman Kodak Company announced that “recent advances in emulsion technology have made it possible to produce two new high-speed color reversal films.” These new films, designated Ektachrome EF, represent improvements in practically all the important characteristics by which films are judged. It is significant that these improvements were accomplished without a change in the processing solutions or processing steps, provided that the laboratory had already changed from the ME-2A process to the ME-4 process.39
The general properties of these camera films were as follows:
Eastman Ektachrome EF Film (Daylight Type), Types 5241 (35 mm) and 7241 (16 mm)
A high-speed reversal color camera film balanced for use under average daylight conditions. The speed of this film is E.I. 160. Introduced in 1965, this film replaced Eastman Ektachrome ER, Types 5257 and 7257. Its improved characteristics include finer grain, better sharpness and better color reproduction.
Eastman Ektachrome EF Film (Type B) Types 5240 (35 mm) and 7242 (16 mm)
A reversal color camera film balanced for use under tungsten illumination of 3200°K. The speed of this film is E.I. 125, Introduced in 1965, this film replaced Eastman Ektachrome ER Film, Types 5258 and 7258. Its improved characteristics include finer grain, better sharpness and better color reproductions.
Since its introduction Ektachrome EF, Type 7242, has been extremely popular for use as a television news film. This film’s ease of handling for both the photographer and the processor has resulted in several television stations installing their own color newsreel processing facilities.40
Parallel with the development of improved camera films that could be processed in the Ektachrome process a series of reversal color print films also evolved.
Eastman Ektachrome R — Print Film 738841
A low contrast reversal color print film designed for use in making direct prints from projection contrast original films. This film was balanced for filtered tungsten illumination of approximately 2900°K, Introduced in 1966 this film was designed to fill the need for a low contrast print film which could be processed in the ME-4 process. The sound track on 7388 was silver sulfide produced in the same manner and using the same formula that was used to produce a sound track on 7386 print film.
Eastman Ektachrome R — Print Film 738942
A low contrast reversal color print film designed for use in making direct prints from projection contrast original films. This film was balanced for filtered tungsten illumination of approximately 2900°K. Its improved characteristics included the capability to produce a silver optical sound track increasing sound quality considerably. Introduced in 1969 this film replaced Eastman Ektachrome R Print Film 7388.
Eastman Ektachrome Print Film 739043
A reversal color print film designed for use in making projection contrast prints from lower contrast reversal originals such as Ektachrome Commercial Film 7255 or 7452. This film was balanced for filtered tungsten illumination of approximately 2900°K. In a modified ME- 4 process (reduced 1st developer time) it can be processed to yield a silver optical sound track or a silver sulfide sound track. Introduced in 1971 this film replaced Eastman Reversal Print Film 7386.
27 Groet, N. H., Liberman, M. and Richey, F.,”An Improved Professional 16 mm Reversal Camera Film,” Journal of the Society of Motion Picture and Television Engineers, January, 1959, pp. 8—10.
28 Groet, N. H., et al, “An Improved Professional 16mm Reversal Camera Film,” loc. cit., pp. 8-10.
29 Grigsby, P. H., Kent, F., McDonough, J. M., Miller, D. R. Wolf, W. L., “A New Eastman Ektachrome Commercial Film.” Presented at 106th Technical Conference of the Society of Motion Picture and Television Engineers, Los Angeles, Sept. 1969.
30 Abridged Specifications for Processing Ektachrome Commercial Film, Type 7255 (Process ECO-1) (Motion Picture Film Department, Eastman Kodak Company, New York).
31Abridged Specifications for Processing Ektachrome Commercial Film, Type 7255 (Process ECO-2) (Motion Picture Film Department, Eastman Kodak Company, New York).
32 Groet, N. H., Murray, T. J. and Osborne, C. E., “Two High-Speed Color Films and a Reversal Print Film for Motion Picture Use,” Journal of the Society of Motion Picture and Television Engineers, November, 1960, pp. 813-817.
33 “Eastman Videbuts Ektachrome on NBC-TV’s ‘Suspense Theater’,” , Daily Variety, (Hollywood), March 2, 1964, p. 4.
34 Groet, N. H., et al, “Two High-Speed Color Films and a Reversal Print Film for Motion Picture Use,” loc. cit., p. 816.
35 Ibid., p. 817.
36 “The Use of a Single Machine for Processing of Ektachrome Commercial Film, Type 7255, and Ektachrome ER Film, Types 7257 and 7258” (Motion Picture Film Department, Eastman Kodak Company, February, 1960), Table 1.
37 “MS for Medium Speed,” Kodak Tech Bits, Eastman Kodak Company, No. 3 (1963).
38 Abridged Specifications for Processing of Ektachrome ER, MS and Reversal Print Films Through Process ME-4 (Motion Picture and Education Markets Division, Eastman Kodak Company, January, 1966).
39 Beilfuss, H. R., Thomas, D. S. And Zuidema, J. W., “Two New High-Speed Ektachrome Motion Picture Films,” Journal of the Society of Motion Picture and Television Engineers, April, 1966, pp. 344-345.
40 “What’s new in news? A report in full color,” Broadcasting, January 3, 1966, pp. 62-66.
41 Rees, H. L., Vogt, H. W. and Zuidema, J. W., “A new low-contrast reversal color print film,” Presented at 100th Technical Conference of the Society of Motion Pictures and Television Engineers, Los Angeles, Oct., 1966.
42 Burton, G. L. and Bauer, R. W., “Processing of Optical Sound Tracks on Color Films with Emphasis on Silver Sound tracks on Improved Eastman Ektachrome R Print Film.” Presented at 106th Technical Conference of the Society of Motion Picture and Television Engineers, Los Angeles, September, 1969.
43 Clifford, J. D., Bauer, R. W., and Hagenbuch. B. R., “A New Reversal Print Film for Low Contrast Originals.” Presented at 110th Technical Conference of the Society of Motion Picture and Television Engineers, Montreal, Canada, October, 1971.”
(Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 167-179.)
“What is Color Correction?
The Importance of color correction in the process of printing or duplicating color films is something not to well understood by many who photograph and produce 16mm color motion pictures.
“Apparently the term means different things to different people,” suggests General Film Rewind in its December, 1960, issue from which the following information is excerpted:
The University Film Producers Association Nomenclature Committee in its listing of “16mm Terms” (journal of the UFPA, Winter, 1960, issue) gives the following definition:
Color Correction: –1: Alteration of tonal values of colored objects or images by the use of light filters, either with the camera or printer. 2: Lens design which corrects chromatic aberration.
Color correction doesn’t pose too much of a problem in 35mm color work, the Rewind points out; the confusion centers on 16mm color – probably because of the different materials, and therefore, different process which are involved.
In 35mm, the article explains, a color negative is exposed from which 35mm color positives are made – either release prints or an interpositive from which is made the 35mm color internegative. To correct color, each scene is judged against a norm, with a color timer actually viewing how the scene would appear with the normal printing light, and with changes in color achieved by varying the proportion of the three primary colors. The color corrections, or changes, are then achieved in printing a positive direct from the camera negative. This system works rather well, and there is little occasion for review of the results.
However, in 16mm color we have quite a different situation. First, the film exposed in the camera is a color reversal-positive, such as Eastman Kodak’s Ektachrome 16mm film. The selected scenes of the processed camera film are usually edited in A&B rolls, to set up for the use of fade and dissolves in printing. From the edited A&B rolls may be made 1) direct reversal color prints, or 2) a 16mm color internegative to be used in making color positive prints.1 In the first method, both camera and dupe stock are similar. In the second method the negative-positive color duplicating stock is basically different from the reversal camera stock.
Color correction in 16mm film printing is accomplished by the same basic method as in 35mm – by varying the proportion of light from the three primary colors.
So, where does the confusion come in?
On three different points – the mechanical method (How is it done?), the process (What is accomplished?), and on cost (Why does it cost more?).
First, method – How is it done?
The color may be altered, between original film and dupe, by either of two basic methods – known as “subtractive color printing” and “additive color printing.” The former utilizes a single light source in the printer, and the color is varied by the insertion of a filter in the light path. In effect, the filler serves to screen out, or subtract undesirable color variations in the print. If the scene to be printed is too red, the filter will reduce the red values in the normal printing light, allowing more blue and green to come through.
Additive color printing utilizes three separate light sources, each representing one of the primary colors. By varying the quantity of light from, each of the three beams, a new “color mixture” is achieved in the light exposing the dupe stock, and the color tone or separate color content is thus varied within the scene.
Both subtractive and additive systems are used, and each can do a satisfactory job. However, it is generally believed that the additive method provides a greater degree of control. Next, process – What is accomplished?
This is the area of greatest confusion for users of 16mm color film – both as regards just what is done, and how this affects the print. Each of the following operations has been referred to as involving color correction:
Normal timing (measuring of the over- or under-exposure of each scene), and alteration of the volume of the printer light during the printing process to lighten dark scenes, darken light scenes. The purpose is to achieve a more even exposure of the scenes in the print, and professional timing does result in a better looking print. But, it is not intended to alter color tones in printing.
The use of a single filter in printing a show edited from one emulsion, as recommended by the film manufacturer or indicated by laboratory tests, to achieve more normal and desirable over-all color balance in the print.
The use of a filter, or filters, to change the color duplication of a few scenes which are noticeably off-color (usually resulting from exposing daylight film with artificial light, or vice versa, or similar camera errors). This may involve one to a half dozen or so scenes, scattered throughout the edited roll.
The use of filtered light in printing to affect the color duplication of every scene in the edited film. This is “scene-to-scene” color correction – each scene being “read” or judged for color in the same manner it is read or judged for density.
Now, only two of these operations involve color correction. Number 3 might be termed ”problem scene color correction.” Only Number 4 is color correction in the professional sense a scene-by-scene judging of color balance, with the necessary changes made in the additive color printer to achieve a smoothly balanced print.
Obviously, the results achieved will vary with the type of handling, as outlined above. This is one reason why opinions vary so in the 16mm field – we use the term “color correction” in referring to different methods.
This brings us directly to the cost factor – why does it cost more? Here, again, it depends on which of the methods we are considering. There’s no additional charge involved in normal timing of prints, with the resultant variation of the quantity of printer light utilized on printing the different scenes. As mentioned above, the only purpose of this light adjustment is to darken light scenes and lighten dark scenes. Usually the service of preparing for and doing the normal type of release printing is included in the listed price of the print. (In the making of 16mm color workprints, there’s a small additional charge for making a timed color workprint, as compared with the price of a one light color workprint.)
Similarly, most film labs make no additional charge where a single filter is used in a printer to affect the over-all beginning-to-end length of the print. This is a normal requirement included in the usual price of a print.
When laboratories encounter what they call “problem scene color correction,” this involves special handling and additional work, which usually leads to additional costs. It’s possible to set up a printer to vary the color balance of the printing light only for the specific problem scenes, but this requires almost as much time as setting up for color timing of each individual scene. It also requires the use of a specialized additive color printer which is much slower in operation than a standard production printer. The laboratory has two options – omit any charge and absorb the additional cost, or charge on the same basis as for a fully color corrected print.
Fortunately, there’s another simpler and less expensive method for accomplishing the same end-result, if the producer is aware of this possibility and edits his film accordingly. The problem scenes which require similar color correction may all be edited on a third or “C” printing roll. This permits the use of a single filter to achieve the desired color balance for that roll, and the print is charged for on AB&C roll basis – considerably less than the cost of A&B roll scene-to-scene color correction.
When a film is to be set up for scene-to-scene color correction, the individual scenes must be judged, not only for density (involving the total quantity of light to be used in printing), but also for color balance (involving the choice and preparation of the primary color mixture to be used in printing). This involves the judgment of an experienced color timer, the use of specialized equipment, and the setting up of separate control strips for the printer. Then, the edited film rolls are put on an additive color printer, which is considerably slower in operation than standard production printers. Time is the basic cost factor in any business operation, so slower speed in printing means increased cost of production.
Since motion picture printing is a combination of science, art, and personnel opinion, the making of a fully satisfactory color-corrected print may be achieved with the first print, or it may not. It’s entirely possible that two, three or more prints may have to be made where originals involve difficult color-correction problems. Obviously, this, too, adds to the basic costs involved.
Thus far we have been discussing color-correcting the 16mm color reversal print made from a 16mm color reversal original. The same basic factors are involved when the color reversal originals are to be translated into a 16mm color internegative for color positive release printing. Since the color systems are somewhat different, the results of color correction may vary. That is, the same filter that produced a desirable result from a scene reproduced on color reversal film may not provide a satisfactory result in a color positive print. If not, there are two alternative laboratory procedures possible. Either start all over again and make a new color infernegative, or introduce color timing in printing from the existing color internegative. Each procedure involves cost. If a new internegative is made, the costs involved are raw stock, labor, and overhead. If the same internegative is to be used, with additional color correction to be made in printing, the printing speed factor again enters – since the internegative must be taken off the faster production printer and put on the slower color-correction printer.
“In our experience,” says General Film Laboratories, “35mm color negative clearly requires color-correction, and correcting of color is an apparently stable and satisfactory process. The well-exposed 16mm color reversal original film does not require color-correction, except for the occasional problem scene. To judge by the requirements and requests of customers, color correction is standard in 35mm work, but little required in 16mm work. However, like so many occasional requirements, 16mm color-correction is a lifesaver when you really need it!”
1 Also possible to make a 16mm color reversal master from which contact second generation prints can be made. However, this method is little used now that 16mm color internegative-positive process is available – except for special purpose requirements.
(Anonymous (1961): What is Color Correction? In: American Cinematographer, 42,2, Feb. 1961, p. 104 and p. 108.)
“For our comparisons, original photography was done on 35mm Eastman Color Negative Film, Type 5250, and 16mm Ektachrome Commercial Film, Type 7255. The original films, each edited to one-minute projection time, were printed in a number of ways. Duplication from Eastman Color Negative Film was done using Eastman Color Intermediate Film, Type 5253 or 7253, for the master positive and duplicate negative stages. Prints from Ektachrome Commercial originals were made using Eastman Color Internegative Film, Type 7270. All prints from internegatives were made on Eastman Color Print Film, Type 7383.
Since printers need to be of very high quality in 8mm work, some comments on our equipment are necessary. All contact printing was done on either a 35mm Bell & Howell subtractive printer or a 16mm Bell & Howell additive printer, each equipped with internal air jets. An Acme printer was used for optical printing with these lenses:
1:1 103mm Kodak Printing Ektar at f/4
2:1 90mm Kodak Printing Ektar at f/3.8
4:1 75mm Kodak Enlarging Ektar at f/5.6
Slightly sharper results would have been obtained at 4:1 reduction if the Acme printer could readily be modified to accept the 90mm Ektar lens at the proper conjugates. The 75mm Ektar lens needed only an adapting mount, however, so it was used for these tests. In choosing printer lenses, each lens should be tested for sharpness, and then used only at the optimum f/number. Printers must be in perfect condition to minimize weave, unsteadiness, poor contact, and all factors that hurt image quality and are especially apparent in 8mm work.
It is important that each printing stage be optimized if quality is to be preserved in duplicating. Losses are inherent in each transfer of the image, a fact pointing toward systems with the minimum number of printing operations. As a general rule, image reduction should be postponed to the last stages of printing for best quality; that is, the image should be kept as large as possible as long as possible. Logically, then, the best quality would be expected from a 35mm original that was release printed at 4:1 reduction. In practice however, a duplicate negative would usually be required, and with presently available equipment 4:1 release printing may not be economically feasible.
Since the projected area of the 8mm frame is only 20% of that of a 16mm frame, dirt on 8mm prints is extremely objectionable. The only defense against dirt and other physical defects is careful film handling and cleaning techniques. More than once, a stereo microscope was used to clear the printer gate of an apparently invisible wisp of dirt that had printed through an embarrassing number of times before detection.
Enlargements from several of the 8mm films are shown in Fig. 1. These prints, made using 35mm panchromatic negative, are a poor substitute for viewing the actual color motion pictures, but some understanding of relative sharpness and graininess may be gained by comparing 8mm systems in these reproductions.
A rating of the prints compared in our study is given in Table I. Each system is ranked on both quality and practicality factors, and comments on the obvious features of each system are added.
On the basis of sharpness, 16mm original photography is nearly equal to 35mm original photography when their respective 8mm prints are viewed. A number of cross-comparisons are needed to substantiate this statement, but it should be remembered that one less printing cycle is required in 16mm duplicating than in 35mm duplicating. This, together with the limiting response of the print materials at 8mm image size, tends to offset the size advantage of the 35mm original.
Optical release printing is needed at present for satisfactory screen quality. It would be very desirable to use the faster contact-printing system in making release prints, but most viewers consider an optical print from 16mm a necessity for adequate sharpness. Cartoons or other material not containing fine detail might be suitable for 8mm contact release.
Kodachrome II film has been included in this study because it is a film against which customers can judge their purchases in the commercial market. In picture comparisons the color quality and sharpness of the original film are especially prominent; the long tone scale in the original and the differences in grain quality are also important.
Perhaps our experiences can be summarized in these four conclusions, some of which apply to printing in other than 8mm systems.
(1) Optical release printing from a 16mm or 35mm internegative is required for a satisfactory 8mm print.
(2) In 8mm printing a 16mm original gives nearly the same quality as a 35mm original.
(3) In printing through several stages, film size should be kept as large as possible as long as possible for best quality.
(4) An 8mm Kodachrome II original is sharper and of higher quality than any 8mm print from a 16mm Ektachrome Commercial original or a 35mm Eastman Color Negative original.
A number of printing systems were investigated that have not been mentioned. Shown below as print masters is the use of Ektachrome Reversal Print Film, Type 7386; Ektachrome Commercial; and Eastman Reversal Color Print Film, Type 5269:
Each of these films, in either 8mm or 16mm, has some advantage in grain, color quality, or sharpness, but the overall screen quality of the final print is not equal to that obtained in the Eastman Color system. Furthermore, the 8mm commercial market must be one of high volume, a condition requiring the use of lower-cost print materials.
Kodachrome II Originals
In 8mm prints the emphasis is on sharpness. This has led to many inquiries on the use of 16mm Kodachrome II as an original for release printing. While Kodachrome II is certainly sharper than ECO, it is a higher-contrast film designed for direct projection and not as an original for printing. Prints made from Kodachrome II onto 7270 or 5269 are very high in contrast, except for a low relative red contrast. The contrasts can be made nearly equal by use of special printing filters, but the prints, while sharp, still have high overall contrast.
In addition, our comparisons of prints from Kodachrome II and ECO show considerably less sharpness difference than does a direct comparison of the two originals. The sharpness of Kodachrome II has reached a level where the ability of the printers to transfer the finest detail is a significant factor. Ideally, further improvements in either original or print films should be accompanied by improvements in printing techniques.
After seeing these prints, most viewers agree that for acceptable quality an 8mm print must be prepared from a 16mm or 35mm prior stage in an optical reduction printer. This printing procedure is generally slow and expensive, although there are exceptions in some laboratories. In general, however, it would be advantageous to contact-print from an 8mm internegative, printing two or four rows of 8mm pictures at once. While we cannot yet do this and produce satisfactory quality, examination of contact-printing methods is an active program throughout the industry.
Interest in contact printing is further increased by the question of photographic vs. magnetic soundtracks. If equipment and films would permit four photographic soundtracks to be printed in a single-pass contact printer, considerable reduction in laboratory costs would be realized compared to the present striping and recording operation using magnetic materials. A one-pass picture and sound printer using 35/32mm film with four rows of 8mm pictures is an attractive goal for further development work. Many questions arise, however, when considering photographic sound – the kind of soundtrack, method of recording, equipment for playback, and wear characteristics. These problems, along with many others, must be solved before photographic sound for 8mm can be a practical reality.”
(Keene, G. T.; Clifford, J. D. (1962): Commercial Systems for Making 8mm Prints. In: Journal of the Society of Motion Picture and Television Engineers, 71,6, pp. 447–449.)
Light entering a multilayer coating is scattered to some degree by the turbid gelatin-silver halide medium. In the case of a material with the conventional layer arrangement (the blue-sensitive emulsion on top), some of the blue light is scattered by multiple reflection among the silver halide grains in the top layer and by back reflection from the interface between the blue-sensitive emulsion layer and the yellow-filter layer. Similarly, the green and the red light are scattered by the overlying emulsion layers and by back reflection at the various interfaces. In general, the light is scattered progressively further as it penetrates deeper and deeper into the multilayer structure. As a consequence, the cyan dye image tends to be less sharp than the overlying magenta and yellow dye images and this can result in the formation of cyan fringes along edges in the image.
One important means for decreasing this optical scattering is to reduce the thickness of the coating structure, and it is largely for this reason that efforts continue toward finding ways to make the emulsion layers as thin as possible. Much has already been accomplished in this direction. To cite a single example, the emulsion layers of Ektachrome Commercial Film, Type 7255, are less than half as thick as those of the original Kodak Ektachrome Sheet Film, E-1.
In a color picture, the magenta dye image carries the greatest proportion of the sharpness information because the eye has its greatest sensitivity in the green region of the visible spectrum, and, in a subtractive color film, the amount of green-light absorption is controlled by the magenta dye. Hence, the optimum picture sharpness in any given system can be obtained if the magenta dye image is located in the top layer of the multilayer structure. This is the reason for the unconventional layer arrangement in Eastman Color Print Film, Type 5385. However, it is not always feasible to use the magenta-on-top arrangement because of requirements other than sharpness which the film must fulfill.
In addition to the optical effects, there are also chemical factors which affect the sharpness of color images. One of these is the diffusion of oxidized developer mentioned earlier in connection with graininess. Still another mechanism which can cause the deposition of dye at a site some distance from an exposed grain involves the dissolution of some of the silver halide during color development. This dissolved silver halide can be reduced at some distant site by the process called “physical development,” resulting in the formation of oxidized developer and deposition of
dye. Thus, the dye is formed at some distance from the exposed grain and image sharpness suffers accordingly. To learn the mechanism of these various effects which reduce the image sharpness, and to find techniques for minimizing them, have been the objectives of continued research. Over the years the success of these studies has led to steady improvement in the sharpness of color photographic images, and continued progress can be expected.”
(Vittum, P. W. (1962): Chemistry and Color Photography. In: Journal of the Society of Motion Picture and Television Engineers, 71,12, pp. 937–941, on p. 940.)