F76 plus FILM DEVELOPER TEST REPORT with EFKE FILM

Purpose

The purpose of these tests is to establish nominal developing times for 35 mm and 120 mm EFKE film using Clayton F76 plus Developer when the film was exposed at its manufacturer’s rated ISO value.

Exposure Methodology

Efke 35 mm film ( ISO 25) was used to shoot a photographic target. This was a MacBeth Color chart exposed near noon, in full sun, at 39 degrees, 40 minutes north, on May 21, 2004. A series of shots were also taken of a scene containing a white shed with a black eagle, a green leafy shrub and black shadows. The MacBeth target series consisted of one exposure at the meter indicated setting, another at +1ƒ-stop and another at -1 ƒ-stop. The 35 mm film was exposed using a Nikon F100 camera at the manufacturer’s ISO setting and automatic “P” mode. The camera was mounted on a Bogen tripod with a cable release used to avoid camera shake. At the completion of the exposures, the film was removed from the camera and stored in a sealed plastic bag at 4°C.

Upon completion of the 35 mm exposure series, the camera was removed and a Mamiya RB camera was mounted. Efke 120 mm film (ISO 100) was loaded and the series of shots was repeated. At the completion of the exposures, the film was removed from the camera and stored in a sealed plastic bag at 4°C.

Processing

All film was processed using a Jobo CPA2 processor equipped with the Jobo “lift” at 20°C. The temperature was established using the Jobo temperature control circuits and checked using a separate thermometer. Rotation was established using the Jobo rotation setting “F”. Both temperature and rotational settings remained unchanged during the course of all the tests.

The Clayton F76 plus Developer was diluted using tap water in volumetric glassware at a dilution of 1+9. Kodak Indicating Stop Bath, diluted 8+492, Sprint Fixer and Fix Remover diluted 1+9 were used to complete development. A liter of F76 plus Developer was prepared; aliquots of 300 mls were used as a “one shot” application and discarded after each use. Stop bath, fixer, and fix remover were reused during the tests as only small amounts of film were processed for each application.

Portions of film were clipped from the 35 mm and 120 mm rolls in a darkroom and loaded in a Jobo 2500 series tank. The remaining film was sealed in a black, light tight bag and stored in the darkroom between developing sessions. All film was processed on the same day.

The loaded tank was placed on the Jobo processor and allowed to rotate at the “F” setting for a 120 second period to stabilize the temperature. One minute prewash with tap water preceded the addition of the developer. The 35 mm film was developed according to the times indicated in Table 1.

Table 1. 35 mm Efke Film Developing Times
TEST	1+9 DILUTION	1+19 DILUTION
1	15.0 minutes	20.0 minutes
2	10.0 minutes	15.0 minutes
3	7.5 minutes	12.5 minutes
4	6.0 minutes	10.0 minutes
5	5.5 minutes	8.0 minutes
6	5.0 minutes	N/A

Efke 120 mm film (ISO 120) was processed according to the times indicated in Table 2.

Table 2. 120 mm Efke Film Developing Times
TEST	1+9 DILUTION	1+19 DILUTION
1	30.0 minutes	30.0 minutes
2	20.0 minutes	25.0 minutes
3	13.5 minutes	22.0 minutes
4	15.0 minutes	20.0 minutes
5	12.0 minutes	18.0 minutes
6	10.0 minutes	N/A
7	5.0 minutes	N/A

Following development, stop bath was added for a one minute period. The film was then fixed for a five minute period to ensure complete fixing. The film was given a water wash for one minute, then a three minute wash with fix remover. This wash was followed by a series of three rinses with tap water, then a thirty second wash with diluted Photo-Flo. The film was then removed from the tank, squeeged, and dried in a Jobo Mistrail air dryer at room temperature for a minimum of six hours.

FILM EVALUATION

Two different printers evaluated the film on a light table on two different days. Their results were not shared until after the preparation of this report. Densitometry was performed on clips at a separate time. The spaces between images were used to determine base plus fog levels. All densitometry measurements were corrected by subtracting base plus fog.

Efke 35 mm (ISO 25)

F76+ at 1+9 dilution

Visual evaluation of the clip test segments indicate that 5½ minutes gave excellent results with a great deal of detail and very nice contrast. Interestingly, there was significant visual difference between 5.0, 5½, and 6.0 minutes of development.

Densitometry confirmed the visual evaluation and indicated that the maximum corrected density differences (transmission density minus base plus fog) between “white “and “black” on the MacBeth color chart at 5½ minutes.

Push processing up to two stops and pull processing by at least one stop should be feasible as well. Push processing by one stop should increase time from 5½ minutes to 6½ minutes; two stops would probably increase to 7.0 minutes.

IT MUST BE NOTED THAT THESE PUSH AND PULL TIMES HAVE NOT BEEN TESTED.

F76+ at 1+19 dilution

Film clips from the same roll used in the 1+9 dilution evaluations were tested at the 1+19 dilution of the developer. Visual evaluation of the clip test segments indicate that 12½ minutes of development gave the best results. Densitometry performed as above, confirmed this evaluation.

Densitometry results became non-linear at extended developing times. Normally, this would indicate possible exhaustion of the developer. However, since only small segments of film were developed, using the full volume of 300 mls, this is not likely. At present, this is unexplained.

Efke 120 mm (ISO 100)

F76+ at 1+9 dilution

Visual examination of the clip test segments indicate that 13½ minutes is ideal for this film. Differences between 12.0 and 15.0 minutes were apparent by visual inspection. As with the 35 mm Efke film, push and pull should be feasible. A push of one stop should extend development time to 15 minutes, while a pull of one stop should decrease development time to 12 minutes.

IT MUST BE NOTED THAT THESE PUSH AND PULL TIMES HAVE NOT BEEN TESTED.

F76+ at 1+19 dilution

Film clips from the same roll used in the 1+9 dilution evaluations were tested at the 1+19 dilution of the developer. Visual examination of the film indicated that 22-23 minutes is a very good starting time, however differences between 20 minutes and 22 minutes is not great. Twenty five minutes should be considered excessive as indicated by the bleed of frame numbers-although the images appear to be quite usable.

As above, push and pull processing should be very feasible with a one-stop push probably requiring an increase to 25 minutes while a two-stop push will probably need 30 minutes. A one stop pull will probably decrease development time to 20 minutes and a two-stop pull will decrease development time to 18 minutes.

IT MUST BE NOTED THAT THESE PUSH AND PULL TIMES HAVE NOT BEEN TESTED.

Summary

The following development times are recommended:

JOBO CPA2 PROCCESSOR

Efke 35 mm (ISO 25) 1+9 5½ minutes at 20ºC

Efke 35 mm (ISO 25) 1+19 12½ minutes at 20ºC

Efke 120 mm (ISO 100) 1+9 13½ minutes at 20ºC

Efke 120 mm (ISO 100) 1+19 22½ minutes at 20ºC

The information in this report has been provided by Clayton Chemical Company. All reports are independent submissions.