This standard specifies the method for measuring the ISO sensitivity of negative film for color photography. It makes specific provisions on safelight, sample exposure conditions, sample processing, density measurement, sensitivity calculation method and product sensitivity determination method. This standard applies to the sensitivity measurement of color photographic negative film for photography, which can be used to print reflective color photographs and can also be used to print color transparent films. This standard does not apply to color negative film for aerial photography and color film used to make color intermediate films. The sensitivity measurement of color movie negative film can refer to this standard. GB/T 2924-1995 Determination of ISO sensitivity of negative film for color photography GB/T2924-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of ISO speed of colour negative films for photography This standard is equivalent to ISO 5800-1987 Photography - Determination of ISO sensitivity. 1 Subject content and scope of application
GB/T 2924-1995
Replaces GB 2924-B2
Color photographic negative film - Determination of ISO sensitivity". This standard specifies the method for measuring ISO sensitivity of colour negative films for photography. It makes specific provisions on safety lights, sample exposure conditions, test batch processing density measurement, sensitivity calculation method and product sensitivity determination method. This standard applies to the sensitivity measurement of colour negative films for photography. This negative film can be used to print reflective colour photos and can also be used to print colour transparent films. This standard is not applicable to color negative films for aerial photography and color films used to make color intermediate films. The sensitivity measurement of color motion picture negative films can be carried out by referring to this standard. 2 Reference standards
Geometric conditions for photographic transmission density measurement
G11500
Spectral conditions for exposure density measurement
CB11501
GB/T15061 General rules for the determination of sensitivity of silver salt photosensitive materials Part 1 Exposure conditions for samples applicable to incandescent tungsten lamps and simulated daylight
3 Definitions
3.1 Sensitivity (S)
Quantitative expression of the response of photosensitive materials to light energy under specified exposure, processing and density measurement conditions. 3.2 Exposure (I)
Integral of the illuminance on the film over the exposure time, measured in grams per second, represented by the symbol H. 4 Sampling and storage
When determining the IS sensitivity of the product, the rationality of sampling should be considered first. The results of the sample should represent the average sensitivity of actual use. This requires regular testing of different batches of products under the conditions specified in this standard. Before measurement, the samples are stored for a period of time according to the conditions recommended by the manufacturer to simulate the average period of normal use of the product. Instructions for use:
1) The provisions of ISO 5800 are not applicable to the sensitivity measurement of color film negatives. This standard considers that the sensitivity of color film negatives measured by this method can be used as a parameter for photography.
Approved by the State Administration of Technical Supervision on December 20, 1995 and implemented on August 1, 1996
5 Test methodWww.bzxZ.net
5.1. Principle
GB/T29241995
The sample is exposed and processed according to the following regulations, the density value is measured from the obtained image, and the sensitivity characteristic curve is drawn. The sensitivity is calculated from the characteristic curve.
5.2 Safety light
In order to eliminate all possible effects of "safe light" on sensitivity measurement, sampling, warm light and processing should be carried out in complete darkness. 5.3 Dawn
Comply with the relevant regulations of GB/T15061. The exposure time can be selected between 1/1000--1/10s. 5.4 Processing
5.4.1 Product Balance
During the interval between exposure and processing, the samples should be kept in an environment with a temperature of 23℃±2C and a relative humidity of 5(±5)%. Amateur films should be processed within 5-10 days after exposure, while professional films should be processed within 4h to 7d. 5.4-2 Processing Specifications
Since the chemicals and equipment used in the processing of color negative films are very extensive, this standard does not specify the processing conditions. However, when film manufacturers provide ISO sensitivity values, they must also provide the processing conditions used to determine the product's ISO sensitivity, which include the processing procedures, the chemical solution formula used in each procedure, the processing temperature and time, and the stirring equipment. Although different sensitivities can be obtained by changing the processing, other sensitive and physical properties will change as the sensitivity changes. For example, after strengthening processing, along with the increase of sensitivity, the film's haze rises and the particles become coarser. 5.5 Intercept measurement
Use a densitometer whose geometric conditions and spectral conditions meet the requirements of GB11500 and GH11501 respectively to measure the standard M state diffuse transmission density of the processed sample image. The symbols of these conditions are: b, (90° opal glass; Sh: ≤10M)
or D (≤10°S: 9° opal glass + M)
In order to reduce the influence of image unevenness, the area of ​​the density measurement hole should be at least 7mm2 and should be at least 1nm away from the edge of the exposure area.
5.6 Evaluation
5.6.1 Sensitivity measurement curve
Use the red, green and blue (D) measured in 5.5 as the vertical coordinates and the corresponding exposure logarithm (lgH) as the horizontal coordinates to obtain the three sensitivity characteristic curves of red, green and blue as shown in the figure below. 5.6.2 Small density
Along with the exposed film with the determined sensitivity characteristic curve, a sample of the same film that has not been exposed is processed at the same time, and its green and blue state densities are measured, which is the minimum density of the film (including gray fog density, film base density and Limaske density). 5.6.3 Determination of exposure value H. at the reference point of sensitivity measurement From the three red, green and blue characteristic curves determined in 5.6.1, find the density value 0.15 above the minimum density and the exposure values ​​HR, Hc and H required to produce these density values. The arithmetic value formula for calculating 1 is as formula (1), and the logarithmic value formula is as formula (2): Instructions for use
1) These contents of IS () 5800 have been converted into GB15061. Omitted here, 2) TS058 (0) makes specific provisions for the exposure time. According to the usage in my country, this standard sets the exposure time as 1/100~-1/10s or
GB/T2924—1995
Egff.
Color negative film sensitivity characteristic curve
H.-VHaXH.
IgHe+lgH
In the formula, II, the exposure amount of the lowest sensitivity layer among the first to third layers, that is, the largest value among Hs, Hc, and H, 5.6.4 Formula for calculating the sensitivity of 1S0
Color photographic negative film ISO The arithmetic value of sensitivity is obtained from formula (3), and the logarithmic value is obtained from formula (4): S°-1+10lg
Where S is the arithmetic sensitivity,
is the logarithmic sensitivity.
+++* (4)
6 Product classification
6.11 ISO sensitivity scale
GB/T 29241995
The sensitivity scale is as follows. The sensitivity calculated by the formula specified in 5.6.4 should be adjusted according to the following table. As long as the H value is known, the ISO sensitivity can be directly found from the following table.
Logarithm of sudden light IgHm
— 0. 70
— 0. 60
— 0. 50
— 0. 61
Arithmetic value
ISO sensitivity
Logarithm
GB/T 2924—1995
6.2 Product sensitivity
The ISO sensitivity of the product is different from the ISO sensitivity of a specific sample. Products from different batches should be sampled according to the above regulations, stored and tested, and the arithmetic mean value of all measured exposures I1 should be calculated, and then summarized in Table 1 to obtain the product's ISO sensitivity. Because ISO sensitivity depends on exposure and processing conditions, these conditions should be indicated when providing ISO sensitivity. 6.3 Uncertainty
Equipment and processing techniques related to measuring film sensitivity should be properly calibrated to ensure that the error of exposure 1gH is less than 0.5.7 Product marking and labeling
The sensitivity of the product measured and normalized by the method described in this standard can be marked as IS sensitivity, which can be expressed in three forms: IS0100.ISO21° or Is0100/21°
Since the sensitivity depends on the lighting source, exposure time and processing conditions, these conditions should be indicated if possible when providing the sensitivity according to this standard.
Additional remarks:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard was normalized by the First Film Factory of China Lucky Film Company. This standard was drafted by the China Film Science and Technology Research Institute, the First Film Factory of China Lucky Film Company, and the Photosensitive Materials Testing Center of the Ministry of Chemical Industry.
The main drafters of this standard are: Mou Xiufang, Fu Zhijian, and Gou Xizeng.
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