A review on the progress in photography in the year of 1957; about cameras, lenses and their accesories, light sources, sensitive materials, theory of photographic sensitivity, sensitometry, processing, scientific photography, cinematography, and colour photography.

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It seems that in practical emulsions silver gelatinate envelopes are formed at boundaries between matrix gelatin and emulsion grain.
With use of anelectron microscope we observed how silver gelatinate envelopes change when the photographic emulsions were printed out with matrix gelatin or without matrix gelatin.
It appears that some of halogen atoms, liberated in print-out process, slightly destroy the silver gelatinate envelopes, but most of these are accepted in matrix gelatin around the silver gelatinate envelopes and halogeno-gelatin envelopes are formed.
Chemically non-sensitized emulsion was not different from chemically sensitized emulsion as to feature of silver gelatinate envelopes and their behaviors in print-out process.

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Measurements of the optical absorption spectra of silver chloride and silver bromide crystals and the sensitometric studies under various conditions on some typical photographic emulsions were taken place for the purpose of figuring out the mechanism of the photographic sensitivity.
It is evident that the first two maxima of the absorption curve in the ultraviolet region (Fig. 1) are originated in the exciton band. The underlying absorption band of smaller absorption constant (Fig. 2), which is not structure sensitive, is resulted from the transition of electrons between full-band and conduction-band.
The results of the sensitometric studies on the photographic emulsions, which are summarized in Fig. 3 and Fig. 4, are discussed from the view-point of the sensitivity theory proposed by Mitchell in 1957. The mechanism of the production of the sensitivity centre on the chemically sensitized emulsion microcrystals during the second ripening, the reciprocity failure characteristics of r and the three types of the mechanism of development each of which shows the characteristic kinetics curves of development are interpreted.

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Several reports have been published on the optical noise reduction. They all adopt the method of cutting off the spatial high-frequency component of noise. The method is effective for periodic optical noise such as those of half tone dots, however it would not produce very good effect in the case of optical noises like those of the photographic silver grain. So we have come to the conclusion that in order to reduce the photographic noise, we should rather reinforce the high-frequency component of noise than cut it off. We have, therefore, reduced the noise, reinforcing the high-frequency component -of noise by using a special enlarger with point sources.

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In the previous paper, the desensitization by pressure deformation of silver halide grains of emulsions, and the relation between pressure and latent image distribution were reported.
In this paper, the following cases were investigated:
1) Photographic pressure effect on the photographic material in the range of 0-100% humidity, and also the measurement of Young's modulus of gelatin films of that conditions.
2) Pressure effect of silver bromide emulsions containing various amount of T1Br, AgI and AgCl respectively, and also relation between pressure and Vicker's hardness of fused silver bromide crystals of the same concentration of T1Br, AgI and AgCl.
Results;
1) Pressure effect of the former and Young's modulus of gelatin films, decreased with increasing relative humidity.
2) Pressure effect on silver bromide emulsions was inversely proportional to increase the concentration of T1Br, AgI and AgCl, but the Vicker's hardness of fused AgBr crystals, proportioal it.
The following conclusion may be drawn from experimental results ;
Photographic pressure effect is proportional to the hardness of gelatin films, but inverse of the hardness of silver halide crystals of emulsion.

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Silver chloride emulsions are prepared by three different compositions A, B and C and their gamma-ray sensitivity as well as the light sensitivity are studied.
Emulsion A is prepared by simultaneous addition of sodium chloride solution and silver nitrate solution into gelatin solution in 5 minutes at 48°C, and it has low sensitivity and high contrast. Emulsions of series B and C are mixed by dropping silver nitrate solution into sodium chloride-gelatin solution. The gamma-ray sensitivity of emulsions of the composition A without ripening is lower than that of emulsions B or C, but the sensitivity of emulsions of the series A can be increased by ripening of 30-180 minutes. Influence of the ripening on the gamma-ray sensitivity appears smaller for emulsions of the series B or C, even though the ripening increases the threshold light sensitivity of the emulsions. It is suggested that the gamma-ray sensitivity of the emulsions depends to some extent upon the sensitivity in the higher light exposure region.
It is also demonstrated that latent image fading of silver chloride emulsions depends on the nature of gelatin in emulsions, and fading phenomena are likely not affected by the temperature of mixing of emulsions.
We concluded that the silver chloride emulsions, including gaslight paper, become developable when they are irradiated by gamma-rays of Co⁶⁰ of the order of 10 to 10³ R and the emulsions are available for gamma-ray dosimetry in this range.

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