Photo

 
    2. Gnome. Initially emphasized acutance of this picture is determined by use of high-quality wide-angle camera and shooting at macro mode. The file was originally coloured but when processing the picture I liked to accentuate the graphics of image. I discoloured it. Camera Model Name - Nikon coolpix 5000. Sensitivity 100 ACA. Exposure 1/125 sec. Aperture value – 5,6.
    From the very beginning of photography existence, acutance became one of the most important tools of a photographer. Acutance is a bosom-friend. It is everywhere. At the same time it is nowhere. Acutance is a two-faced Janus, it can be both evil and good. The reason is that acutance can be different. Acutance also depends on the quality of optical glass and camera lenses characteristics. It slips away from photographer disappearing in environment: air, water, photoemulsion. Even having forced its way through the film’s gelatine coating, which is charged with silver halogenide crystals, to the substrate, the light manages to reflect from it and blur the border between light and dark parts of the image.
Before digital photography came into service, experts distinguished two types of acutance: visual acuity and photographic acutance.
   Acuity of optical image is the degree of distinguishability of points and outlines. It depends, first of all, on accuracy of optics focusing.
   Second, it depends on aberrations, i.e. defect of neighboring point form. That happens in any camera lens. However some lenses can depict almost ideal round point, while others will display an ellipse with coloured halo around instead of it. By the way, these coloured halos are called coloured aberrations. They appear because optical glasses deflect different types of light rays in different ways. Third, it depends on internal dispersion of light inside the camera lens. And finally, acuity depends on depth of resolution peculiar to different lens. There is no such optics that could depict with equal acutance objects which are situated in different distance from the camera.
   Photographic acutance is the degree of blurriness of borders between brightly lit and dark parts of photographic image. In epoch of film photography the photographic acutance depended on the film’s characteristics, accuracy of exposure, and chemical treatment while developing the film. Even the best modern films produce a slight blur on the boundaries between objects.
   Since digital photography came into service great changes have happened in customary views of acute and blurred things. Photographic acutance disappeared. It disappears together with silver photography. There is no dispersion of light inside the matrix, therefore there is no boundary blur. In return, there is mathematical weaving that influences on image acutance greatly. We’ve got digital acutance instead of the photographic one. The digital acutance has peculiar contrasting, not blurred outlines (See photo 3).