Film vs Digital

The relative merits of film vs digital images has often been the subject of debate.  With improvements in sensors and concomitant improvements in exposure latitude, tone, scale, and resolution, the debate is less pressing and will become less so as film supplies and film-processing facilities dry up.  But occasionally I run into someone stubborn in his allegiance to film photography.  In terms of ease of processing, there is no contest: digital photography wins hands down.  Another argument favoring the digital medium is the ease with which the image can be manipulated, although some consider this a definite minus, suggesting that there is something fraudulent about an image that has been adjusted in Photoshop.  Arguments stipulating the superiority of the film over digital seem to be based on a yardstick of perfection that is film-based— the idea that there is something pristine, truthful and unadulterated about a photographic image.  My view on the subject is that the quality of the final print is the sole consideration, and it doesn’t matter how this print was arrived at.  The final result is, in any case, an abstraction from the original subject.

Film purists overlook an important consideration with regard to making the final printed image based on silver halide photography—namely, that there has been manipulation of the image from negative to final print.  In fact, Ansel Adams, the paragon of artistic photography, tinkered with the image both during development of the negative and in producing the final print, as is well known. 

Black-and-white film photography experts used an unsharp copy of a negative printed in register with 'unsharp mask' filter, which takes its name from the old technology and is used for the same purpose.  At Kodak we tinkered with film and developer formulations to enhance the final image.  For example, with proper formulation of a developer, it is possible to repress development of a negative in the region of a sharp edge, a so-called “adjacency effect,” that gives a net effect on printing of increased edge contrast and apparent image sharpness.  In color film photography, particularly with reversal film products such as Kodachrome and Ektachrome, we created film developer combinations in which development in the top two (blue and green sensitive) layers affected development in the bottom (red sensitive) layer, resulting in a significant increase in red image contrast, producing the brilliant reds for which those products were noted.  Green reproduction was enhanced in similar fashion.  The point of all this is that conventional film photography was full of little tricks and manipulations (not to mention retouching to remove subject imperfections) that are also available in Photoshop. Digital photography is not unique in its capabilities for image manipulation.

The one area in which film may excel is resolution and freedom from moiré effects.  Resolution in digital photography is limited by physical sensor size and pixel density, a combination that controls cost.  Costs of large (e.g.; 35 mm. frame size) sensors have been coming down, but a full-frame sensor still adds several hundred dollars to camera cost.  Where pixel densities have increased without a concomitant increase in frame size, the resulting crowding of more pixels into a limited space can lead to undesirable limitations in exposure latitude and tone scale because of pixel-to-pixel interactions as a result of propinquity.

The moiré problem arises from the regular pattern used in depositing the photosensitive elements in the digital sensor.  This problem is obviated in film photography because the photosensitive elements (silver halide grains) are randomly distributed.

Both digital and silver halide suffer from intrinsic noise problems, particularly in dim light recording.  With silver halide, noise arises from the fact that the largest grains of silver halide are the most sensitive, and are the only ones exposed at low light levels; i.e.;  noise is caused by granularity.  In the case of digital sensors, stray electrons produced by signal amplification are responsible for noise.  In both cases, increasing sensitivity (ISO rating) in order to improve light-light recording capabilities gives rise to more noise.  In the case of film photography, faster emulsions require larger silver halide grains, hence more noise (we referred to this at Kodak as “the speed/grain problem”); with regard to digital sensors, higher sensitivity is achieved by using higher signal amplification, which introduces more stray electron and more noise.

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