There is debate over which of the two formats, digital or film, is superior. It cannot be said that either of the formats is superior to the other in every way. Rather, each of the formats has its own specific advantages. This article discusses those points.

There are numerous measures which can be used to assess the quality of still photographs. The most discussed of these is spatial resolution, i.e. the number of separate points in the photograph. This is measured by how many millions of picture cells make up the photo.

The comparison of resolution between film and digital photography is complex. Measuring the resolution of both film and digital photographs depends on numerous issues. For film, this issue depends on the size of film used (35mm, Medium format or Large format), the speed of the film used and the quality of lenses in the camera. Additionally, since film is an analogue medium, it does not have pixels so its resolution measured in pixels can only be an estimate.

Similarly, digital cameras rarely perform to their stated megapixel count. Other factors are important in digital camera resolution such as the actual number of pixels used to store the image, the effect of the Bayer pattern of sensor filters on the digital sensor and the image processing algorithm used to interpolate sensor pixels to image pixels. Estimates of the resolution of a photograph taken with a 35mm film camera vary. However, there exist many estimates around 12 Megapixels. It is possible for more resolution to be recorded if, for example, a finer-grain film is used or less resolution to be recorded with poor quality optics or low light levels. This would place 35mm film cameras roughly equivalent with top-of-the-range digital cameras (as of 2006).

However, while 35mm is the standard format for consumer cameras, many professional film cameras use Medium format or Large format films which, due to the size of the film used, can boast resolution many times greater than the current top-of-the-range digital cameras. For example, it is estimated that a medium format film photograph can record around 50 Megapixels, while a Large format films can record around 200 Megapixels (4x5 inch)which would equate to around 800 Megapixels on the largest common film format, 8x10 inch.

The resolution of modern black and white slow speed film, exposed through a high quality prime lens working at its optimum aperture yields usable detail at a scanned file size of greater than 30 megapixels. With consumer 35mm color negative film an effective resolution of over 12 megapixels is achievable and in an inexpensive 35mm point and shoot camera a resolution of over 8 megapixels may be achieved.

When deciding between film and digital and between different types of camera, it is necessary to take into account the medium which will be used for display. For instance, if a photograph will only be viewed on a television or computer display (which can resolve only about 2 Megapixels and 1.3 Megapixels, respectively, as of 2006), then the resolution provided by a low-end digital cameras may be sufficient. For standard 4x6 inch prints, it is debatable whether there will be any perceived quality difference between digital and film. If the medium is a large billboard, then it is likely that the extra resolution of a medium or large format will be necessary. For larger prints, the extra resolution of a good 35mm film photograph may be desirable.

It should be noted that a special case exists for long exposure photography - Currently available technology contributes random noise to the images taken by digital cameras, produced by thermal noise and manufacturing defects. For very long exposures it is necessary to operate the detector at low temperatures to avoid noise impacting the final image. Film grain is not affected by exposure time, although the apparent speed of the film does change with longer exposures.

Convenience and Flexibility

This has been one of the major drivers of the widespread adoption of digital cameras. Before the advent of digital cameras, once a photograph was taken, the roll of film would need to be finished and sent off to a lab to be developed. Only once the film was returned was it possible to see the photograph. However, most digital cameras incorporate an LCD screen which allows the photograph to be viewed immediately after it has been taken. This allows the photographer to delete unrequired photographs and offers an immediate opportunity to re-take. When a user desires prints, it is only necessary to print the good photographs.

Another major advantage of digital technology is that photographs can be instantly moved to a personal computer for modification. Many digital cameras are capable of storing pictures in a RAW format which stores the output from the sensor directly rather than processing it immediately to an image. When combined with suitable software, such as dcraw, this allows the user to configure certain parameters of the taken photograph (such as sharpness or colour) before it is "developed" into a final image. More sophisticated users may choose to manipulate or alter the actual content of the recorded image. Film photographs may be digitised in a process known as scanning. They may then be manipulated as digital photographs.

Price

The two formats (film and digital) have different emphases as regards pricing. With digital photography, cameras tend to be significantly more expensive than film ones, comparing like for like. This is offset by the fact that taking photographs is effectively cost-free. Photographs can be taken freely and copies distributed over the internet free of charge.

This should be contrasted with film photography where good-quality cameras tend to be less complicated and, therefore, less expensive. But this is at the expense of ongoing costs both in terms of film and processing costs. In particular, film cameras offer no chance to review photographs immediately after they are shot, and all photos taken must be processed before knowing anything about the quality of the final photograph.

There are costs associated with digital photography. Digital cameras use batteries, some of which are proprietary and quite expensive. While they are rechargable, they do degrade over time and must be periodically replaced. Although there is no film in digital cameras, there is the requirement to store the images on memory cards or microdrives which also have limited life. Additionally, some provision for storage of the digital image must be made. In general this would be either an optical disc produced by a shop or photofinisher, or by the photographer on a computer system. If physical prints are to be made they can either be purchased from a photofinisher, or produced by the photographer.

The price differential between the two formats is often dictated by the intent of the photographer and the purpose of his or her work.

About the Author

Philip Wakefield writes on photography techniques. For more articles about your hobby go to Skills in Photography also for a great read Digital Photography book