Virtual Graphic Artist Webzine: COmparing chemical & digital film

Comparing chemical and digital film

The emulsion on our conventional chemical film is the media for our photographic images. Traditional chemical film is actually an emulsion attached to a plastic base and the base is the storage system. The emulsion is light sensitive and must be handled in total darkness. Chemical film can be exposed only once (unless you are creating special effects) because a chemical reaction takes place the moment light strikes the film. Chemical film can be ruined by the slightest bit of stray light causing a problem known as fogging. The film does not know the difference between a carefully chosen or focused camera exposure and random stray light. The result of an exposure is a state known as latent image. Chemical processing in developers and fixers convert the latent image into a stable negative.

You purchase film in convenient rolls placed in light tight containers ready for use. Because of chemical reduction which is a part of the process itself, film has a shelf life. It lasts just so long and after that it cannot produce a perfect print. In such a case, instead of facing unpredictable results you may prefer to throw outdated film away and buy fresh film. Just load it into the camera and start shooting pictures. Your responsibility is to understand how light affects the chemical emulsion and, obviously, to control it. Using various controls to adjust and control the light striking the film is actually the skill of the photographer. But you don't have a second chance unless you use another frame of film. Mistakes can be costly because of the expense of materials. Every beginning photographer must waste a pile of film before they understand the process well enough to ensure that exposures will eventually be nice pictures.

The molecules that make up the latent image have been changed but we still cannot see the picture because the film is still light sensitive. In order to see the image we must process the film using a highly controlled procedure of chemically reducing the emulsion. The process is time, temperature and chemical concentration sensitive requiring great skill. Otherwise, the image will not be processed correctly and, of course, the image will be less than perfect or even unusable. There is more than a century of scientific experimentation behind the average chemical photograph. The final problem was that because of the complexity, processing color film was generally beyond the range of the average photographer.

The last consideration is that many times, the film from the camera was not the final product. It was usually a negative. This resulted in an additional photofinishing step to expose and process the negative onto paper coated with light sensitive emulsion. The result of this process was a print you could hold in your hand and admire. Well, that is if all went well! Another system, the transparency or color slide, required additional steps of chemical magic to reverse the negative so that we would see the final image on film.

In all, the chemical film process was very complicated and tedious requiring much expertise and experience. Many people pursued this endeavor as part of their own photography hobby or business. It is also an expense for you have to keep buying it.

Digital Film

The first and really big difference is that digital photography does not use film in the same sense as the chemical process. Digital film is actually a data file that represents the image as mathematical bits and bytes. There are no consumable rolls of plastic, no negatives and therefore, no processing chemicals. It is not possible to accidentally scratch digital film. It is, however, much easier to lose an image by accidentally deleting it, overwriting (saving a different image with the same file name), or even having your disk crash losing all images in the process.

So what is digital film? In the digital world, images are defined mathematically and not physically on emulsions. Therefore, digital film can be thought of as the resulting data files that are the output of exposure. Just strings of binary 0's and 1's that define a specific bit of information. Put 24 of them together and you have a binary number that can define the color for a single pixel. Put a lot of strings of 24 together and you have the data for a picture. There is no physical form for digital film, but it does exist as a huge flow of numbers that define the individual pixel colors and some control that tells the computer how to assemble the pixels to form the picture. The data will remain in your camera's memory until you turn it off. Then it will disappear into the nothingness of the virtual world. And why not? It never really existed in the first place. Once exposed the data must be transferred to some sort of computer storage media such as floppy disks, SmartMedia or even hard drives. These systems all have one thing in common, they maintain the binary data when the camera is not running. Eventually, the data is transferred to the computer where you may do with it as you wish. Print the picture, adjust it in a program like Photoshop or even attach the data to an e-mail or web page.

The trick to digital film is the requirement of a system of storing the data file in a form that will remain after the camera is turned off. This may be Flash Memory, special computer chips that keep the digital information without the power from the camera. Another system used by Sony is to transfer the data to common floppy disks. A storage system is absolutely necessary unless your camera is attached to your computer with wires. If you think of your storage media as digital film, go right ahead and do so. In your camera you may only hold one picture in memory and that's not very practical. It must be transferred to a storage media freeing up the camera memory for another picture. This is not very radical, 35MM cameras give you a lever that transports the exposed film out of the camera and into a storage area while a fresh segment of film is moved behind the lens ready for the next picture. That light tight compartment is equivalent to your permanent digital camera storage system.

Some Comparisons

How often have you taken a really nice conventional film picture and not be able to view it? The image remains locked in the light tight camera until the roll is finished or you sacrifice the remaining unexposed film. One of the best advantages of digital film is that the entire storage device need not be filled before you transfer any pictures to the computer. You could even put one single picture on your memory card and then change cards.

Are you on a trip and you run out of film? Someday you may be able to buy flash cards at your local tourist shops but today they are specialized and somewhat difficult to obtain. The lower end Sony cameras use floppy disks and they are readily available. Memory cards are also rather expensive as an investment but you should realize they are reusable so long as you don't damage them or lose them. When you run out of digital film you can transfer the images to a computer and then delete them from the card freeing up the space for new pictures. With many digital cameras you can edit the shots instantly in the field and eliminate some of the less desirable ones freeing up the storage space for more pictures. More sophisticated users will drag along a laptop with tiny removable hard drives that store many, many pictures. Digital camera photographers are accustomed to sitting on the top of a mountain editing their collection of pictures. It's all part of the process.

In all, there are two separate issues here. First, digital film offers you much more flexibility than chemical film. But the flexibility brings you more problems with organization and management. Editing pictures in the field is more of a hassle than working later on your computer but may be essential. Management of your newly acquired conventional film inventory required shoe boxes and a wastebasket. Besides, there was always a lag of several days between the time you exposed the picture and the earliest time you could see the images.

Instead of comparing the two photographic systems, consider each in their own uniqueness. Digital film is much closer to an ordinary scan or a clip art graphic than to photographic negatives. Include the possibilities that the technology of scanning and manipulating scans with programs like Photoshop bring into the discussion and your concept of digital film will allow you to see the many possibilities this new technology can offer. Consider the difference in price between buying more and more chemical film and storing more and more digital files. Consider the expense of storage in the field requiring memory cards and buying rolls of chemical film so that you have enough to take all the pictures you wish. Neither system is really better than the other, they are simply different.