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Introduction to
Digital Photography

So what is digital photography and how is it different from film photography? In a word, a digital image exists as a collection of "pixels" (picture elements) rather than as silver halide crystals and dye clouds. A digital image is really the same principle as mosaic pictures you have seen formed with little pieces of ceramic tile.  The little pieces of digital "tile" are just much smaller and easier to work with.

An image or photo can be "captured" or "taken" either on film or digitally. The image or photo can be printed either traditionally or digitally.  Either kind of image can be converted to the other. A digital file can be converted to film and printed traditionally. A film image can be scanned into a computer and printed digitally.

TRADITIONAL (ANALOG) PROCESSES

At the risk of oversimplification, in analog film photography, a lens focuses an image on the film. As light strikes the emulsion layer(s) of photographic film it causes a reaction that creates a "latent" image in the film. When the film is processed, the latent image becomes visible.  The result is either a negative or a slide.

The negative or slide can be used to make an analog photographic print in a similar way. A light source shines through the negative or slide and projects an image via a lens on light sensitive photographic paper. A reaction occurs in the paper forming a latent image.  When the paper is processed the image becomes visible. This image is an "enlargement" of the original slide or negative.

There are variations in the process depending on the type of film and paper, but the essential principle is the same. Latent images are formed on light sensitive film or paper.  The latent image is revealed when the film or paper is processed.

If extra light hits the film or paper before it is processed and the image fixed, the original image can be ruined.   That is why the film and paper are handled in a darkroom, or at least a dark container.

DIGITAL PROCESSES

In digital photography, the lens focuses the image on an electronic sensor (usually a CCD or CMOS sensor) that is sensitive to light. The sensor captures the image as a grid work of gray or colored pixels. The electronic image is then saved to a storage device in the camera to be transferred to a computer later. Some electronic cameras write their images directly to computer.

Unlike film which is used for only one image per frame, once the sensor in the camera has written the image to memory, it can be used again to capture another image which is also written to memory. This process can continue until all of the memory in the camera has been used up. All the images in the memory must then be transferred to computer or another storage device before the memory in the camera can be cleared and used again.

Most digital cameras have a built in viewing screen so you can look at the photos in a very small size right after you take them. Unfortunately, most of these viewing screens eat up battery life at an atrocious rate.

Once the images are in the computer, they can be looked at, changed, enhanced, and manipulated in all kinds of ways.

To create a digital print, the image is sent to a digital printer. The printer usually places tiny droplets of ink, dyes, or pigments on a piece of paper.  With a few exceptions, digital prints from home ink jet printers do not have nearly as long a "fade free" life as a print made in a traditional analog process. Some commercial digital printers and a very few home digital printers can produce digital prints that outlive analog prints.

CONVERSIONS

Negative or slide film can be scanned and converted into a digital file to be viewed and edited in a computer.  The digital image can now be printed digitally. Good quality film scanners still cost from several hundred to over a thousand dollars. For as little as $1 to $3 dollars per image, you can have film scanned and put on a CD-ROM disc for your use. One example is Kodak Photo CDs.

Analog prints can also be scanned on good quality, but inexpensive (less than $150) flatbed scanners to convert them to a digital format.

A digital image can be written back to analog film via a film recorder. Film recorders cost several thousand dollars so this is not your typical do-it-yourself project. Several labs will convert digital files to film for about $5 to $8 per image. This film can now be used to make an analog print. A digital file written to analog slide film can be used in an analog slide show.

There are some digital printers that use light emitting diodes to print digital images on long lasting analog papers.

There are all kinds of ways that images can go back and forth from analog to digital or vice versa.

ADVANTAGES AND DISADVANTAGES

COSTS & ENLARGEMENTS: Taking pictures on film is, all things considered, cheaper than digital photography when you factor in the cost of the digital cameras and the cost to print all of your own images - not to mention the time involved.

At the current state of the art, a film camera costing less than $100 can produce an image on film that enlarges to a bigger size and looks better than a digital image from a $1000 point and shoot digital camera.  Even a negative from a $10 single use camera can produce a better enlargement than an image from many 1 or 2 megapixel digital cameras costing several hundred dollars.

One nice thing about film is the wonderful continuous tonal range of the images. As you enlarge an analog image, you can see the gradual shift in tones and colors that give good images their look of quality. Eventually, an over enlarged analog image starts to look soft. If you enlarge a digital image enough, you end up seeing the pixels as little square blocks.  Unless you have a very large digital file, digital enlargements get jagged long before analog images go soft.

Digital imaging is catching up. A $3000 professional digital camera can now take images that are the equal of film enlargements in sizes up to 11x14 inches.  For enlargements beyond 11x14, 35 mm film still rules.

Digital camera prices continue to drop and quality continues to rise.

High resolutions scans from 35 mm analog slides have been blown up to huge sizes with better quality than an analog print from the same 35 mm slide -  one of the advantages of starting with analog film and converting the image to high resolution digital.

One of the disadvantages to film photography is buying film and paying to have it processed.

PROJECTION: Analog slides used in a projector still have a quality that digital projectors can not yet equal. Digital projectors are improving in quality and digital projectors make digital shows much more convenient than hauling around 2, 4, 6, or more analog slide projectors and  dissove units.

SPEED & EDITING: Taking digital photographs allows you to see the photos right away. There is no waiting for your film to be processed.  You can throw away the non-keepers. With film, you have no chance to edit as you go along.

Where speed counts, as in media photography, digital camera images can be taken and immediately sent online to a newspaper or magazine for publication.

However, speed can also be a toss up.  If you shoot five rolls of negative film and drop it off at the local one hour lab for prints, and take the same number of digital images and download them to your computer and print them out on your digital printer, the one hour lab will probably win and save you the hassle of doing it yourself (and give you an hour to do something else). If you need one image fast, digital wins.

DARKROOM: The analog darkroom is, well, dark. There are lots of chemicals which smell (some folks like the smell) and can irritate the skin. The digital darkroom uses lots of water. The nice thing about the "digital darkroom" is that you do everything in the light on a computer. No chemicals, no irritation, no fumes.

I freely confess that there is something wonderful about watching an analog black and white print appear in the developer under a safelight that is much nicer than watching a print come out of an ink jet printer.

IMAGE MANIPULATION: Digital wins hands down.  Digital images are much easier to change, enhance, correct, modify, and combine. A person with a modest amount of skill and an image processing program can do things to digital images that only a very few highly skilled (and expensive) analog retouchers can do. There are also some things that can be done digitally that would be virtually impossible to do by retouching.

In a professional studio in Albuquerque, New Mexico, I was privileged to see the work of a master retoucher.  She had two large analog prints of a horse with its head, muzzle, and body held in place by several wires tied to the horse and staked to the ground.  The image would appear in a classy equestrian publication. She used fine tipped brushes and many shades of retouching dyes to careful remove all of the wires and stakes from the photo.  She carefully mixed different shades of dyes to perfectly match every different hue and shade of leaves, blades of grass, plants, rocks, and fences in the background, not too mention matching all of the textures and colors of the horse's body.  It was a long and arduous process.  I looked at the retouched print and the original print and I couldn't detect the slightest hint of where the wires had been in the retouched print. It was amazing.

The retouched print was re-photographed on large format slide film and sent off to the publisher.

Today, she is also a master digital retoucher. She will work in whichever medium her client requests but she prefers the ease and quickness of digital retouching.

Today, most anyone could remove a stray telephone wire across the sky with the cloning tool of an image editor.

This is not to say anyone can do any kind of retouching. There are still things that only master digital retouchers can do well.  I am simply saying there are lots of things many of us can do digitally that few of us could do with analog processes.

BOTH: The good news is that you can do analog photography, digital photography or both. This site has several examples of things you (or someone else) can do to save, restore, repair, and correct your valuable photos through digital processes, while you continue to merrily click away with your analog or digital camera.

February 28, 2001

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