Sierra Nevada Airstreams: Enjoyment of the whispering winds, the zephyrs, the airstreams of the Sierra Nevada and Great Basin areas of the United States.

Owners Guide - Touring

Thinking about a Digital Camera?

The market cycle has brought us back around to the original 'Brownie' camera in that you can buy a camera with film for about ten bucks, shoot a bunch of pictures, and then return the entire camera for processing to get your pictures (and negatives). But there are other options available, too. From the 1960's to the 1990's was the era of replaceable film cameras for the typical tourist. The low end were fixed focus and aperture point and shoot cameras and the more serious enthusiast used cameras with programmable exposure and an ability to change lenses.

Starting in the 1990's, digital and solid state technology made it possible to build an 'all electronic' camera for about the price of the film cameras the more serious tourist photographers were using. These cameras did not have the ability to change lenses but did usually come with a zoom lens, automatic focus, and automatic exposure. Instead of film to store images, electronic memory was used. Electronic or digital camera images made it very easy to transfer images to a computer for enhancing, archiving, and sharing.

Advances in electronic imaging devices and cost reductions in electronic memory have resulted in digital cameras that produce better quality images at ;better and better prices. You can now get a digital equivalent to a film camera for only two to three times the cost. The digital camera gets you the benefits instant imaging without film or processing costs.


The specification that seems to have caught on as the primary indicator of digital camera picture quality is the megapixel rating. Pixel is short for 'picture element' and closely related to the resolution or ability to discern detail. The equivalent of a pixel in digital cameras is called grain in film cameras. Most digital cameras for consumer use seem to rate at about 2 to 5 million pixels or megapixels.

To get an idea of the quality of a pixel ratings consider: A typical laptop computer screen is 800x600 pixels in size or 480 thousand pixels – half a megapixel. A good quality inkjet printer is rated at about 700 pixels per inch so a 4x6 inch print would be 2800x4200 or nearly 12 million (mega) pixels. A typical 35mm film camera is considered to have the equivalent of about 3-5 megapixels of image resolution.

Digital zoom is often found in digital cameras. This is the same as cropping a picture and then using an enlarger to print it bigger. Digital zoom means an image with lower resolution (fewer megapixels) than non-zoomed images.

Lenses and zooms

The real quality issue in a camera is its lens. It is one thing to form up a single piece of plastic for a fixed focus and small aperture lenses for a disposable camera. It is another to make a lenses that can be adjusted for focus, is compensated for color problems, allows for large apertures, and can be adjusted for close-ups or wide angle scenery. The lenses in good cameras are usually by far the most costly part of the camera. In less expensive cameras it is usually the lens that takes the major brunt of cost cutting efforts. When you get lower quality lenses you will get a bit less brightness to the picture, colors will be a bit more muddy, the image won't be quite as sharp, it will be more difficult to get usable pictures in poor light situations – a lot of little things that most people won't notice objectively unless it is pointed out to them.

When buying a camera, keep the lens compromise in mind. Watch out for cameras that have very large zoom ratios: anything more than 3:1 optical zoom is very difficult to achieve in a quality lenses.

Film Speed Equivalent

Camera film is rated by how sensitive it is to light. This rating is called film speed and numbers for this rating go from 100 or so for outdoor (less sensitive) film to 800 or more for (more light sensitive) indoor film. Higher film speeds for more sensitivity tend to be grainier because larger light sensitive grains are needed to capture more light. The film speed rating for digital cameras tends towards indoor ratings in the low hundreds although the electronics and in-camera processing can change this somewhat.

Note that it is easy to change film speed or light sensitivity in film cameras by simply using a different roll of film. It is not so easy to change digital camera film speed ratings because that is built into the camera electronics.

Color and color balance

Color is another one of those science and art mixes that can be a lifetime of study. Our eyes create color by combining stimuli received from color sensitive eye parts. Our brain automatically compensates to adjust the color of what we see to what it 'ought' to be. A white sheet in bright sunlight looks white but under fluorescent lighting it may look blue and under incandescent lights or at sundown it may be reddish – but we will still see it as white.

You can buy film whose chemical sensitivity is adjusted to compensate for color differences between 'indoor' and 'outdoor' lighting to help produce images that appear to have the proper color. Sometimes you may see an image where someone used a flash with indoor film resulting in blue tinted pictures or took a picture outside with indoor film resulting in red tinted pictures.

Digital cameras adjust color sensitivity on the fly using what is called white balance. The computer in the camera scans the image and tries to figure out what white would look like. Then it adjusts the color signals from the sensor so white will look white in the captured image. Some of the better cameras allow you to point at something white and tell the camera 'this is white' to make sure that the camera knows how it should adjust its color balance.

Image storage

With film, your image storage comes in rolls that accommodate from 12 to 36 images or you can buy film in bulk and cut to convenient lengths. Once an image is put on film, the film cannot be re-used.

Digital cameras store images in electronic memory. The two biggest problems with electronic memory is having sufficient capacity to store a reasonable number of images and making sure the images won't disappear if the battery goes dead. Storage on floppy diskettes or optical media (CD-ROM) is fading as prices go down and capacity goes up for solid state memory solutions. There are also very small hard drives similar to the main storage in your computer that can be used in cameras. Motion picture electronic video cameras often use magnetic tape for image storage.

The most common and most portable type of memory for digital cameras is called compact flash. It is about an inch and a half on a side that plugs in on one side and comes in capacities up to a gigabyte or so. Other memory types for digital cameras include secure digital, Sony's memory stick, and smart media.

Most cameras allow you to choose how to store your images. In raw form, a photograph can take up a lot of space – three or four bytes for each pixel. To save on storage space, various compression schemes are used. Some of these may degrade picture quality slightly but allow you to store ten times more pictures than you could otherwise.

Archiving pictures

You can copy pictures from your camera to a computer either by connecting them together with a cable or by having a device on the computer that can read the memory media used by the camera.

Most cameras today use USB cables to connect the camera to the computer. When connected and turned on, the camera looks just like a hard drive to the computer. The cameras often come with software to help you view and manage your picture collections and move camera pictures to the computer hard drive for archiving, viewing, editing, and printing.

Other cable connections for cameras may use Firewire, which is more common on Apple computers, or old fashioned serial which is rather slow.

Digital camera issues

The digital camera is essentially a custom designed computer. It has its own operating system and built in software to read the controls, capture the picture, store it in memory and do many other things. One result if this is that the digital camera has to boot up when it is turned on. There may also be a delay after taking a picture while the camera copies the image to the storage media. And all of the electronics eats batteries. Faster boot times, shorter times between pictures, and better battery life are where more expensive cameras can show the value for their price.

The digital cameras can also offer features not found on film cameras. Many of the modern cameras can serve as a movie camera for a few seconds. Some can record sound so you can annotate a picture by telling the camera what the picture is about. You might even be able to find a camera with a GPS built in so that every picture is encoded with the coordinates of the location where it was taken.

For those who are familiar with 35mm camera lenses, digital cameras lens descriptions can be a bit confusing. The image capturing device for most digital cameras is smaller than a 35mm film frame. This means the coverage area for a lens of a given focal length is different between the camera. A wide angle 35mm lens can provide the same image on a digital camera that a normal lens would provide on the film camera.

The automatic exposure and focus may also confuse some people as it puts a delay between pressing the shutter button and the actual picture taking. You can often press the shutter button down only partway to set the focus and exposure and then press the rest of the way to snap the picture.


See the articles in the Touring Section of the Owner's Guide for articles on making better pictures, editing pictures, sharing pictures, presentations, and making a travel journal

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