Part II – Understanding the Basics of Digital Photography

By John Anderson

Capturing images on film is no longer mainstream, and only purists continue to expose silver halides and process them in a darkroom. When I started doing serious photography in the early 1970’s, color film was still improving, and only Kodachrome yielded consistently great results, a fact that did not go unnoticed by Simon and Garfunkel. (Millenials should Google this.)

For consumer use, digital capture became available in the mid-1990’s although the images produced by the early cameras weren’t very good. Today’s cell phones surpass anything from the ’90’s and early 2000’s. Some rely entirely on their phones, and I honestly can’t disagree, but there are limitations. On safari, cell phones don’t cut it.

Photographing a female cheetah and her cubs at daybreak in the Masai Mara required a 600mm telephoto lens nestled on a sand bag to keep it steady in the low light. ©2016 John R. Anderson

Photographing a female cheetah and her cubs at daybreak in the Masai Mara required a 600mm telephoto lens nestled on a sand bag to keep it steady in the low light. ©2016 John R. Anderson

 

Instead of film, digital cameras have a sensor. If you’ve had a digital dental x-ray, that thing they put in your mouth is the sensor, and the plastic covering keeps light from exposing it. The x-rays, however, pass through the plastic and make the image. Today’s most popular sensor is the CMOS (complementary metal-oxide semiconductor), and it works by converting light into electrons. The CMOS sensor allows fast image processing and facilitates video, something that did not occur in the early years of digital photography.

Two factors affect the quality of the digital image at a fundamental level: the size of the image sensor, and the number of megapixels (1 million pixels equals a megapixel or MP) captured by the sensor. Both are building blocks that limit the potential from the digital file. For many photographers and manufacturers, maximizing the pixel count was the only priority, and that has been a slow and costly road. As an example, a 6MP DSLR (digital single lens reflex) camera cost around $25,000 in 2001. By 2003, the price had dropped nearer to $6,000.

Some professional DSLR’s have an Fx sensor, equivalent in size to a 35mm film frame, but most other cameras have smaller sensors. This is especially true of cell phones where the depth of the device is so shallow. In general, larger sensors and higher pixel counts allow for better detail, larger files and can be enlarged more for display. The image processing software in the camera also can enhance photographs significantly, and updates often lead to better low light response and higher quality overall.

 

D300.Sensor.7402

The sensor in a Nikon D300 is visible with the mirror raised. The protective glass refracts the light from a flash unit. ©2016 John R. Anderson

 

A person’s satisfaction with his camera has to be judged by the final product. If you only view images on a phone or the back of a camera, the quality is not as important as for the person who is making posters or other enlargements. The Lost Generation described in Part I of this series should be an incentive to at least make some prints. Many online vendors do this very well, and even the local pharmacies and camera shops can help.

For those who like to view their images on a computer, consider that the quality of a digital photograph is not what one sees on a screen. The best computer screens are 100 ppi (pixels per inch), and most are 72 ppi. Most digital photographs are captured at 300 ppi, so the image naturally looks great on a lower resolution device. Magazines and books are typically printed at 300 ppi, and the best fine art books are printed at 600 ppi.

I hope this short explanation of digital capture clears up questions in our readers’ minds. The bottom line with photography, like any other pursuit, is that you only become better by doing it. On Friday, we’ll talk about good digital hygiene.