Most photographers are consciously or subconsciously attempting to reach particular areas of thought and emotion that may lay dormant within the mind of the common viewer or a special audience. Much of our brain activity is comprised of images remembered, both still and moving, real and photographic. Great photographs trigger ideas, memories, conclusions or questions. They evoke feelings. More often than not, the photographer is at least partially aware of such feelings when the image is first taken. Therefore we are astutely aware of expressional subtleties that evolve in microseconds or sunsets that change in seconds. The who, what where and when of a photograph can have a direct effect on our expectations and knowledge of the subject matter.
Light, Tonality, Texture and Color
Light is powerful. It comes in myriad forms. Some photographers worship it. The ability to manipulate natural and/or artificial light is important to good photography. Monotone photography fans disregard color in order to emphasize the complimentary qualities of tonal differences and gradients. Tone and texture multiply the character of light. Color has a dynamic all its own. Each color has a relationship to each other color. The colors in photographic images appeal to individual feelings and preferences, some evoking special emotions.
Composition: Line, Perspective, Form, and Arrangement
Filmmakers and professional photographers take pains to place the camera at proper angles to achieve image values that juxtapose ideal lines, shapes, arrangements and perspectives. Most good photographers can see these interplays of line immediately yet will often study them at length for hours or even weeks beforehand to improve upon them. Head-to-toe portrature, film noire, Indy races, model and architectural photography rely heavily on awareness of line even where it is invisible or subconscious to the end viewer. I studied perspective as an artist in my teens. This has improved my awareness of it in my own photography.
Without preparing a subject, a set, an environment or a location, most images contain incongruous distractions that should have been removed. For instance a model or subject may have hair problems, a background may contain distracting objects, a glamorous home exterior may have litter that might escape preliminary notice. A wedding shot might reveal someone's blurred presence crossing in the background. To achieve clean images a photographer will usually look for these problems in advance and remedy them before shooting. They are difficult or impossible to remedy in film output. But they are sometimes easy to remedy in digital images.
Framing and Cropping
The four walls of a photo are important given that most images are rectangular. The edges of an image may contain valuable portions of content or the main part of subject or subject matter may be near an edge. But more importantly, the edges of an image define what the inner portion shows. Many photographers rely on the "rule of thirds", which places a center of visual attention one third from the edge. Most photographers probably feel compelled to frame at least ten percent wider than target area in order to allow for cropping and margin of error. Cropping itself is a fine art.
Variety and Variation
Every photographer wants every shot to count. But even the greatest photographers shoot far more pictures than they expect to use. Most professional photo assignments end with a large percentage of images never being printed. Often times a client will love the discards as much as the better images. More often than not, there are good and bad surprises in the end product. Therefore it is a standard rule that most serious photographers will shoot a number of variations for a particular subject or scene even if no significant change appears visible to the amateur. Variations in posture and facial expression occur at a rate of many times per second. Fashion photographers may typically snap scores of images in a mere span of five minutes. Today's digital imaging makes it affordable to shoot images in larger quantity and thus get more ideal results.
Particular human subjects, animals, or subject matter have innate photographic value. It is often surprising when attractive people lack such talent or when otherwise unattractive people look like glamorous superstars on film. The photographer can manipulate any number of things including light to achieve particular results. But many subjects, even shy ones, are surprisingly excellent models. Often times photogenic value is not fully realized until the pictures are viewable. Human subjects in particular offer a wide diversity of natural abilities, talents and character . These subtle elements come out in smiles, body language, manner of expression and in fashion and grooming.
Technical Skill and Tools
Today's professional and "pro-sumer" cameras present a daunting number of options. Therefore each photographer tends to have a personal relationship with his tools. Technical skill is the ability to master camera settings, control flash and manipulate the final results in a lab or digitally. Today's cameras can also be very forgiving by allowing degrees of automatic control. But even so, some technical skill is required to maximize results.