Abstract art uses a visual language of form, color and line to create a composition which may exist with a degree of independence from visual references in the world. Abstraction indicates a departure from reality in depiction of imagery in art. This departure from accurate representation can be only slight, or it can be partial, or it can be complete. Total abstraction bears no trace of any reference to anything recognizable. Abstraction is described as "dissolving image" to move away from recognizable or objective reality. Abstract Art contains minimal reference to natural objects, that is, objects in the world we perceive through our senses. The aesthetic theory underlying abstract art maintains that beauty can exist in form alone, and no other quality is needed.. It "begins with an object in reality and reduces, enlarges upon, or blurs it beyond recognition". For abstract photographers, this means they "allow the lens to focus so acutely that we see the wrinkles but do not recognize the elephant in the picture."
Often photographers use macro lens to produce abstract images. Macro photography is extreme close-up photography, usually of very small subjects, in which the size of the subject in the photograph is greater than life size. Thanks to new technology photographers today can fuse art and science. Abstract photography excites the senses in an unusual way, not really to tell a story like traditional photography but to demonstrate elements of surprise and wonder. You may not always know what you are looking at with abstract photography, but then the meaning and emotional impact is all so personal and different from one person to another. Many abstract photographers use subject matters that are real in life but photographed so you, the viewer, see it in the most unusual way. The subjects could range from people, plant life, places, animals or inanimate objects, photographed with the most unique exposure settings in the most unlikely way. Angles give an effect so magnificent in one fantastic sensation for your total experience.
The most important elements in Abstract photography are: color,form and line. I would also add Texture and Lighting. One of the most famous abstract photographers is Aaron Siskind. His work focuses on the details of nature and architecture. He presents them as flat surfaces to create a new image out of them, which, he claimed, stands independent of the original subject.
REFERENCES:  Wikipedia: http://en.wikipedia.org/wiki/Photography Anne Darling (http://www.annedarlingphotography.com/abstract-photographers.html)  "The Creative Impulse. An Introduction to the Arts" Dennis J. Sporre; 444p  http://ultramodernstyle.com/abstract-photography-in-modern-interiors