If anyone promises you something along the lines of "photography made easy", run for your life. Photography is a demanding art form which today involves some very capable but complex technology. Nevertheless, mastering this technology is easier than perfecting one's creativity and learning the workings of human visual perception.
Creativity is the ability to see and evaluate compelling subjects, light quality and direction, composition and perspective, sharpness, color, brightness, contrast, etc.
Creativity grows by watching and listening to master photographers and painters, and from relentless experimentation.
Mastering camera gear mostly comes down to learning how to set it up to capture well exposed, sharp pictures of your chosen subject and how the camera sensor will record it (pre-visualization). Technology is the sum of the tools that allow me to go from a real-life, compelling scene to a beautiful print. It has to do its job while staying out of the way of my creativity.
Human Visual Perception
Understanding human visual perception is learning how people's eyes collect light and how the brain processes the resulting electric signals and constructs a mind "image".
When it comes to vision, people and digital sensors work quite differently. Sensors are monoscopic and linear - twice the amount of light equals twice the amount of signal -. People's eyes are stereoscopic and non linear - light sensitivity drops with increasing brightness and color sensitivity the other way around -. They explore a scene more like a video camera by jumping around from one point of interest to the next with only a 5 degree central angle of view in sharp focus but with an adaptable dynamic range much wider than any digital camera (about 20 f/stops). Everything else is peripheral vision good for seeing shapes and movement. Every time the eyes stop on a point of interest exposure and focus are quickly optimized.
The outside light reaches the retina that contains nerve cells called "photoreceptors" which convert the light energy into electrical impulses through an electro-chemical process. Through the optical nerve, the signals reach the brain where they are deconstructed into their basic components such as color, contrast, saturation, sharpness, etc. Each component is analyzed, recognized and interpreted by different areas of the brain and then a final "image" is assembled in the occipital cortex (this is not a real image, it's a collection of electrical impulses). From previous experience and knowledge, the brain adds the perception of depth - the retina image is flat but we see in 3D and can judge distances -. The blind spot where the optical nerve attaches to the retina is also artificially filled-in.
I had the chance to verify this brain behavior while sky-mountaineering at 9,000' in the Dolomites in the limited visibility of a heavy snowstorm. What looked to me to be a giant boulder 100 yards away revealed itself to be a stone the size of a fist 20 feet away. Evidently my brain learned quickly from this experience because the phenomenon did not repeat itself. The next day though with snow still falling I could not recognize the crest of a tall snow drift, skied right over it and fell six vertical feet (right on my skis).
This analysis and interpretation process is strongly influenced by many personal factors such as intelligence, education, life experience, familiarity with the subject, health, mood, etc. To make things even more complex, we witness the outside world with all our senses and a print is a limited testimonial of the entire physical and emotional experience. Worse, the brain comes to different interpretations between seeing a scene live and watching a picture of the same subject. I converted completely from film to digital in 2004 because of the post-processing power of the latter. After the capture, Photoshop allows me to render the final image as close as possible to my perception of the original scene.
Sources of Learning
I read a lot and found Michael Freedman's three books "The Photographer's Eye", "The Photographer's Mind" and "The Photographer's Vision" particularly informative and inspirational. Martin Evening's "Adobe Photoshop (CC) for Photographers" is my go-to, encyclopedic guide for the software. Scott Kelby's "The Adobe Photoshop CC Book for Digital Photographers (2017 release) offers comprehensive coverage of Camera Raw, the Photoshop module where most of the typical processing of Raw captures should be done.
I consult dpreview.com and imaging-resource.com almost daily. These sites provide timely updates on new camera gear, useful articles/videos on technique and informative (often amusing) forum discussions. dxomark.com is also useful for an evaluation of camera sensors as long as one pays attention to what they test and how.
A very exhaustive article on digital photography vs human vision is found here: