So what do you need to know about photography in this age?
That there is still a difference between what is sold to the consumer and what is sold to the professional. The great majority of digital cameras out there are called "Point and Shoot."
They perform the same function as did similar film cameras. True, they often have program upon program built into them that provide you with many choices and much flexibility in your picture taking, but the vast majority of people set their camera on the initial standard setting, the "P" or "green window" and never try any other option.
They do not read the instruction manual and they do not learn how to do more than accomplish playback of the images they shot. ISO setting remains a mystery and what image quality they should choose is another mystery. P&S cameras usually have small zoom lenses that use relatively small f-stop values, meaning they aren't really good for low-light shooting, but they often have anti-shake technology to compensate for the low light. They also have what is called "shutter lag," the delay between pushing the shutter button and the actual capture of the image by the camera.
Advanced amateur and professional level cameras have more options and the use of interchangeable lenses. They still use an optical viewing system, which means a shorter time lapse between seeing the image and getting the image captured by the camera. Such cameras are heavier and bigger. They can capture images that rival the best of professional film images. And the time is fast approaching when even that will be surpassed. Because of photo editing programs like Adobe's Photoshop, one need only carry one or two glass filters and a couple of light but powerful flashes. On the other hand, the pro shooter now must have a multi-capable cell phone and a laptop computer with WiFi and the means of producing quick copies of disks. Also a couple of extra hard drives, numerous memory cards and, even a small printer (to do what Polaroids used to do).
Here are your essentials: (And you've probably heard it before, elsewhere):
Read your instruction manual. ISO refers to the light recording ability of your camera. The higher the ISO, the more light sensitive it may be to allow you to shoot in lower light. But if you want images you can enlarge for nice looking prints, you want to set your camera for the lowest ISO setting that you can use without introducing camera shake. The higher the ISO, the greater the noise levels in the image. Noise is the equivalent of grain in film, in that the components of color information become visible to the eye in a large print.
I suggest you read up on aperture and shutter speed controls, because they are linked together to produce your images. Basically higher shutter speeds produce less shake, but also take in less light. The lower the f-stop number the more light passes through the lens, but the more narrow the zone that is in focus (depth of field). Programs in the camera adjust these values for you under varying conditions (but you can usually override them if you know what you are doing).
In bright light the camera chooses a faster shutter speed and a smaller aperture, consequently your images appear more in focus from near to the camera to very far away. In low light the camera set a large aperture and a slow speed to let in more light (or turns on the flash), so objects farther or nearer than the actual focal point will be out of focus (or too dark in the distance and washed out in the foreground in the use of flash).
The human body is prone to a lot of movement and pulsations that produce camera shake, so camera makers use systems to compensate for body movement, but that can only do so much. It is still a good idea to use a braced stance or hold the camera on or next to a solid object under low light conditions-or use a tripod.
All flashes are limited in their reach. The built-in flashes on P&S cameras and some Digital Single Lens Reflex (DSLR) cameras are more limited than detachable high-power flashes. When you see people at a concert popping off flashes from way back in a crowd, the images they get are from the brightness of the stage lights, not the power of their little flashes.
Nearly all cameras offer a maximum image size and a minimum. The Images can be recorded in JPEG (.jpg) TIFF (.tif) and/or RAW formats of various designations. If RAW is available to you, it will record more information than any of the other formats. The camera likely comes with a conversion program that allows you to do a basic edit of the image choosing which part of the information you want in a JPEG or TIFF file which can then be more thoroughly edited in Photoshop.
If you aren't comfortable working with RAW, stick with the basic format your camera offers. Raw also uses the maximum amount of pixel information. If you want to be able to record more images, use one of the standard formats and choose to record at a smaller size. These options are available in the cameras menu or setup controls. But, the smaller the image in pixels, the smaller the print will have to be to maintain good sharpness.
At 640X480 pixels any print over snapshot size begins to show the small squares that make up the pixels. When you reach, say, 2496X1664 pixels, you can produce a 16" by 20" (58 by 88 cm) print that shows no sign of pixelization.
What limits you in how many pictures you can record is the memory card that resides in your camera. It's surprising how many people don't know the cards are interchangeable. Or that you can carry around several cards in your pocket (protected, of course). Memory cards take the place of film in terms of image storage. But transferring image files from a card to a hard drive and copying them to a disk, does not degrade them in any way.
Manipulating the image of an individual file can degrade or change the image, but if you only work from a copy, or your editing program maintains the original file intact while creating a working copy, nothing in your original is lost. I always save the image I'm working on with a modified file name, so the original isn't inadvertently lost.
As soon as you've shot a set of images-or a day's worth-transfer them from the card to a computer hard drive or disk, then erase the card (or reformat it) in camera and you are ready to go again. I always save important files to two different locations, a hard drive and a disk, for instance.
Beyond this point we get into the esthetics of image making and the tools available in photo editing programs. I think there are other people who have much more information than I to help you improve in those areas.
I think you can see that the basic tasks of film photography have become the basic tasks of digital photography. So any old book of basic photography techniques can help you in the current age of digital. Of course, the more you learn from any source, the better you will be able to capture the great new images of the 21st century and, possibly, for the ages.