Every so often, someone asks about buying cameras. What's the best camera to buy, is the common query. Something bigger, badder, fancier, or powerful-- the asker asks-- than the point-and-shoot that they (or their wife) already has. My answer is always the same: a qualified "don't know." I have used only a couple brands of digital cameras in my day. First were Fuji FinePix, which worked well during my early digital years. Then switched to a Canon Digital Rebel XT1. Then bought a second, so I wouldn't have to keep changing between close-up and far-away lens.
The Rebel XT is a digital SLR camera, which means single-lens reflex. Basically, when you press the shutter button, the picture is taken. Just like that, and with no shutter delay (except in lower light, or with special settings). My reason for upgrading to SLR was speed. There was too much motion on the fireground for my point-and-shoot camera to adequately capture. And as evident by the photos thus taken, the results have been positive.
Have point-and-shoot cameras advance in the years, to be comparable to digital SLR cameras? Don't know. What about Nikon or other brands of digital SLR? Don't know. Lee Wilson has taken photos with Nikon digital SLR cameras for years, and the quality of his photos speak for themselves. What camera bodies does he use? He shoots with a Nikon D60, and has used both a Nikon D50 and a Nikon D70 in his past.
Will buying and using those Canon and Nikon cameras result in pictures as good as ours? Perhaps. But there's a second piece of the equipment puzzle, and that's the lens. Er, lenses, plural. Better camera bodies call for better lenses. Yours Truly upgraded from his "kit" lens-- the one that came with the camera package-- to a higher-quality one, from the Canon "L" series. The results were better pictures, notably richer colors and "faster" photography. Meaning, light travelled through them faster than the older lenses, which helped improve low-light and night photos. (Talk about a nutshell of a explanation there!)
So, you buy the same camera and the same lenses, and then you start taking great pictures, right? Maybe. Depends on your experience both (a.) using cameras and (b.) taking pictures. I personally, and even impersonally, have far more experiencing taking pictures than using cameras. Only in the last decade or so, have I started paying attention to the settings and capabilities of the cameras that I've used. And learning is still happening. Every incident that I attend is a chance to practice, refine, and practice again.
What advice can I give, for those with new digital SLR cameras? Here's what I have done, and have learned to do. Shoot in Program Shift (P) mode, which negates both auto-flash and auto-ISO. Then, start setting the ISO yourself, and popping the flash yourself. Save your pictures in RAW, instead of JPEG. Use the post-processing software included with your camera to "process" your pictures. It's like developing your own film. Digital developing.
Take pictures often. Have camera, will travel. Take lots of pictures when taking pictures. For people pictures, five to one or ten to one is a good ratio. Snap, snap, snap, snap. Just like that. Particularly if they're candid shots. People have annoying habits of blinking, moving their mouths, and doing other interesting things with their faces that don't look entirely appealing in still photos.
For flash photos, buy an external flash, and then learn how to "bounce." That's turning and swivling the flash head, so it faces a wall or a ceilling, and then "bounces" the light back on the subject. Less direct, less harsh. Also, when possible, shoot in sunlight. Overcast days are great for even lighting, but the colors won't nearly as nice as when sunlit.
Finally, share the photos. Let others see them, and react to them. Let yourself become aware that others will be seeing your photos, which can result in a nice feedback loop. It's like performance. When you realize that you're on stage-- or going to be on stage-- you take your work a little more seriously. And that's about it, I guess, for quick tips and an answer to the original quesiton.
Finally, here are a couple articles for further reading. There are many, many more. Google is your friend.
Signed, a guy who takes a lot of pictures, and still learning how to take them.
1 The Rebel XT has been superceded by subsequent models, such as the XTi and Xsi. Good site for camera information is Digital Photography Review.