If you decide to go the Digital SLR (DSLR) route you need to consider more variables than you do with a point and shoot (P&S) camera. People tend to be pretty passionate about supporting their brand choice so you need to take these conversations with a grain of salt. At the end of the day, the camera is just a tool.
The order of importance, in regard to picture quality, with a DSLR is:
Buying a DSLR is more than buying a camera, it’s buying into a system. That being said Canon and Nikon currently have most of the market. Choosing one of those gives you more choices for expansion down the road. That doesn’t mean that other brands aren’t capable of good images. Sony, Pentax, Olympus, Sigma, etc., will all produce quality images when used properly. While pixel count can be important it shouldn’t be the feature that sells the camera
Lens choices are far more important than which body you buy. Most importantly, you have to be comfortable with how the camera feels. If you’re not comfortable with your camera you won’t be out shooting with it. Go to a local camera store (avoid places like Ritz, Best Buy, etc., if at all possible), play with several different camera bodies and see what feels the best in your hand. Buy the one that feels best.
If you go to a local store with subject expertise (again, not a Ritz, Best Buy, Wolf Camera, etc) and take advantage of the knowledgeable folks buy your camera there. You might pay a little bit more but they deserve to be compensated for their assistance. In the long run building a relationship with a local store can be very helpful as a good camera is a long-term investment. I have no problem buying online to save money; I just don’t do it if I’ve involved the local store in the sales process.
Saving money, by buying used gear, allows you to spend more money on lenses. A good lens on a used body will take better pictures than a cheap lens on a brand new body. There are several websites that you can purchase used gear from and still have the ability to return the product if something isn’t right. I’ve purchased used gear from B&H Photo/Video and Adorama. Keh and Calumet are also options; I just don’t have personal experience with them.
Some sensor nomenclature
The modern DSLR is based on the 35mm film format. Many brands even share lenses with their film brethren. When discussing DSLRs you often hear phrases like “full frame”, “crop sensor” or “crop body.” What’s being referred to is the size of the imaging sensor in the camera. The later two, refer to a camera with a sensor that is smaller than a frame of 35mm film. The actual size varies between manufacturers.
Because the sensor is smaller than standard film, it records a smaller portion of the image circle projected by the lens. The result is additional magnification. Canon, for example, uses a 1.6x cropped sensor in their consumer bodies. A 100mm lens on a Canon 40D, while maintaining the depth of field and focus characteristics of a standard 100mm lens gives a magnification of the image equivalent to a 160mm lens. Many Nikon cameras use a 1.5x factor, while cameras based on the 4/3s system have a 2.0x factor.
focal length x crop factor == apparent magnification
Full-frame, very simply, means that the image sensor is the same size as a frame of 35mm film. Lenses perform just like they would on a film camera, with no additional magnification. Until recently only Canon sold DSLRs with a full frame sensor. In the last year Nikon and Sony have released their own versions. If you’re moving from a cropped camera to a full frame version make sure that you check your lenses for compatibility with the new body. Many less expensive consumer grade lenses either won’t work at all or won’t produce quality results on a full frame body.
Using Canon as an example, while their EF lenses work on the entire camera line, their EF-S line of lenses only works on the Digital Rebels and the 20,30,40 and 50D. 3rd party brands like Tamron and Sigma will frequently use the phrase “Digital only” to differentiate their lenses designed for crop body cameras.
An evil fact of life
DSLR cameras have one problem that is unavoidable; sensor dust. The imaging sensor develops a static charge while it’s capturing an image. The result is that it becomes a magnet for dust in the camera. Even if you never remove the original lens you will, eventually, end up with dust on your sensor. Wear from moving parts alone cause dust. Many newer cameras have some built-in dust management but at some point you will still have to deal with dust, as they aren’t perfect. At wide apertures (smaller number) dust generally isn’t noticeable. Many folks, shooting in automatic modes, don’t even realize that they have a problem.
To check for dust set your camera to aperture priority and dial in the smallest aperture that you can (highest number). Point the camera up at clear blue sky and click the shutter. Open up the image on your computer and take a look. Dust appears as dark, out of focus, spots on your image.
Check your camera manual for supported methods of removing the dust. The simplest just involves using a hand operated bulb blower to dislodge the dust. Most cameras have a setting to allow this. There are other cleaning methods available that involve brushes or swabs with a cleaning fluid. While I feel that used properly those methods are safe, they will void your camera warranty if you cause damage. Determining whether that’s an acceptable risk is entirely up to you.
A word of caution
There are a ton of really sleazy resellers in the camera business. The typical method of operation is this:
You see an unbelievably cheap price on the a camera on their website. You place your order online. A few minutes later you get an email telling you to call and verify your CC information. Once they get you on the phone the start selling you add-ons (that would normally come with the camera) like batteries, software, cables, etc.
If you refuse the upgrades your camera suddenly becomes back-ordered and never ships. If you agree to them you end up getting a grey market camera body (no US warranty) and a bunch of 3rd party add-ons for more money that the camera would have cost from a legitimate reseller.
If the price seems too good to be true check out the vendor at: ResellerRatings.Com.